Coverage Report

Coverage Report - net.wotonomy.web.URI

Classes in this File
2.893
 /*
  * $Header$
  * $Revision: 905 $
  * $Date: 2006-02-19 01:44:03 +0000 (Sun, 19 Feb 2006) $
  *
  * ====================================================================
  *
  * The Apache Software License, Version 1.1
  *
  * Copyright (c) 2002 the Apache Software Foundation.  All rights 
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer. 
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution, if
  *    any, must include the following acknowlegement:  
  *       "This product includes software developed by the 
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowlegement may appear in the software itself,
  *    if and wherever such third-party acknowlegements normally appear.
  *
  * 4. The names "The Jakarta Project", "HttpClient", and "Apache Software
  *    Foundation" must not be used to endorse or promote products derived
  *    from this software without prior written permission. For written 
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache"
  *    nor may "Apache" appear in their names without prior written
  *    permission of the Apache Group.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  *
  * [Additional notices, if required by prior licensing conditions]
  *
  */ 
 
 // excellent class borrowed from Apache Commons project:
 //package org.apache.commons.httpclient;
 
 package net.wotonomy.web;
 
 import java.io.IOException;
 import java.io.Serializable;
 import java.io.UnsupportedEncodingException;
 import java.net.URL;
 import java.security.AccessController;
 import java.util.BitSet;
 import java.util.Hashtable;
 import java.util.Locale;
 
 import sun.security.action.GetPropertyAction;
 
 /**
  * The interface for the URI(Uniform Resource Identifiers) version of RFC 2396.
  * This class has the purpose of supportting of parsing a URI reference to
  * extend any specific protocols, the character encoding of the protocol to 
  * be transported and the charset of the document.
  * <p>
  * A URI is always in an "escaped" form, since escaping or unescaping a
  * completed URI might change its semantics.  
  * <p>
  * Implementers should be careful not to escape or unescape the same string
  * more than once, since unescaping an already unescaped string might lead to
  * misinterpreting a percent data character as another escaped character,
  * or vice versa in the case of escaping an already escaped string.
  * <p>
  * In order to avoid these problems, data types used as follows:
  * <p><blockquote><pre>
  *   URI character sequence: char
  *   octet sequence: byte
  *   original character sequence: String
  * </pre></blockquote><p>
  *
  * So, a URI is a sequence of characters as an array of a char type, which
  * is not always represented as a sequence of octets as an array of byte.
  * <p>
  * 
  * URI Syntactic Components
  * <p><blockquote><pre>
  * - In general, written as follows:
  *   Absolute URI = &lt;scheme&gt:&lt;scheme-specific-part&gt;
  *   Generic URI = &lt;scheme&gt;://&lt;authority&gt;&lt;path&gt;?&lt;query&gt;
  *
  * - Syntax
  *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
  *   hier_part     = ( net_path | abs_path ) [ "?" query ]
  *   net_path      = "//" authority [ abs_path ]
  *   abs_path      = "/"  path_segments
  * </pre></blockquote><p>
  *
  * The following examples illustrate URI that are in common use.
  * <pre>
  * ftp://ftp.is.co.za/rfc/rfc1808.txt
  *    -- ftp scheme for File Transfer Protocol services
  * gopher://spinaltap.micro.umn.edu/00/Weather/California/Los%20Angeles
  *    -- gopher scheme for Gopher and Gopher+ Protocol services
  * http://www.math.uio.no/faq/compression-faq/part1.html
  *    -- http scheme for Hypertext Transfer Protocol services
  * mailto:mduerst@ifi.unizh.ch
  *    -- mailto scheme for electronic mail addresses
  * news:comp.infosystems.www.servers.unix
  *    -- news scheme for USENET news groups and articles
  * telnet://melvyl.ucop.edu/
  *    -- telnet scheme for interactive services via the TELNET Protocol
  * </pre>
  * Please, notice that there are many modifications from URL(RFC 1738) and
  * relative URL(RFC 1808).
  * <p>
  * <b>The expressions for a URI</b>
  * <p><pre>
  * For escaped URI forms
  *  - URI(char[]) // constructor
  *  - char[] getRawXxx() // method
  *  - String getEscapedXxx() // method
  *  - String toString() // method
  * <p>
  * For unescaped URI forms
  *  - URI(String) // constructor
  *  - String getXXX() // method
  * </pre><p>
  *
  * @author <a href="mailto:jericho@apache.org">Sung-Gu</a>
  * @version $Revision: 905 $ $Date: 2002/03/14 15:14:01 
  */
 class URI implements Cloneable, Comparable, Serializable {
 
 
     // ----------------------------------------------------------- Constructors
 
     protected URI() {
     }
 
     /**
      * Construct a URI as an escaped form of a character array.
      * An URI can be placed within double-quotes or angle brackets like 
      * "http://test.com/" and &lt;http://test.com/&gt;
      * 
      * @param escaped the URI character sequence
      * @exception IOException
      * @throws NullPointerException if <code>escaped</code> is <code>null</code>
      */
     public URI(char[] escaped) throws IOException {
         parseUriReference(new String(escaped), true);
     }
 
 
     /**
      * Construct a URI from the given string.
      * <p><blockquote><pre>
      *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
      * </pre></blockquote><p>
      * An URI can be placed within double-quotes or angle brackets like 
      * "http://test.com/" and &lt;http://test.com/&gt;
      *
      * @param original the string to be represented to URI character sequence
      * It is one of absoluteURI and relativeURI.
      * @exception IOException
      */
     public URI(String original) throws IOException {
         parseUriReference(original, false);
     }
 
     /**
      * Construct a URI from a URL.
      *
      * @param url a valid URL.
      * @throws IOException
      * @since 2.0 
      */
     public URI(URL url) throws IOException {
         this(url.toString());
     }
 
 
     /**
      * Construct a general URI from the given components.
      * <p><blockquote><pre>
      *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
      *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
      *   opaque_part   = uric_no_slash *uric
      * </pre></blockquote><p>
      * It's for absolute URI = &lt;scheme&gt;:&lt;scheme-specific-part&gt;#
      * &lt;fragment&gt;.
      *
      * @param scheme the scheme string
      * @param scheme_specific_part scheme_specific_part
      * @param fragment the fragment string
      * @exception IOException
      */
     public URI(String scheme, String scheme_specific_part, String fragment)
         throws IOException {
 
         // validate and contruct the URI character sequence
         if (scheme == null) {
            throw new IOException(/*IOException.PARSING,*/ "URI: scheme required");
         }
         char[] s = scheme.toLowerCase().toCharArray();
         if (validate(s, URI.scheme)) {
             _scheme = s; // is_absoluteURI
         } else {
             throw new IOException(/*IOException.PARSING,*/ "URI: incorrect scheme");
         }
         _opaque = encode(scheme_specific_part, allowed_opaque_part);
         // Set flag
         _is_opaque_part = true;
         setUriReference();
     }
 
 
     /**
      * Construct a general URI from the given components.
      * <p><blockquote><pre>
      *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
      *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
      *   relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
      *   hier_part     = ( net_path | abs_path ) [ "?" query ]
      * </pre></blockquote><p>
      * It's for absolute URI = &lt;scheme&gt;:&lt;path&gt;?&lt;query&gt;#&lt;
      * fragment&gt; and relative URI = &lt;path&gt;?&lt;query&gt;#&lt;fragment
      * &gt;.
      *
      * @param scheme the scheme string
      * @param authority the authority string
      * @param path the path string
      * @param query the query string
      * @param fragment the fragment string
      * @exception IOException
      */
     public URI(String scheme, String authority, String path, String query,
                String fragment) throws IOException {
 
         // validate and contruct the URI character sequence
         StringBuffer buff = new StringBuffer();
         if (scheme != null) {
             buff.append(scheme);
             buff.append(':');
         }
         if (authority != null) {
             buff.append("//");
             buff.append(authority);
         }
         if (path != null) {  // accept empty path
             if ((scheme != null || authority != null)
                     && !path.startsWith("/")) {
                 throw new IOException(/*IOException.PARSING*,*/
                         "URI: abs_path requested");
             }
             buff.append(path);
         }
         if (query != null) {
             buff.append('?');
             buff.append(query);
         }
         if (fragment != null) {
             buff.append('#');
             buff.append(fragment);
         }
         parseUriReference(buff.toString(), false);
     }
 
 
     /**
      * Construct a general URI from the given components.
      *
      * @param scheme the scheme string
      * @param userinfo the userinfo string
      * @param host the host string
      * @param port the port number
      * @exception IOException
      */
     public URI(String scheme, String userinfo, String host, int port)
         throws IOException {
 
         this(scheme, userinfo, host, port, null, null, null);
     }
 
 
     /**
      * Construct a general URI from the given components.
      *
      * @param scheme the scheme string
      * @param userinfo the userinfo string
      * @param host the host string
      * @param port the port number
      * @param path the path string
      * @exception IOException
      */
     public URI(String scheme, String userinfo, String host, int port,
             String path) throws IOException {
 
         this(scheme, userinfo, host, port, path, null, null);
     }
 
 
     /**
      * Construct a general URI from the given components.
      *
      * @param scheme the scheme string
      * @param userinfo the userinfo string
      * @param host the host string
      * @param port the port number
      * @param path the path string
      * @param query the query string
      * @exception IOException
      */
     public URI(String scheme, String userinfo, String host, int port,
             String path, String query) throws IOException {
 
         this(scheme, userinfo, host, port, path, query, null);
     }
 
 
     /**
      * Construct a general URI from the given components.
      *
      * @param scheme the scheme string
      * @param userinfo the userinfo string
      * @param host the host string
      * @param port the port number
      * @param path the path string
      * @param query the query string
      * @param fragment the fragment string
      * @exception IOException
      */
     public URI(String scheme, String userinfo, String host, int port,
             String path, String query, String fragment) throws IOException {
 
         this(scheme, (host == null) ? null :
                 ((userinfo != null) ? userinfo + '@' : "") + host +
                 ((port != -1) ? ":" + port : ""), path, query, fragment);
     }
 
 
     /**
      * Construct a general URI from the given components.
      *
      * @param scheme the scheme string
      * @param host the host string
      * @param path the path string
      * @param fragment the fragment string
      * @exception IOException
      */
     public URI(String scheme, String host, String path, String fragment)
         throws IOException {
 
         this(scheme, host, path, null, fragment);
     }
 
 
     /**
      * Construct a general URI with the given relative URI string.
      *
      * @param base the base URI
      * @param relative the relative URI string
      * @exception IOException
      */
     public URI(URI base, String relative) throws IOException {
         this(base, new URI(relative));
     }
 
 
     /**
      * Construct a general URI with the given relative URI.
      * <p><blockquote><pre>
      *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
      *   relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
      * </pre></blockquote><p>
      * Resolving Relative References to Absolute Form.
      *
      * <strong>Examples of Resolving Relative URI References</strong>
      *
      * Within an object with a well-defined base URI of
      * <p><blockquote><pre>
      *   http://a/b/c/d;p?q
      * </pre></blockquote><p>
      * the relative URI would be resolved as follows:
      *
      * Normal Examples
      *
      * <p><blockquote><pre>
      *   g:h           =  g:h
      *   g             =  http://a/b/c/g
      *   ./g           =  http://a/b/c/g
      *   g/            =  http://a/b/c/g/
      *   /g            =  http://a/g
      *   //g           =  http://g
      *   ?y            =  http://a/b/c/?y
      *   g?y           =  http://a/b/c/g?y
      *   #s            =  (current document)#s
      *   g#s           =  http://a/b/c/g#s
      *   g?y#s         =  http://a/b/c/g?y#s
      *   ;x            =  http://a/b/c/;x
      *   g;x           =  http://a/b/c/g;x
      *   g;x?y#s       =  http://a/b/c/g;x?y#s
      *   .             =  http://a/b/c/
      *   ./            =  http://a/b/c/
      *   ..            =  http://a/b/
      *   ../           =  http://a/b/
      *   ../g          =  http://a/b/g
      *   ../..         =  http://a/
      *   ../../        =  http://a/ 
      *   ../../g       =  http://a/g
      * </pre></blockquote><p>
      *
      * Some URI schemes do not allow a hierarchical syntax matching the
      * <hier_part> syntax, and thus cannot use relative references.
      *
      * @param base the base URI
      * @param relative the relative URI
      * @exception IOException
      */
     public URI(URI base, URI relative) throws IOException {
 
         if (base._scheme == null) {
             throw new IOException(/* IOException.PARSING,*/ "URI: base URI required");
         }
         if (base._scheme != null) {
             this._scheme = base._scheme;
             this._authority = base._authority;
         }
         if (base._is_opaque_part || relative._is_opaque_part) {
             this._scheme = base._scheme;
             this._is_opaque_part = relative._is_opaque_part;
             this._opaque = relative._opaque;
             this._fragment = relative._fragment;
             this.setUriReference();
             return;
         }
         if (relative._scheme != null) {
             this._scheme = relative._scheme;
             this._is_net_path = relative._is_net_path;
             this._authority = relative._authority;
             if (relative._is_server) {
                 this._userinfo = relative._userinfo;
                 this._host = relative._host;
                 this._port = relative._port;
             } else if (relative._is_reg_name) {
                 this._is_reg_name = relative._is_reg_name;
             }
             this._is_abs_path = relative._is_abs_path;
             this._is_rel_path = relative._is_rel_path;
             this._path = relative._path;
         } else if (base._authority != null && relative._scheme == null) {
             this._is_net_path = base._is_net_path;
             this._authority = base._authority;
             if (base._is_server) {
                 this._userinfo = base._userinfo;
                 this._host = base._host;
                 this._port = base._port;
             } else if (base._is_reg_name) {
                 this._is_reg_name = base._is_reg_name;
             }
         }
         if (relative._authority != null) {
             this._is_net_path = relative._is_net_path;
             this._authority = relative._authority;
             if (relative._is_server) {
                 this._is_server = relative._is_server;
                 this._userinfo = relative._userinfo;
                 this._host = relative._host;
                 this._port = relative._port;
             } else if (relative._is_reg_name) {
                 this._is_reg_name = relative._is_reg_name;
             }
             this._is_abs_path = relative._is_abs_path;
             this._is_rel_path = relative._is_rel_path;
             this._path = relative._path;
         }
         // resolve the path
         if (relative._scheme == null && relative._authority == null || 
                 equals(base._scheme, relative._scheme)) {
             this._path = resolvePath(base._path, relative._path);
         }
         // base._query removed
         if (relative._query != null) {
             this._query = relative._query;
         }
         // base._fragment removed
         if (relative._fragment != null) {
             this._fragment = relative._fragment;
         }
         this.setUriReference();
     }
 
     // --------------------------------------------------- Instance Variables
 
     static final long serialVersionUID = 604752400577948726L;
 
 
     /**
      * This Uniform Resource Identifier (URI).
      * The URI is always in an "escaped" form, since escaping or unescaping
      * a completed URI might change its semantics.  
      */
     protected char[] _uri = null;
 
 
     /**
      * The default charset of the protocol.  RFC 2277, 2396
      */
     protected static String _protocolCharset = "UTF-8";
 
 
     /**
      * The default charset of the document.  RFC 2277, 2396
      * The platform's charset is used for the document by default.
      */
     protected static String _documentCharset = null;
     // Static initializer for _documentCharset
     static {
         Locale locale = Locale.getDefault();
         if (locale != null) {
             // in order to support backward compatiblity
             _documentCharset = LocaleToCharsetMap.getCharset(locale);
         } else {
             _documentCharset = (String)AccessController.doPrivileged(
                     new GetPropertyAction("file.encoding"));
         }
     }
 
     /**
      * The scheme.
      */
     protected char[] _scheme = null;
 
 
     /**
      * The opaque.
      */
     protected char[] _opaque = null;
 
 
     /**
      * The authority.
      */
     protected char[] _authority = null;
 
 
     /**
      * The userinfo.
      */
     protected char[] _userinfo = null;
 
 
     /**
      * The host.
      */
     protected char[] _host = null;
 
 
     /**
      * The port.
      */
     protected int _port = -1;
 
 
     /**
      * The path.
      */
     protected char[] _path = null;
 
 
     /**
      * The query.
      */
     protected char[] _query = null;
 
 
     /**
      * The fragment.
      */
     protected char[] _fragment = null;
 
 
     /**
      * The root path.
      */
     protected static char[] rootPath = { '/' };
 
     // ---------------------- Generous characters for each component validation
 
     /**
      * The percent "%" character always has the reserved purpose of being the
      * escape indicator, it must be escaped as "%25" in order to be used as
      * data within a URI.
      */
     protected static final BitSet percent = new BitSet(256);
     // Static initializer for percent
     static {
         percent.set('%');
     }
 
 
     /**
      * BitSet for digit.
      * <p><blockquote><pre>
      * digit    = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
      *            "8" | "9"
      * </pre></blockquote><p>
      */
     protected static final BitSet digit = new BitSet(256);
     // Static initializer for digit
     static {
         for(int i = '0'; i <= '9'; i++) {
             digit.set(i);
         }
     }
 
 
     /**
      * BitSet for alpha.
      * <p><blockquote><pre>
      * alpha         = lowalpha | upalpha
      * </pre></blockquote><p>
      */
     protected static final BitSet alpha = new BitSet(256);
     // Static initializer for alpha
     static {
         for (int i = 'a'; i <= 'z'; i++) {
             alpha.set(i);
         }
         for (int i = 'A'; i <= 'Z'; i++) {
             alpha.set(i);
         }
     }
 
 
     /**
      * BitSet for alphanum (join of alpha &amp; digit).
      * <p><blockquote><pre>
      *  alphanum      = alpha | digit
      * </pre></blockquote><p>
      */
     protected static final BitSet alphanum = new BitSet(256);
     // Static initializer for alphanum
     static {
         alphanum.or(alpha);
         alphanum.or(digit);
     }
 
 
     /**
      * BitSet for hex.
      * <p><blockquote><pre>
      * hex           = digit | "A" | "B" | "C" | "D" | "E" | "F" |
      *                         "a" | "b" | "c" | "d" | "e" | "f"
      * </pre></blockquote><p>
      */
     protected static final BitSet hex = new BitSet(256);
     // Static initializer for hex
     static {
         hex.or(digit);
         for(int i = 'a'; i <= 'f'; i++) {
             hex.set(i);
         }
         for(int i = 'A'; i <= 'F'; i++) {
             hex.set(i);
         }
     }
 
 
     /**
      * BitSet for escaped.
      * <p><blockquote><pre>
      * escaped       = "%" hex hex
      * </pre></blockquote><p>
      */
     protected static final BitSet escaped = new BitSet(256);
     // Static initializer for escaped
     static {
         escaped.or(percent);
         escaped.or(hex);
     }
 
 
     /**
      * BitSet for mark.
      * <p><blockquote><pre>
      * mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" |
      *                 "(" | ")"
      * </pre></blockquote><p>
      */
     protected static final BitSet mark = new BitSet(256);
     // Static initializer for mark
     static {
         mark.set('-');
         mark.set('_');
         mark.set('.');
         mark.set('!');
         mark.set('~');
         mark.set('*');
         mark.set('\'');
         mark.set('(');
         mark.set(')');
     }
 
 
     /**
      * Data characters that are allowed in a URI but do not have a reserved
      * purpose are called unreserved.
      * <p><blockquote><pre>
      * unreserved    = alphanum | mark
      * </pre></blockquote><p>
      */
     protected static final BitSet unreserved = new BitSet(256);
     // Static initializer for unreserved
     static {
         unreserved.or(alphanum);
         unreserved.or(mark);
     }
 
 
     /**
      * BitSet for reserved.
      * <p><blockquote><pre>
      * reserved      = ";" | "/" | "?" | ":" | "@" | "&amp;" | "=" | "+" |
      *                 "$" | ","
      * </pre></blockquote><p>
      */
     protected static final BitSet reserved = new BitSet(256);
     // Static initializer for reserved
     static {
         reserved.set(';');
         reserved.set('/');
         reserved.set('?');
         reserved.set(':');
         reserved.set('@');
         reserved.set('&');
         reserved.set('=');
         reserved.set('+');
         reserved.set('$');
         reserved.set(',');
     }
 
 
     /**
      * BitSet for uric.
      * <p><blockquote><pre>
      * uric          = reserved | unreserved | escaped
      * </pre></blockquote><p>
      */
     protected static final BitSet uric = new BitSet(256);
     // Static initializer for uric
     static {
         uric.or(reserved);
         uric.or(unreserved);
         uric.or(escaped);
     }
 
 
     /**
      * BitSet for fragment (alias for uric).
      * <p><blockquote><pre>
      * fragment      = *uric
      * </pre></blockquote><p>
      */
     protected static final BitSet fragment = uric;
 
 
     /**
      * BitSet for query (alias for uric).
      * <p><blockquote><pre>
      * query         = *uric
      * </pre></blockquote><p>
      */
     protected static final BitSet query = uric;
 
 
     /**
      * BitSet for pchar.
      * <p><blockquote><pre>
      * pchar         = unreserved | escaped |
      *                 ":" | "@" | "&amp;" | "=" | "+" | "$" | ","
      * </pre></blockquote><p>
      */
     protected static final BitSet pchar = new BitSet(256);
     // Static initializer for pchar
     static {
         pchar.or(unreserved);
         pchar.or(escaped);
         pchar.set(':');
         pchar.set('@');
         pchar.set('&');
         pchar.set('=');
         pchar.set('+');
         pchar.set('$');
         pchar.set(',');
     }
 
 
     /**
      * BitSet for param (alias for pchar).
      * <p><blockquote><pre>
      * param         = *pchar
      * </pre></blockquote><p>
      */
     protected static final BitSet param = pchar;
 
 
     /**
      * BitSet for segment.
      * <p><blockquote><pre>
      * segment       = *pchar *( ";" param )
      * </pre></blockquote><p>
      */
     protected static final BitSet segment = new BitSet(256);
     // Static initializer for segment
     static {
         segment.or(pchar);
         segment.set(';');
         segment.or(param);
     }
 
 
     /**
      * BitSet for path segments.
      * <p><blockquote><pre>
      * path_segments = segment *( "/" segment )
      * </pre></blockquote><p>
      */
     protected static final BitSet path_segments = new BitSet(256);
     // Static initializer for path_segments
     static {
         path_segments.set('/');
         path_segments.or(segment);
     }
 
 
     /**
      * URI absolute path.
      * <p><blockquote><pre>
      * abs_path      = "/"  path_segments
      * </pre><blockquote><p>
      */
     protected static final BitSet abs_path = new BitSet(256);
     // Static initializer for abs_path
     static {
         abs_path.set('/');
         abs_path.or(path_segments);
     }
 
 
     /**
      * URI bitset for encoding typical non-slash characters.
      * <p><blockquote><pre>
      * uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |
      *                 "&amp;" | "=" | "+" | "$" | ","
      * </pre></blockquote><p>
      */
     protected static final BitSet uric_no_slash = new BitSet(256);
     // Static initializer for uric_no_slash
     static {
         uric_no_slash.or(unreserved);
         uric_no_slash.or(escaped);
         uric_no_slash.set(';');
         uric_no_slash.set('?');
         uric_no_slash.set(';');
         uric_no_slash.set('@');
         uric_no_slash.set('&');
         uric_no_slash.set('=');
         uric_no_slash.set('+');
         uric_no_slash.set('$');
         uric_no_slash.set(',');
     }
     
 
     /**
      * URI bitset that combines uric_no_slash and uric.
      * <p><blockquote><pre>
      * opaque_part   = uric_no_slash *uric
      * </pre></blockquote><p>
      */
     protected static final BitSet opaque_part = new BitSet(256);
     // Static initializer for opaque_part
     static {
         opaque_part.or(uric_no_slash);
         opaque_part.or(uric);
     }
     
 
     /**
      * URI bitset that combines absolute path and opaque part.
      * <p><blockquote><pre>
      * path          = [ abs_path | opaque_part ]
      * </pre></blockquote><p>
      */
     protected static final BitSet path = new BitSet(256);
     // Static initializer for path
     static {
         path.or(abs_path);
         path.or(opaque_part);
     }
 
 
     /**
      * Port, a logical alias for digit.
      */
     protected static final BitSet port = digit;
 
 
     /**
      * Bitset that combines digit and dot fo IPv$address.
      * <p><blockquote><pre>
      * IPv4address   = 1*digit "." 1*digit "." 1*digit "." 1*digit
      * </pre></blockquote><p>
      */
     protected static final BitSet IPv4address = new BitSet(256);
     // Static initializer for IPv4address
     static {
         IPv4address.or(digit);
         IPv4address.set('.');
     }
 
 
     /**
      * RFC 2373.
      * <p><blockquote><pre>
      * IPv6address = hexpart [ ":" IPv4address ]
      * </pre></blockquote><p>
      */
     protected static final BitSet IPv6address = new BitSet(256);
     // Static initializer for IPv6address reference
     static {
         IPv6address.or(hex); // hexpart
         IPv6address.set(':');
         IPv6address.or(IPv4address);
     }
 
 
     /**
      * RFC 2732, 2373.
      * <p><blockquote><pre>
      * IPv6reference   = "[" IPv6address "]"
      * </pre></blockquote><p>
      */
     protected static final BitSet IPv6reference = new BitSet(256);
     // Static initializer for IPv6reference
     static {
         IPv6reference.set('[');
         IPv6reference.or(IPv6address);
         IPv6reference.set(']');
     }
 
 
     /**
      * BitSet for toplabel.
      * <p><blockquote><pre>
      * toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
      * </pre></blockquote><p>
      */
     protected static final BitSet toplabel = new BitSet(256);
     // Static initializer for toplabel
     static {
         toplabel.or(alphanum);
         toplabel.set('-');
     }
 
 
     /**
      * BitSet for domainlabel.
      * <p><blockquote><pre>
      * domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
      * </pre></blockquote><p>
      */
     protected static final BitSet domainlabel = toplabel;
 
 
     /**
      * BitSet for hostname.
      * <p><blockquote><pre>
      * hostname      = *( domainlabel "." ) toplabel [ "." ]
      * </pre></blockquote><p>
      */
     protected static final BitSet hostname = new BitSet(256);
     // Static initializer for hostname
     static {
         hostname.or(toplabel);
         // hostname.or(domainlabel);
         hostname.set('.');
     }
 
 
     /**
      * BitSet for host.
      * <p><blockquote><pre>
      * host          = hostname | IPv4address | IPv6reference
      * </pre></blockquote><p>
      */
     protected static final BitSet host = new BitSet(256);
     // Static initializer for host
     static {
         host.or(hostname);
         // host.or(IPv4address);
         host.or(IPv6reference); // IPv4address
     }
 
 
     /**
      * BitSet for hostport.
      * <p><blockquote><pre>
      * hostport      = host [ ":" port ]
      * </pre></blockquote><p>
      */
     protected static final BitSet hostport = new BitSet(256);
     // Static initializer for hostport
     static {
         hostport.or(host);
         hostport.set(':');
         hostport.or(port);
     }
 
 
     /**
      * Bitset for userinfo.
      * <p><blockquote><pre>
      * userinfo      = *( unreserved | escaped |
      *                    ";" | ":" | "&amp;" | "=" | "+" | "$" | "," )
      * </pre></blockquote><p>
      */
     protected static final BitSet userinfo = new BitSet(256);
     // Static initializer for userinfo
     static {
         userinfo.or(unreserved);
         userinfo.or(escaped);
         userinfo.set(';');
         userinfo.set(':');
         userinfo.set('&');
         userinfo.set('=');
         userinfo.set('+');
         userinfo.set('$');
         userinfo.set(',');
     }
 
 
     /**
      * BitSet for within the userinfo component like user and password.
      */
     public static final BitSet within_userinfo = new BitSet(256);
     // Static initializer for within_userinfo
     static {
         within_userinfo.or(userinfo);
         within_userinfo.clear(';'); // reserved within authority
         within_userinfo.clear(':');
         within_userinfo.clear('@');
         within_userinfo.clear('?');
         within_userinfo.clear('/');
     }
 
 
     /**
      * Bitset for server.
      * <p><blockquote><pre>
      * server        = [ [ userinfo "@" ] hostport ]
      * </pre></blockquote><p>
      */
     protected static final BitSet server = new BitSet(256);
     // Static initializer for server
     static {
         server.or(userinfo);
         server.set('@');
         server.or(hostport);
     }
 
 
     /**
      * BitSet for reg_name.
      * <p><blockquote><pre>
      * reg_name      = 1*( unreserved | escaped | "$" | "," |
      *                     ";" | ":" | "@" | "&amp;" | "=" | "+" )
      * </pre></blockquote><p>
      */
     protected static final BitSet reg_name = new BitSet(256);
     // Static initializer for reg_name
     static {
         reg_name.or(unreserved);
         reg_name.or(escaped);
         reg_name.set('$');
         reg_name.set(',');
         reg_name.set(';');
         reg_name.set(':');
         reg_name.set('@');
         reg_name.set('&');
         reg_name.set('=');
         reg_name.set('+');
     }
 
 
     /**
      * BitSet for authority.
      * <p><blockquote><pre>
      * authority     = server | reg_name
      * </pre></blockquote><p>
      */
     protected static final BitSet authority = new BitSet(256);
     // Static initializer for authority
     static {
         authority.or(server);
         authority.or(reg_name);
     }
 
 
     /**
      * BitSet for scheme.
      * <p><blockquote><pre>
      * scheme        = alpha *( alpha | digit | "+" | "-" | "." )
      * </pre></blockquote><p>
      */
     protected static final BitSet scheme = new BitSet(256);
     // Static initializer for scheme
     static {
         scheme.or(alpha);
         scheme.or(digit);
         scheme.set('+');
         scheme.set('-');
         scheme.set('.');
     }
 
 
     /**
      * BitSet for rel_segment.
      * <p><blockquote><pre>
      * rel_segment   = 1*( unreserved | escaped |
      *                     ";" | "@" | "&amp;" | "=" | "+" | "$" | "," )
      * </pre></blockquote><p>
      */
     protected static final BitSet rel_segment = new BitSet(256);
     // Static initializer for rel_segment
     static {
         rel_segment.or(unreserved);
         rel_segment.or(escaped);
         rel_segment.set(';');
         rel_segment.set('@');
         rel_segment.set('&');
         rel_segment.set('=');
         rel_segment.set('+');
         rel_segment.set('$');
         rel_segment.set(',');
     }
 
 
     /**
      * BitSet for rel_path.
      * <p><blockquote><pre>
      * rel_path      = rel_segment [ abs_path ]
      * </pre></blockquote><p>
      */
     protected static final BitSet rel_path = new BitSet(256);
     // Static initializer for rel_path
     static {
         rel_path.or(rel_segment);
         rel_path.or(abs_path);
     }
 
 
     /**
      * BitSet for net_path.
      * <p><blockquote><pre>
      * net_path      = "//" authority [ abs_path ]
      * </pre></blockquote><p>
      */
     protected static final BitSet net_path = new BitSet(256);
     // Static initializer for net_path
     static {
         net_path.set('/');
         net_path.or(authority);
         net_path.or(abs_path);
     }
     
 
     /**
      * BitSet for hier_part.
      * <p><blockquote><pre>
      * hier_part     = ( net_path | abs_path ) [ "?" query ]
      * </pre></blockquote><p>
      */
     protected static final BitSet hier_part = new BitSet(256);
     // Static initializer for hier_part
     static {
         hier_part.or(net_path);
         hier_part.or(abs_path);
         // hier_part.set('?'); aleady included
         hier_part.or(query);
     }
 
 
     /**
      * BitSet for relativeURI.
      * <p><blockquote><pre>
      * relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
      * </pre></blockquote><p>
      */
     protected static final BitSet relativeURI = new BitSet(256);
     // Static initializer for relativeURI
     static {
         relativeURI.or(net_path);
         relativeURI.or(abs_path);
         relativeURI.or(rel_path);
         // relativeURI.set('?'); aleady included
         relativeURI.or(query);
     }
 
 
     /**
      * BitSet for absoluteURI.
      * <p><blockquote><pre>
      * absoluteURI   = scheme ":" ( hier_part | opaque_part )
      * </pre></blockquote><p>
      */
     protected static final BitSet absoluteURI = new BitSet(256);
     // Static initializer for absoluteURI
     static {
         absoluteURI.or(scheme);
         absoluteURI.set(':');
         absoluteURI.or(hier_part);
         absoluteURI.or(opaque_part);
     }
 
 
     /**
      * BitSet for URI-reference.
      * <p><blockquote><pre>
      * URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
      * </pre></blockquote><p>
      */
     protected static final BitSet URI_reference = new BitSet(256);
     // Static initializer for URI_reference
     static {
         URI_reference.or(absoluteURI);
         URI_reference.or(relativeURI);
         URI_reference.set('#');
         URI_reference.or(fragment);
     }
 
     // ---------------------------- Characters disallowed within the URI syntax
     // Excluded US-ASCII Characters are like control, space, delims and unwise
 
     /**
      * BitSet for control.
      */
     public static final BitSet control = new BitSet(256);
     // Static initializer for control
     static {
         for (int i = 0; i <= 0x1F; i++) {
             control.set(i);
         }
         control.set(0x7F);
     }
 
     /**
      * BitSet for space.
      */
     public static final BitSet space = new BitSet(256);
     // Static initializer for space
     static {
         space.set(0x20);
     }
 
 
     /**
      * BitSet for delims.
      */
     public static final BitSet delims = new BitSet(256);
     // Static initializer for delims
     static {
         delims.set('<');
         delims.set('>');
         delims.set('#');
         delims.set('%');
         delims.set('"');
     }
 
 
     /**
      * BitSet for unwise.
      */
     public static final BitSet unwise = new BitSet(256);
     // Static initializer for unwise
     static {
         unwise.set('{');
         unwise.set('}');
         unwise.set('|');
         unwise.set('\\');
         unwise.set('^');
         unwise.set('[');
         unwise.set(']');
         unwise.set('`');
     }
 
 
     /**
      * Disallowed rel_path before escaping.
      */
     public static final BitSet disallowed_rel_path = new BitSet(256);
     // Static initializer for disallowed_rel_path
     static {
         disallowed_rel_path.or(uric);
         disallowed_rel_path.andNot(rel_path);
     }
 
 
     /**
      * Disallowed opaque_part before escaping.
      */
     public static final BitSet disallowed_opaque_part = new BitSet(256);
     // Static initializer for disallowed_opaque_part
     static {
         disallowed_opaque_part.or(uric);
         disallowed_opaque_part.andNot(opaque_part);
     }
 
     // ----------------------- Characters allowed within and for each component
 
     /**
      * Those characters that are allowed for the authority component.
      */
     public static final BitSet allowed_authority = new BitSet(256);
     // Static initializer for allowed_authority
     static {
         allowed_authority.or(authority);
         allowed_authority.clear('%');
     }
 
 
     /**
      * Those characters that are allowed for the opaque_part.
      */
     public static final BitSet allowed_opaque_part = new BitSet(256);
     // Static initializer for allowed_opaque_part 
     static {
         allowed_opaque_part.or(opaque_part);
         allowed_opaque_part.clear('%');
     }
 
 
     /**
      * Those characters that are allowed for the reg_name.
      */
     public static final BitSet allowed_reg_name = new BitSet(256);
     // Static initializer for allowed_reg_name 
     static {
         allowed_reg_name.or(reg_name);
         // allowed_reg_name.andNot(percent);
         allowed_reg_name.clear('%');
     }
 
 
     /**
      * Those characters that are allowed for the userinfo component.
      */
     public static final BitSet allowed_userinfo = new BitSet(256);
     // Static initializer for allowed_userinfo
     static {
         allowed_userinfo.or(userinfo);
         // allowed_userinfo.andNot(percent);
         allowed_userinfo.clear('%');
     }
 
 
     /**
      * Those characters that are allowed for within the userinfo component.
      */
     public static final BitSet allowed_within_userinfo = new BitSet(256);
     // Static initializer for allowed_within_userinfo
     static {
         allowed_within_userinfo.or(within_userinfo);
         allowed_within_userinfo.clear('%');
     }
 
 
     /**
      * Those characters that are allowed for the IPv6reference component.
      * The characters '[', ']' in IPv6reference should be excluded.
      */
     public static final BitSet allowed_IPv6reference = new BitSet(256);
     // Static initializer for allowed_IPv6reference
     static {
         allowed_IPv6reference.or(IPv6reference);
         // allowed_IPv6reference.andNot(unwise);
         allowed_IPv6reference.clear('[');
         allowed_IPv6reference.clear(']');
     }
 
 
     /**
      * Those characters that are allowed for the host component.
      * The characters '[', ']' in IPv6reference should be excluded.
      */
     public static final BitSet allowed_host = new BitSet(256);
     // Static initializer for allowed_host
     static {
         allowed_host.or(hostname);
         allowed_host.or(allowed_IPv6reference);
     }
 
 
     /**
      * Those characters that are allowed for the authority component.
      */
     public static final BitSet allowed_within_authority = new BitSet(256);
     // Static initializer for allowed_within_authority
     static {
         allowed_within_authority.or(server);
         allowed_within_authority.or(reg_name);
         allowed_within_authority.clear(';');
         allowed_within_authority.clear(':');
         allowed_within_authority.clear('@');
         allowed_within_authority.clear('?');
         allowed_within_authority.clear('/');
     }
 
 
     /**
      * Those characters that are allowed for the abs_path.
      */
     public static final BitSet allowed_abs_path = new BitSet(256);
     // Static initializer for allowed_abs_path
     static {
         allowed_abs_path.or(abs_path);
         // allowed_abs_path.set('/');  // aleady included
         allowed_abs_path.andNot(percent);
     }
 
 
     /**
      * Those characters that are allowed for the rel_path.
      */
     public static final BitSet allowed_rel_path = new BitSet(256);
     // Static initializer for allowed_rel_path
     static {
         allowed_rel_path.or(rel_path);
         allowed_rel_path.clear('%');
     }
 
 
     /**
      * Those characters that are allowed within the path.
      */
     public static final BitSet allowed_within_path = new BitSet(256);
     // Static initializer for allowed_within_path
     static {
         allowed_within_path.or(abs_path);
         allowed_within_path.clear('/');
         allowed_within_path.clear(';');
         allowed_within_path.clear('=');
         allowed_within_path.clear('?');
     }
 
 
     /**
      * Those characters that are allowed for the query component.
      */
     public static final BitSet allowed_query = new BitSet(256);
     // Static initializer for allowed_query
     static {
         allowed_query.or(uric);
         allowed_query.clear('%');
     }
 
 
     /**
      * Those characters that are allowed within the query component.
      */
     public static final BitSet allowed_within_query = new BitSet(256);
     // Static initializer for allowed_within_query
     static {
         allowed_within_query.or(allowed_query);
         allowed_within_query.andNot(reserved); // excluded 'reserved'
         allowed_within_query.clear('#'); // avoid confict with the fragment
     }
 
 
     /**
      * Those characters that are allowed for the fragment component.
      */
     public static final BitSet allowed_fragment = new BitSet(256);
     // Static initializer for allowed_fragment
     static {
         allowed_fragment.or(uric);
         allowed_fragment.clear('%');
     }
 
     // ------------------------------------------- Flags for this URI-reference
 
     // URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     // absoluteURI   = scheme ":" ( hier_part | opaque_part )
     protected boolean _is_hier_part;
     protected boolean _is_opaque_part;
     // relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ] 
     // hier_part     = ( net_path | abs_path ) [ "?" query ]
     protected boolean _is_net_path;
     protected boolean _is_abs_path;
     protected boolean _is_rel_path;
     // net_path      = "//" authority [ abs_path ] 
     // authority     = server | reg_name
     protected boolean _is_reg_name;
     protected boolean _is_server;  // = _has_server
     // server        = [ [ userinfo "@" ] hostport ]
     // host          = hostname | IPv4address | IPv6reference
     protected boolean _is_hostname;
     protected boolean _is_IPv4address;
     protected boolean _is_IPv6reference;
 
     // ------------------------------------------ Character and escape encoding
     
     /**
      * Encode with the default protocol charset.
      *
      * @param original the original character sequence
      * @param allowed those characters that are allowed within a component
      * @return URI character sequence
      * @exception IOException null component or unsupported character encoding
      */
     protected static char[] encode(String original, BitSet allowed)
         throws IOException {
 
         return encode(original, allowed, _protocolCharset);
     }
 
 
     /**
      * Encodes URI string.
      *
      * This is a two mapping, one from original characters to octets, and
      * subsequently a second from octets to URI characters:
      * <p><blockquote><pre>
      *   original character sequence->octet sequence->URI character sequence
      * </pre></blockquote><p>
      *
      * An escaped octet is encoded as a character triplet, consisting of the
      * percent character "%" followed by the two hexadecimal digits
      * representing the octet code. For example, "%20" is the escaped
      * encoding for the US-ASCII space character.
      * <p>
      * Conversion from the local filesystem character set to UTF-8 will
      * normally involve a two step process. First convert the local character
      * set to the UCS; then convert the UCS to UTF-8.
      * The first step in the process can be performed by maintaining a mapping
      * table that includes the local character set code and the corresponding
      * UCS code.
      * The next step is to convert the UCS character code to the UTF-8 encoding.
      * <p>
      * Mapping between vendor codepages can be done in a very similar manner
      * as described above.
      * <p>
      * The only time escape encodings can allowedly be made is when a URI is
      * being created from its component parts.  The escape and validate methods
      * are internally performed within this method.
      *
      * @param original the original character sequence
      * @param allowed those characters that are allowed within a component
      * @param charset the protocol charset
      * @return URI character sequence
      * @exception IOException null component or unsupported character encoding
      */
     protected static char[] encode(String original, BitSet allowed,
             String charset) throws IOException {
 
         // encode original to uri characters.
         if (original == null) {
             throw new IOException(/*IOException.PARSING,*/ "URI: null");
         }
         // escape octet to uri characters.
         if (allowed == null) {
             throw new IOException(/*IOException.PARSING,*/
                     "URI: null allowed characters");
         }
         byte[] octets;
         try {
             octets = original.getBytes(charset);
         } catch (UnsupportedEncodingException error) {
             throw new IOException(/*IOException.UNSUPPORTED_ENCODING,*/ "Unsupported Encoding: " + charset);
         }
         StringBuffer buf = new StringBuffer(octets.length);
         for (int i = 0; i < octets.length; i++) {
             char c = (char) octets[i];
             if (allowed.get(c)) {
                 buf.append(c);
             } else {
                 buf.append('%');
                 byte b = octets[i]; // use the original byte value
                 char hexadecimal = Character.forDigit((b >> 4) & 0xF, 16);
                 buf.append(Character.toUpperCase(hexadecimal)); // high
                 hexadecimal = Character.forDigit(b & 0xF, 16);
                 buf.append(Character.toUpperCase(hexadecimal)); // low
             }
         }
 
         return buf.toString().toCharArray();
     }
 
 
     /**
      * Decode with the default protocol charset.
      *
      * @param component the URI character sequence
      * @return original character sequence
      * @exception IOException incomplete trailing escape pattern
      * or unsupported character encoding
      */
     protected static String decode(char[] component) throws IOException {
         return decode(component, _protocolCharset);
     }
 
 
     /**
      * Decodes URI encoded string.
      *
      * This is a two mapping, one from URI characters to octets, and
      * subsequently a second from octets to original characters:
      * <p><blockquote><pre>
      *   URI character sequence->octet sequence->original character sequence
      * </pre></blockquote><p>
      *
      * A URI must be separated into its components before the escaped
      * characters within those components can be allowedly decoded.
      * <p>
      * Notice that there is a chance that URI characters that are non UTF-8
      * may be parsed as valid UTF-8.  A recent non-scientific analysis found
      * that EUC encoded Japanese words had a 2.7% false reading; SJIS had a
      * 0.0005% false reading; other encoding such as ASCII or KOI-8 have a 0%
      * false reading.
      * <p>
      * The percent "%" character always has the reserved purpose of being
      * the escape indicator, it must be escaped as "%25" in order to be used
      * as data within a URI.
      * <p>
      * The unescape method is internally performed within this method.
      *
      * @param component the URI character sequence
      * @param charset the protocol charset
      * @return original character sequence
      * @exception IOException incomplete trailing escape pattern
      * or unsupported character encoding
      */
     protected static String decode(char[] component, String charset)
         throws IOException {
 
         // unescape uri characters to octets
         if (component == null)  return null;
 
         byte[] octets;
         try {
             octets = new String(component).getBytes(charset);
         } catch (UnsupportedEncodingException error) {
             throw new IOException(/* IOException.UNSUPPORTED_ENCODING, */
                     "URI: not supported " + charset + " encoding");
         }
         int length = octets.length;
         int oi = 0; // output index
         for (int ii = 0; ii < length; oi++) {
             byte aByte = (byte) octets[ii++];
             if (aByte == '%' && ii+2 <= length)  {
                 byte high = (byte) Character.digit((char) octets[ii++], 16);
                 byte low = (byte) Character.digit((char) octets[ii++], 16);
                 if (high == -1 || low == -1) {
                     throw new IOException(/* IOException.ESCAPING, */
                             "URI: incomplete trailing escape pattern");
                             
                 }
                 aByte = (byte) ((high << 4) + low);
             }
             octets[oi] = (byte) aByte;
         }
 
         String result;
         try {
             result = new String(octets, 0, oi, charset);
         } catch (UnsupportedEncodingException error) {
             throw new IOException(/* IOException.UNSUPPORTED_ENCODING, */
                     "URI: not supported " + charset + " encoding");
         }
 
         return result;
     }
 
 
     /**
      * Pre-validate the unescaped URI string within a specific component.
      *
      * @param component the component string within the component
      * @param disallowed those characters disallowed within the component
      * @return if true, it doesn't have the disallowed characters
      * if false, the component is undefined or an incorrect one
      */
     protected boolean prevalidate(String component, BitSet disallowed) {
         // prevalidate the given component by disallowed characters
         if (component == null) {
             return false; // undefined
         }
         char[] target = component.toCharArray();
         for (int i = 0; i < target.length; i++) {
             if (disallowed.get(target[i])) {
                 return false;
             }
         }
         return true;
     }
 
 
     /**
      * Validate the URI characters within a specific component.
      * The component must be performed after escape encoding. Or it doesn't
      * include escaped characters.
      *
      * @param component the characters sequence within the component
      * @param generous those characters that are allowed within a component
      * @return if true, it's the correct URI character sequence
      */
     protected boolean validate(char[] component, BitSet generous) {
         // validate each component by generous characters
         return validate(component, 0, -1, generous);
     }
 
 
     /**
      * Validate the URI characters within a specific component.
      * The component must be performed after escape encoding. Or it doesn't
      * include escaped characters.
      * <p>
      * It's not that much strict, generous.  The strict validation might be 
      * performed before being called this method.
      *
      * @param component the characters sequence within the component
      * @param soffset the starting offset of the given component
      * @param eoffset the ending offset of the given component
      * if -1, it means the length of the component
      * @param generous those characters that are allowed within a component
      * @return if true, it's the correct URI character sequence
      * @throws NullPointerException null component
      */
     protected boolean validate(char[] component, int soffset, int eoffset,
             BitSet generous) {
         // validate each component by generous characters
         if (eoffset == -1) {
             eoffset = component.length -1;
         }
         for (int i = soffset; i <= eoffset; i++) {
             if (!generous.get(component[i])) return false;
         }
         return true;
     }
 
 
     /**
      * In order to avoid any possilbity of conflict with non-ASCII characters,
      * Parse a URI reference as a <code>String</code> with the character
      * encoding of the local system or the document.
      * <p>
      * The following line is the regular expression for breaking-down a URI
      * reference into its components.
      * <p><blockquote><pre>
      *   ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
      *    12            3  4          5       6  7        8 9
      * </pre></blockquote><p>
      * For example, matching the above expression to
      *   http://jakarta.apache.org/ietf/uri/#Related
      * results in the following subexpression matches:
      * <p><blockquote><pre>
      *               $1 = http:
      *  scheme    =  $2 = http
      *               $3 = //jakarta.apache.org
      *  authority =  $4 = jakarta.apache.org
      *  path      =  $5 = /ietf/uri/
      *               $6 = <undefined>
      *  query     =  $7 = <undefined>
      *               $8 = #Related
      *  fragment  =  $9 = Related
      * </pre></blockquote><p>
      *
      * @param original the original character sequence
      * @param escaped <code>true</code> if <code>original</code> is escaped
      * @return the original character sequence
      * @exception IOException
      */
     protected void parseUriReference(String original, boolean escaped)
         throws IOException {
 
         // validate and contruct the URI character sequence
         if (original == null || original.length() == 0) {
             throw new IOException("URI-Reference required");
         }
 
         /** @
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          */
         String tmp = original.trim();
         
         /**
          * The length of the string sequence of characters.
          * It may not be equal to the length of the byte array.
          */
         int length = tmp.length();
 
         /**
          * Remove the delimiters like angle brackets around an URI.
          */
         char[] firstDelimiter = { tmp.charAt(0) };
         if (validate(firstDelimiter, delims)) {
             if (length >= 2) {
                 char[] lastDelimiter = { tmp.charAt(length - 1) };
                 if (validate(lastDelimiter, delims)) {
                     tmp = tmp.substring(1, length - 1);
                     length = length - 2;
                 }
             }
         }
 
         /**
          * The starting index
          */
         int from = 0;
 
         /**
          * The test flag whether the URI is started from the path component.
          */
         boolean isStartedFromPath = false;
         int atColon = tmp.indexOf(':');
         int atSlash = tmp.indexOf('/');
         if (atColon < 0 || (atSlash >= 0 && atSlash < atColon)) {
             isStartedFromPath = true;
         }
 
         /**
          * <p><blockquote><pre>
          *     @@@@@@@@
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         int at = indexFirstOf(tmp, isStartedFromPath ? "/?#" : ":/?#", from);
         if (at == -1) at = 0;
 
         /**
          * Parse the scheme.
          * <p><blockquote><pre>
          *  scheme    =  $2 = http
          *              @
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         if (at < length && tmp.charAt(at) == ':') {
             char[] target = tmp.substring(0, at).toLowerCase().toCharArray();
             if (validate(target, scheme)) {
                 _scheme = target;
             } else {
                 throw new IOException("incorrect scheme");
             }
             from = ++at;
         }
 
         /**
          * Parse the authority component.
          * <p><blockquote><pre>
          *  authority =  $4 = jakarta.apache.org
          *                  @@
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         // Reset flags
         _is_net_path = _is_abs_path = _is_rel_path = _is_hier_part = false;
         if (0 <= at && at < length && tmp.charAt(at) == '/') {
             // Set flag
             _is_hier_part = true;
             if (at + 2 < length && tmp.charAt(at + 1) == '/') {
                 // the temporary index to start the search from
                 int next = indexFirstOf(tmp, "/?#", at + 2);
                 if (next == -1) {
                     next = (tmp.substring(at + 2).length() == 0) ? at + 2 :
                     tmp.length();
                 }
                 parseAuthority(tmp.substring(at + 2, next), escaped);
                 from = at = next;
                 // Set flag
                 _is_net_path = true;
             }
             if (from == at) {
                 // Set flag
                 _is_abs_path = true;
             }
         }
 
         /**
          * Parse the path component.
          * <p><blockquote><pre>
          *  path      =  $5 = /ietf/uri/
          *                                @@@@@@
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         if (from < length) {
             // rel_path = rel_segment [ abs_path ]
             int next = indexFirstOf(tmp, "?#", from);
             if (next == -1) {
                 next = tmp.length();
             }
             if (!_is_abs_path) {
                 if (!escaped && prevalidate(tmp.substring(from, next),
                             disallowed_rel_path) || escaped &&
                         validate(tmp.substring(from, next).toCharArray(),
                             rel_path)) {
                     // Set flag
                     _is_rel_path = true;
                 } else if (!escaped && prevalidate(tmp.substring(from, next),
                             disallowed_opaque_part) || escaped &&
                         validate(tmp.substring(from, next).toCharArray(),
                             opaque_part)) {
                     // Set flag
                     _is_opaque_part = true;
                 } else {
                     // the path component may be empty
                     _path = null;
                 }
             }
             setPath(tmp.substring(from, next));
             at = next;
         }
 
         /**
          * Parse the query component.
          * <p><blockquote><pre>
          *  query     =  $7 = <undefined>
          *                                        @@@@@@@@@
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         if (0 <= at && at+1 < length && tmp.charAt(at) == '?') {
             int next = tmp.indexOf('#', at + 1);
             if (next == -1) {
                 next = tmp.length();
             }
             _query = (escaped) ? tmp.substring(at + 1, next).toCharArray() :
             encode(tmp.substring(at + 1, next), allowed_query);
             at = next;
         }
 
         /**
          * Parse the fragment component.
          * <p><blockquote><pre>
          *  fragment  =  $9 = Related
          *                                                   @@@@@@@@
          *  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
          * </pre></blockquote><p>
          */
         if (0 <= at && at+1 < length && tmp.charAt(at) == '#') {
             _fragment = (escaped) ? tmp.substring(at + 1).toCharArray() :
             encode(tmp.substring(at + 1), allowed_fragment);
         }
 
         // set this URI.
         setUriReference();
     }
 
 
     /**
      * Get the earlier index that to be searched for the first occurrance in
      * one of any of the given string.
      *
      * @param s the string to be indexed
      * @param delims the delimiters used to index
      * @return the earlier index if there are delimiters
      */
     protected int indexFirstOf(String s, String delims) {
         return indexFirstOf(s, delims, -1);
     }
 
 
     /**
      * Get the earlier index that to be searched for the first occurrance in
      * one of any of the given string.
      *
      * @param s the string to be indexed
      * @param delims the delimiters used to index
      * @param offset the from index
      * @return the earlier index if there are delimiters
      */
     protected int indexFirstOf(String s, String delims, int offset) {
         if (s == null || s.length() == 0) {
             return -1;
         }
         if (delims == null || delims.length() == 0) {
             return -1;
         }
         // check boundaries
         if (offset < 0) {
             offset = 0;
         } else if (offset > s.length()) {
             return -1;
         }
         // s is never null
         int min = s.length();
         char[] delim = delims.toCharArray();
         for (int i = 0; i < delim.length; i++) {
             int at = s.indexOf(delim[i], offset);
             if (at >= 0 && at < min) {
                 min = at;
             }
         }
         return (min == s.length()) ? -1 : min;
     }
 
 
     /**
      * Get the earlier index that to be searched for the first occurrance in
      * one of any of the given array.
      *
      * @param s the character array to be indexed
      * @param delim the delimiter used to index
      * @return the ealier index if there are a delimiter
      */
     protected int indexFirstOf(char[] s, char delim) {
         return indexFirstOf(s, delim, 0);
     }
 
 
     /**
      * Get the earlier index that to be searched for the first occurrance in
      * one of any of the given array.
      *
      * @param s the character array to be indexed
      * @param delim the delimiter used to index
      * @return the ealier index if there is a delimiter
      */
     protected int indexFirstOf(char[] s, char delim, int offset) {
         if (s == null || s.length == 0) {
             return -1;
         }
         // check boundaries
         if (offset < 0) {
             offset = 0;
         } else if (offset > s.length) {
             return -1;
         }
         for (int i = offset; i < s.length; i++) {
             if (s[i] == delim) {
                 return i;
             }
         }
         return -1;
     }
 
 
     /**
      * Parse the authority component.
      *
      * @param original the original character sequence of authority component
      * @param escaped <code>true</code> if <code>original</code> is escaped
      * @exception IOException
      */
     protected void parseAuthority(String original, boolean escaped)
         throws IOException {
 
         // Reset flags
         _is_reg_name = _is_server =
         _is_hostname = _is_IPv4address = _is_IPv6reference = false;
 
         boolean has_port = true;
         int from = 0;
         int next = original.indexOf('@');
         if (next != -1) { // neither -1 and 0
             // each protocol extented from URI supports the specific userinfo
             _userinfo = (escaped) ? original.substring(0, next).toCharArray() :
             encode(original.substring(0, next), allowed_userinfo);
             from = next + 1;
         }
         next = original.indexOf('[', from);
         if (next >= from) {
             next = original.indexOf(']', from);
             if (next == -1) {
                 throw new IOException(/* IOException.PARSING,*/ "URI: IPv6reference");
             } else {
                 next++;
             }
             // In IPv6reference, '[', ']' should be excluded
             _host = (escaped) ? original.substring(from, next).toCharArray() :
             encode(original.substring(from, next), allowed_IPv6reference);
             // Set flag
             _is_IPv6reference = true;
         } else { // only for !_is_IPv6reference
             next = original.indexOf(':', from);
             if (next == -1) {
                 next = original.length();
                 has_port = false;
             }
             // REMINDME: it doesn't need the pre-validation
             _host = original.substring(from, next).toCharArray();
             if (validate(_host, IPv4address)) {
                 // Set flag
                 _is_IPv4address = true;
             } else if (validate(_host, hostname)) {
                 // Set flag
                 _is_hostname = true;
             } else {
                 // Set flag
                 _is_reg_name = true;
             }
         }
         if (_is_reg_name) {
             // Reset flags for a server-based naming authority
             _is_server = _is_hostname = _is_IPv4address =
             _is_IPv6reference = false;
             // set a registry-based naming authority
             _authority = (escaped) ? original.toString().toCharArray() :
             encode(original.toString(), allowed_reg_name);
         } else {
             if (original.length()-1 > next && has_port &&
                     original.charAt(next) == ':') { // not empty
                 from = next + 1;
                 try {
                     _port = Integer.parseInt(original.substring(from));
                 } catch (NumberFormatException error) {
                     throw new IOException(/*IOException.PARSING, */
                             "URI: invalid port number");
                 }
             }
             // set a server-based naming authority
             StringBuffer buf = new StringBuffer();
             if (_userinfo != null) { // has_userinfo
                 buf.append(_userinfo);
                 buf.append('@');
             }
             if (_host != null) {
                 buf.append(_host);
                 if (_port != -1) {
                     buf.append(':');
                     buf.append(_port);
                 }
             }
             _authority = buf.toString().toCharArray();
             // Set flag
             _is_server = true;
         }
     }
 
 
     /**
      * Once it's parsed successfully, set this URI.
      *
      * @see #getRawURI
      */
     protected void setUriReference() {
         // set _uri
         StringBuffer buf = new StringBuffer();
         // ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
         if (_scheme != null) {
             buf.append(_scheme);
             buf.append(':');
         }
         if (_is_net_path) {
             buf.append("//");
             if (_authority != null) { // has_authority
                 if (_userinfo != null) { // by default, remove userinfo part
                     if (_host != null) {
                         buf.append(_host);
                         if (_port != -1) {
                             buf.append(':');
                             buf.append(_port);
                         }
                     }
                 } else {
                     buf.append(_authority);
                 }
             }
         }
         if (_opaque != null && _is_opaque_part) {
             buf.append(_opaque);
         } else if (_path != null) {
             // _is_hier_part or _is_relativeURI
             if (_path.length != 0) {
                 buf.append(_path);
             }
         }
         if (_query != null) { // has_query
             buf.append('?');
             buf.append(_query);
         }
         if (_fragment != null) { // has_fragment
             buf.append('#');
             buf.append(_fragment);
         }
 
         _uri = buf.toString().toCharArray();
     }
 
     // ----------------------------------------------------------- Test methods
   
 
     /**
      * Tell whether or not this URI is absolute.
      *
      * @return true iif this URI is absoluteURI
      */
     public boolean isAbsoluteURI() {
         return (_scheme != null);
     }
   
 
     /**
      * Tell whether or not this URI is relative.
      *
      * @return true iif this URI is relativeURI
      */
     public boolean isRelativeURI() {
         return (_scheme == null);
     }
 
 
     /**
      * Tell whether or not the absoluteURI of this URI is hier_part.
      *
      * @return true iif the absoluteURI is hier_part
      */
     public boolean isHierPart() {
         return _is_hier_part;
     }
 
 
     /**
      * Tell whether or not the absoluteURI of this URI is opaque_part.
      *
      * @return true iif the absoluteURI is opaque_part
      */
     public boolean isOpaquePart() {
         return _is_opaque_part;
     }
 
 
     /**
      * Tell whether or not the relativeURI or heir_part of this URI is net_path.
      * It's the same function as the has_authority() method.
      *
      * @return true iif the relativeURI or heir_part is net_path
      * @see #hasAuthority
      */
     public boolean isNetPath() {
         return _is_net_path || (_authority != null);
     }
 
 
     /**
      * Tell whether or not the relativeURI or hier_part of this URI is abs_path.
      *
      * @return true iif the relativeURI or hier_part is abs_path
      */
     public boolean isAbsPath() {
         return _is_abs_path;
     }
 
 
     /**
      * Tell whether or not the relativeURI of this URI is rel_path.
      *
      * @return true iif the relativeURI is rel_path
      */
     public boolean isRelPath() {
         return _is_rel_path;
     }
 
 
     /**
      * Tell whether or not this URI has authority.
      * It's the same function as the is_net_path() method.
      *
      * @return true iif this URI has authority
      * @see #isNetPath
      */
     public boolean hasAuthority() {
         return (_authority != null) || _is_net_path;
     }
 
     /**
      * Tell whether or not the authority component of this URI is reg_name.
      *
      * @return true iif the authority component is reg_name
      */
     public boolean isRegName() {
         return _is_reg_name;
     }
   
 
     /**
      * Tell whether or not the authority component of this URI is server.
      *
      * @return true iif the authority component is server
      */
     public boolean isServer() {
         return _is_server;
     }
   
 
     /**
      * Tell whether or not this URI has userinfo.
      *
      * @return true iif this URI has userinfo
      */
     public boolean hasUserinfo() {
         return (_userinfo != null);
     }
   
 
     /**
      * Tell whether or not the host part of this URI is hostname.
      *
      * @return true iif the host part is hostname
      */
     public boolean isHostname() {
         return _is_hostname;
     }
 
 
     /**
      * Tell whether or not the host part of this URI is IPv4address.
      *
      * @return true iif the host part is IPv4address
      */
     public boolean isIPv4address() {
         return _is_IPv4address;
     }
 
 
     /**
      * Tell whether or not the host part of this URI is IPv6reference.
      *
      * @return true iif the host part is IPv6reference
      */
     public boolean isIPv6reference() {
         return _is_IPv6reference;
     }
 
 
     /**
      * Tell whether or not this URI has query.
      *
      * @return true iif this URI has query
      */
     public boolean hasQuery() {
         return (_query != null);
     }
    
 
     /**
      * Tell whether or not this URI has fragment.
      *
      * @return true iif this URI has fragment
      */
     public boolean hasFragment() {
         return (_fragment != null);
     }
    
    
     // ---------------------------------------------------------------- Charset
 
 
     /**
      * Set the default charset of the protocol.
      * <p>
      * The character set used to store files SHALL remain a local decision and
      * MAY depend on the capability of local operating systems. Prior to the
      * exchange of URIs they SHOULD be converted into a ISO/IEC 10646 format
      * and UTF-8 encoded. This approach, while allowing international exchange
      * of URIs, will still allow backward compatibility with older systems
      * because the code set positions for ASCII characters are identical to the
      * one byte sequence in UTF-8.
      * <p>
      * An individual URI scheme may require a single charset, define a default
      * charset, or provide a way to indicate the charset used.
      *
      * @param charset the default charset for each protocol
      */
     public static void setProtocolCharset(String charset) {
         _protocolCharset = charset;
     }
 
 
     /**
      * Get the default charset of the protocol.
      * <p>
      * An individual URI scheme may require a single charset, define a default
      * charset, or provide a way to indicate the charset used.
      * <p>
      * To work globally either requires support of a number of character sets
      * and to be able to convert between them, or the use of a single preferred
      * character set.
      * For support of global compatibility it is STRONGLY RECOMMENDED that
      * clients and servers use UTF-8 encoding when exchanging URIs.
      *
      * @return the charset string
      */
     public static String getProtocolCharset() {
         return _protocolCharset;
     }
 
 
     /**
      * Set the default charset of the document.
      * <p>
      * Notice that it will be possible to contain mixed characters (e.g.
      * ftp://host/KoreanNamespace/ChineseResource). To handle the Bi-directional
      * display of these character sets, the protocol charset could be simply
      * used again. Because it's not yet implemented that the insertion of BIDI
      * control characters at different points during composition is extracted.
      *
      * @param charset the default charset for the document
      */
     public static void setDocumentCharset(String charset) {
         _documentCharset = charset;
     }
 
 
     /**
      * Get the default charset of the document.
      *
      * @return the charset string
      */
     public static String getDocumentCharset() {
         return _documentCharset;
     }
 
     // ------------------------------------------------------------- The scheme
 
     /**
      * Get the scheme.
      *
      * @return the scheme
      */
     public char[] getRawScheme() {
         return _scheme;
     }
 
 
     /**
      * Get the scheme.
      *
      * @return the scheme
      * null if undefined scheme
      */
     public String getScheme() {
         return (_scheme == null) ? null : new String(_scheme);
     }
 
     // ---------------------------------------------------------- The authority
 
     /**
      * Set the authority.  It can be one type of server, hostport, hostname,
      * IPv4address, IPv6reference and reg_name.
      * <p><blockquote><pre>
      *   authority     = server | reg_name
      * </pre></blockquote><p>
      *
      * @param escapedAuthority the raw escaped authority
      * @exception IOException
      * @throws NullPointerException null authority
      */
     public void setRawAuthority(char[] escapedAuthority) throws IOException {
         parseAuthority(new String(escapedAuthority), true);
         setUriReference();
     }
 
 
     /**
      * Set the authority.  It can be one type of server, hostport, hostname,
      * IPv4address, IPv6reference and reg_name.
      * Note that there is no setAuthority method by the escape encoding reason.
      *
      * @param escapedAuthority the escaped authority string
      * @exception IOException
      */
     public void setEscapedAuthority(String escapedAuthority)
         throws IOException {
 
         parseAuthority(escapedAuthority, true);
         setUriReference();
     }
 
 
     /**
      * Get the raw-escaped authority.
      *
      * @return the raw-escaped authority
      */
     public char[] getRawAuthority() {
         return _authority;
     }
 
 
     /**
      * Get the escaped authority.
      *
      * @return the escaped authority
      */
     public String getEscapedAuthority() {
         return (_authority == null) ? null : new String(_authority);
     }
 
 
     /**
      * Get the authority.
      *
      * @return the authority
      * @exception IOException
      * @see #decode
      */
     public String getAuthority() throws IOException {
         return (_authority == null) ? null : decode(_authority);
     }
 
     // ----------------------------------------------------------- The userinfo
 
     /**
      * Get the raw-escaped userinfo.
      *
      * @return the raw-escaped userinfo
      * @see #getAuthority
      */
     public char[] getRawUserinfo() {
         return _userinfo;
     }
 
 
     /**
      * Get the escaped userinfo.
      *
      * @return the escaped userinfo
      * @see #getAuthority
      */
     public String getEscapedUserinfo() {
         return (_userinfo == null) ? null : new String(_userinfo);
     }
 
 
     /**
      * Get the userinfo.
      *
      * @return the userinfo
      * @exception IOException
      * @see #decode
      * @see #getAuthority
      */
     public String getUserinfo() throws IOException {
         return (_userinfo == null) ? null : decode(_userinfo);
     }
 
     // --------------------------------------------------------------- The host
 
     /**
      * Get the host.
      * <p><blockquote><pre>
      *   host          = hostname | IPv4address | IPv6reference
      * </pre></blockquote><p>
      *
      * @return the host
      * @see #getAuthority
      */
     public char[] getRawHost() {
         return _host;
     }
 
 
     /**
      * Get the host.
      * <p><blockquote><pre>
      *   host          = hostname | IPv4address | IPv6reference
      * </pre></blockquote><p>
      *
      * @return the host
      * @exception IOException
      * @see #decode
      * @see #getAuthority
      */
     public String getHost() throws IOException {
         return decode(_host);
     }
 
     // --------------------------------------------------------------- The port
 
     /**
      * Get the port.  In order to get the specfic default port, the specific
      * protocol-supported class extended from the URI class should be used.
      * It has the server-based naming authority.
      *
      * @return the port
      * if -1, it has the default port for the scheme or the server-based
      * naming authority is not supported in the specific URI.
      */
     public int getPort() {
         return _port;
     }
 
     // --------------------------------------------------------------- The path
 
     /**
      * Set the path.   The method couldn't be used by API programmers.
      *
      * @param path the path string
      * @exception IOException set incorrectly or fragment only
      * @see #encode
      */
     protected void setPath(String path) throws IOException {
 
         // set path
         if (_is_net_path || _is_abs_path) {
             _path = encode(path, allowed_abs_path);
         } else if (_is_rel_path) {
             StringBuffer buff = new StringBuffer(path.length());
             int at = path.indexOf('/');
             if (at > 0) {  // never 0
                 buff.append(encode(path.substring(0, at), allowed_rel_path));
                 buff.append(encode(path.substring(at), allowed_abs_path));
             } else {
                 buff.append(encode(path, allowed_rel_path));
             }
             _path = buff.toString().toCharArray();
         } else if (_is_opaque_part) {
             _opaque = encode(path, allowed_opaque_part);
         } else {
             throw new IOException(/*IOException.PARSING, */"URI: incorrect path");
         }
     }
 
 
     /**
      * Resolve the base and relative path.
      *
      * @param base_path a character array of the base_path
      * @param rel_path a character array of the rel_path
      * @return the resolved path
      */
     protected char[] resolvePath(char[] base_path, char[] rel_path) {
 
         // REMINDME: paths are never null
         String base = (base_path == null) ? "" : new String(base_path);
         int at = base.lastIndexOf('/');
         if (at != -1) {
             base_path = base.substring(0, at + 1).toCharArray();
         }
         // _path could be empty
         if (rel_path == null || rel_path.length == 0) {
             return normalize(base_path);
         } else if (rel_path[0] == '/') {
             return rel_path;
         } else {
             StringBuffer buff = new StringBuffer(base.length() +
                 rel_path.length);
             if (at != -1) {
                 buff.append(base.substring(0, at + 1));
                 buff.append(rel_path);
             }
             return normalize(buff.toString().toCharArray());
         }
     }
 
 
     /**
      * Get the raw-escaped current hierarchy level in the given path.
      * If the last namespace is a collection, the slash mark ('/') should be
      * ended with at the last character of the path string.
      *
      * @param path the path
      * @return the current hierarchy level
      * @exception IOException no hierarchy level
      */
     protected char[] getRawCurrentHierPath(char[] path) throws IOException {
 
         if (_is_opaque_part) {
             throw new IOException(/*IOException.PARSING,*/ "URI: no hierarchy level");
         }
         if (path == null) {
             throw new IOException(/*IOException.PARSING,*/ "URI: emtpy path");
         }
         String buff = new String(path);
         int first = buff.indexOf('/');
         int last = buff.lastIndexOf('/');
         if (last == 0) {
             return rootPath;
         } else if (first != last && last != -1) {
             return buff.substring(0, last).toCharArray();
         }
         // FIXME: it could be a document on the server side
         return path;
     }
 
 
     /**
      * Get the raw-escaped current hierarchy level.
      *
      * @return the raw-escaped current hierarchy level
      * @exception IOException no hierarchy level
      */
     public char[] getRawCurrentHierPath() throws IOException {
         return (_path == null) ? null : getRawCurrentHierPath(_path);
     }
  
 
     /**
      * Get the escaped current hierarchy level.
      *
      * @return the escaped current hierarchy level
      * @exception IOException no hierarchy level
      */
     public String getEscapedCurrentHierPath() throws IOException {
         char[] path = getRawCurrentHierPath();
         return (path == null) ? null : new String(path);
     }
  
 
     /**
      * Get the current hierarchy level.
      *
      * @return the current hierarchy level
      * @exception IOException
      * @see #decode
      */
     public String getCurrentHierPath() throws IOException {
         char[] path = getRawCurrentHierPath();
         return (path == null) ? null : decode(path);
     }
 
 
     /**
      * Get the level above the this hierarchy level.
      *
      * @return the raw above hierarchy level
      * @exception IOException
      */
     public char[] getRawAboveHierPath() throws IOException {
         char[] path = getRawCurrentHierPath();
         return (path == null) ? null : getRawCurrentHierPath(path);
     }
 
 
     /**
      * Get the level above the this hierarchy level.
      *
      * @return the raw above hierarchy level
      * @exception IOException
      */
     public String getEscapedAboveHierPath() throws IOException {
         char[] path = getRawAboveHierPath();
         return (path == null) ? null : new String(path);
     }
 
 
     /**
      * Get the level above the this hierarchy level.
      *
      * @return the above hierarchy level
      * @exception IOException
      * @see #decode
      */
     public String getAboveHierPath() throws IOException {
         char[] path = getRawAboveHierPath();
         return (path == null) ? null : decode(path);
     }
 
 
     /**
      * Get the raw-escaped path.
      * <p><blockquote><pre>
      *   path          = [ abs_path | opaque_part ]
      * </pre></blockquote><p>
      *
      * @return the raw-escaped path
      */
     public char[] getRawPath() {
         return _is_opaque_part ? _opaque : _path;
     }
 
 
     /**
      * Get the escaped path.
      * <p><blockquote><pre>
      *   path          = [ abs_path | opaque_part ]
      *   abs_path      = "/"  path_segments 
      *   opaque_part   = uric_no_slash *uric
      * </pre></blockquote><p>
      *
      * @return the escaped path string
      */
     public String getEscapedPath() {
         char[] path = getRawPath();
         return (path == null) ? null : new String(path);
     }
 
 
     /**
      * Get the path.
      * <p><blockquote><pre>
      *   path          = [ abs_path | opaque_part ]
      * </pre></blockquote><p>
      * @return the path string
      * @exception IOException
      * @see #decode
      */
     public String getPath() throws IOException { 
         char[] path =  getRawPath();
         return (path == null) ? null : decode(path);
     }
 
 
     /**
      * Get the raw-escaped basename of the path.
      *
      * @return the raw-escaped basename
      */
     public char[] getRawName() {
         if (_path == null) return null;
 
         int at = 0;
         for (int i = _path.length - 1; i >= 0; i--) {
             if (_path[i] == '/') {
                 at = i + 1;
                 break;
             }
         }
         int len = _path.length - at;
         char[] basename =  new char[len];
         System.arraycopy(_path, at, basename, 0, len);
         return basename;
     }
 
 
     /**
      * Get the escaped basename of the path.
      *
      * @return the escaped basename string
      */
     public String getEscapedName() {
         char[] basename = getRawName();
         return (basename == null) ? null : new String(basename);
     }
 
 
     /**
      * Get the basename of the path.
      *
      * @return the basename string
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @see #decode
      */
     public String getName() throws IOException {
         char[] basename = getRawName();
         return (basename == null) ? null : decode(getRawName());
     }
 
     // ----------------------------------------------------- The path and query 
 
     /**
      * Get the raw-escaped path and query.
      *
      * @return the raw-escaped path and query
      */
     public char[] getRawPathQuery() {
 
         if (_path == null && _query == null) {
             return null;
         }
         StringBuffer buff = new StringBuffer();
         if (_path != null) {
             buff.append(_path);
         }
         if (_query != null) {
             buff.append('?');
             buff.append(_query);
         }
         return buff.toString().toCharArray();
     }
 
 
     /**
      * Get the escaped query.
      *
      * @return the escaped path and query string
      */
     public String getEscapedPathQuery() {
         char[] rawPathQuery = getRawPathQuery();
         return (rawPathQuery == null) ? null : new String(rawPathQuery);
     }
 
 
     /**
      * Get the path and query.
      *
      * @return the path and query string.
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @see #decode
      */
     public String getPathQuery() throws IOException {
         char[] rawPathQuery = getRawPathQuery();
         return (rawPathQuery == null) ? null : decode(rawPathQuery);
     }
 
     // -------------------------------------------------------------- The query 
 
     /**
      * Set the raw-escaped query.
      *
      * @param escapedQuery the raw-escaped query
      * @exception IOException escaped query not valid
      * @throws NullPointerException null query
      */
     public void setRawQuery(char[] escapedQuery) throws IOException {
         if (!validate(escapedQuery, query))
             throw new IOException(/*IOException.ESCAPING,*/
                     "URI: escaped query not valid");
         _query = escapedQuery;
         setUriReference();
     }
 
 
     /**
      * Set the escaped query string.
      *
      * @param escapedQuery the escaped query string
      * @exception IOException escaped query not valid
      * @throws NullPointerException null query
      */
     public void setEscapedQuery(String escapedQuery) throws IOException {
         setRawQuery(escapedQuery.toCharArray());
     }
 
 
     /**
      * Set the query.
      * When a query string is not misunderstood the reserved special characters
      * ("&amp;", "=", "+", ",", and "$") within a query component, it is
      * recommended to use in encoding the whole query with this method.
      *
      * @param query the query string.
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @throws NullPointerException null query
      * @see #encode
      */
     public void setQuery(String query) throws IOException {
         setRawQuery(encode(query, allowed_query));
     }
 
 
     /**
      * Get the raw-escaped query.
      *
      * @return the raw-escaped query
      */
     public char[] getRawQuery() {
         return _query;
     }
 
 
     /**
      * Get the escaped query.
      *
      * @return the escaped query string
      */
     public String getEscapedQuery() {
         return (_query == null) ? null : new String(_query);
     }
 
 
     /**
      * Get the query.
      *
      * @return the query string.
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @see #decode
      */
     public String getQuery() throws IOException {
         return (_query == null) ? null : decode(_query);
     }
 
     // ----------------------------------------------------------- The fragment 
 
     /**
      * Set the raw-escaped fragment.
      *
      * @param escapedFragment the raw-escaped fragment
      * @exception IOException escaped fragment not valid
      * @throws NullPointerException null fragment
      */
     public void setRawFragment(char[] escapedFragment) throws IOException {
         if (!validate(escapedFragment, fragment))
             throw new IOException(/*IOException.ESCAPING,*/
                     "URI: escaped fragment not valid");
         _fragment = escapedFragment;
         setUriReference();
     }
 
 
     /**
      * Set the escaped fragment string.
      *
      * @param escapedFragment the escaped fragment string
      * @exception IOException escaped fragment not valid
      * @throws NullPointerException null fragment
      */
     public void setEscapedFragment(String escapedFragment) throws IOException {
         char[] fragmentSequence = escapedFragment.toCharArray();
         if (!validate(fragmentSequence, fragment))
             throw new IOException(/*IOException.ESCAPING,*/
                     "URI: escaped fragment not valid");
         _fragment = fragmentSequence;
         setUriReference();
     }
 
 
     /**
      * Set the fragment.
      *
      * @param the fragment string.
      * @exception IOException
      * Or unsupported character encoding
      * @throws NullPointerException null fragment
      */
     public void setFragment(String fragment) throws IOException {
         _fragment = encode(fragment, allowed_fragment);
         setUriReference();
     }
 
 
     /**
      * Get the raw-escaped fragment.
      * <p>
      * The optional fragment identifier is not part of a URI, but is often used
      * in conjunction with a URI.
      * <p>
      * The format and interpretation of fragment identifiers is dependent on
      * the media type [RFC2046] of the retrieval result.
      * <p>
      * A fragment identifier is only meaningful when a URI reference is
      * intended for retrieval and the result of that retrieval is a document
      * for which the identified fragment is consistently defined.
      *
      * @return the raw-escaped fragment
      */
     public char[] getRawFragment() {
         return _fragment;
     }
 
 
     /**
      * Get the escaped fragment.
      *
      * @return the escaped fragment string
      */
     public String getEscapedFragment() {
         return (_fragment == null) ? null : new String(_fragment);
     }
 
 
     /**
      * Get the fragment.
      *
      * @return the fragment string
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @see #decode
      */
     public String getFragment() throws IOException {
         return (_fragment == null) ? null : decode(_fragment);
     }
 
     // ------------------------------------------------------------- Utilities 
 
     /**
      * Normalize the given hier path part.
      *
      * @param path the path to normalize
      * @return the normalized path
      */
     protected char[] normalize(char[] path) {
 
         if (path == null) return null;
 
         String normalized = new String(path);
         boolean endsWithSlash = true;
         // precondition
         if (!normalized.endsWith("/")) {
             normalized += '/';
             endsWithSlash = false;
         }
         if (normalized.endsWith("/./") || normalized.endsWith("/../")) {
             endsWithSlash = true;
         }
         // Resolve occurrences of "/./" in the normalized path
         while (true) {
             int at = normalized.indexOf("/./");
             if (at == -1) {
                 break;
             }
             normalized = normalized.substring(0, at) +
             normalized.substring(at + 2);
         }
         // Resolve occurrences of "/../" in the normalized path
         while (true) {
             int at = normalized.indexOf("/../");
             if (at == -1) {
                 break;
             }
             if (at == 0) {
                 normalized = "/";
                 break;
             }
             int backward = normalized.lastIndexOf('/', at - 1);
             if (backward == -1) {
                 // consider the rel_path
                 normalized = normalized.substring(at + 4);
             } else {
                 normalized = normalized.substring(0, backward) +
                 normalized.substring(at + 3);
             }
         }
         // Resolve occurrences of "//" in the normalized path
         while (true) {
             int at = normalized.indexOf("//");
             if (at == -1) {
                 break;
             }
             normalized = normalized.substring(0, at) +
             normalized.substring(at + 1);
         }
         if (!endsWithSlash && normalized.endsWith("/")) {
             normalized = normalized.substring(0, normalized.length()-1);
         } else if (endsWithSlash && !normalized.endsWith("/")) {
             normalized = normalized + "/";
         }
         // Set the normalized path that we have completed
         return normalized.toCharArray();
     }
 
 
     /**
      * Normalize the path part of this URI.
      */
     public void normalize() {
         _path = normalize(_path);
     }
 
 
     /**
      * Test if the first array is equal to the second array.
      *
      * @param first the first character array
      * @param second the second character array
      * @return true if they're equal
      */
     protected boolean equals(char[] first, char[] second) {
 
         if (first == null && second == null) {
             return true;
         }
         if (first == null || second == null) {
             return false;
         }
         if (first.length != second.length) {
             return false;
         }
         for (int i = 0; i < first.length; i++) {
             if (first[i] != second[i]) {
                 return false;
             }
         }
         return true;
     }
 
 
     /**
      * Test an object if this URI is equal to another.
      *
      * @param obj an object to compare
      * @return true if two URI objects are equal
      */
     public boolean equals(Object obj) {
 
         // normalize and test each components
         if (obj == this) {
             return true;
         }
         if (!(obj instanceof URI)) {
             return false;
         }
         URI another = (URI) obj;
         // scheme
         if (!equals(_scheme, another._scheme)) {
             return false;
         }
         // is_opaque_part or is_hier_part?  and opaque
         if (!equals(_opaque, another._opaque)) {
             return false;
         }
         // is_hier_part
         // has_authority
         if (!equals(_authority, another._authority)) {
             return false;
         }
         // path
         if (!equals(_path, another._path)) {
             return false;
         }
         // has_query
         if (!equals(_query, another._query)) {
             return false;
         }
         // has_fragment?  should be careful of the only fragment case.
         if (!equals(_fragment, another._fragment)) {
             return false;
         }
         return true;
     }
 
     // ---------------------------------------------------------- Serialization
 
     /**
      * Write the content of this URI.
      *
      * @param oos the object-output stream
      */
     protected void writeObject(java.io.ObjectOutputStream oos)
         throws IOException {
 
         oos.defaultWriteObject();
     }
 
 
     /**
      * Read a URI.
      *
      * @param ois the object-input stream
      */
     protected void readObject(java.io.ObjectInputStream ois)
         throws ClassNotFoundException, IOException {
 
         ois.defaultReadObject();
     }
 
     // ------------------------------------------------------------- Comparison 
 
     /**
      * Compare this URI to another object. 
      *
      * @param obj the object to be compared.
      * @return 0, if it's same,
      * -1, if failed, first being compared with in the authority component
      * @exception ClassCastException not URI argument
      * @throws NullPointerException null object
      */
     public int compareTo(Object obj) {
 
         URI another = (URI) obj;
         if (!equals(_authority, another.getRawAuthority())) return -1;
         return toString().compareTo(another.toString());
     }
 
     // ------------------------------------------------------------------ Clone
 
     /**
      * Create and return a copy of this object, the URI-reference containing
      * the userinfo component.  Notice that the whole URI-reference including
      * the userinfo component counld not be gotten as a <code>String</code>.
      * <p>
      * To copy the identical <code>URI</code> object including the userinfo
      * component, it should be used.
      *
      * @return a clone of this instance
      */
     public synchronized Object clone() {
 
         URI instance = new URI();
 
         instance._uri = _uri;
         instance._scheme = _scheme;
         instance._opaque = _opaque;
         instance._authority = _authority;
         instance._userinfo = _userinfo;
         instance._host = _host;
         instance._port = _port;
         instance._path = _path;
         instance._query = _query;
         instance._fragment = _fragment;
         // flags
         instance._is_hier_part = _is_hier_part;
         instance._is_opaque_part = _is_opaque_part;
         instance._is_net_path = _is_net_path;
         instance._is_abs_path = _is_abs_path;
         instance._is_rel_path = _is_rel_path;
         instance._is_reg_name = _is_reg_name;
         instance._is_server = _is_server;
         instance._is_hostname = _is_hostname;
         instance._is_IPv4address = _is_IPv4address;
         instance._is_IPv6reference = _is_IPv6reference;
 
         return instance;
     }
 
     // ------------------------------------------------------------ Get the URI
 
     /**
      * It can be gotten the URI character sequence. It's raw-escaped.
      * For the purpose of the protocol to be transported, it will be useful.
      * <p>
      * It is clearly unwise to use a URL that contains a password which is
      * intended to be secret. In particular, the use of a password within
      * the 'userinfo' component of a URL is strongly disrecommended except
      * in those rare cases where the 'password' parameter is intended to be
      * public.
      * <p>
      * When you want to get each part of the userinfo, you need to use the
      * specific methods in the specific URL. It depends on the specific URL.
      *
      * @return URI character sequence
      */
     public char[] getRawURI() {
         return _uri;
     }
 
 
     /**
      * It can be gotten the URI character sequence. It's escaped.
      * For the purpose of the protocol to be transported, it will be useful.
      *
      * @return the URI string
      */
     public String getEscapedURI() {
         return (_uri == null) ? null : new String(_uri);
     }
     
 
     /**
      * It can be gotten the URI character sequence.
      *
      * @return the URI string
      * @exception IOException incomplete trailing escape pattern
      * Or unsupported character encoding
      * @see #decode
      */
     public String getURI() throws IOException {
         return (_uri == null) ? null : decode(_uri);
     }
 
 
     /**
      * Get the escaped URI string.
      * <p>
      * On the document, the URI-reference form is only used without the userinfo
      * component like http://jakarta.apache.org/ by the security reason.
      * But the URI-reference form with the userinfo component could be parsed.
      * <p>
      * In other words, this URI and any its subclasses must not expose the
      * URI-reference expression with the userinfo component like
      * http://user:password@hostport/restricted_zone.<br>
      * It means that the API client programmer should extract each user and
      * password to access manually.  Probably it will be supported in the each
      * subclass, however, not a whole URI-reference expression.
      *
      * @return the URI string
      * @see #clone()
      */
     public String toString() {
         return getEscapedURI();
     }
 
 
     // ------------------------------------------------------------ Inner class
 
     /** 
      * A mapping to determine the (somewhat arbitrarily) preferred charset for 
      * a given locale.  Supports all locales recognized in JDK 1.1.
      * <p>
      * The distribution of this class is Servlets.com.    It was originally
      * written by Jason Hunter [jhunter at acm.org] and used by with permission.
      */
     public static class LocaleToCharsetMap {
 
         private static Hashtable map;
         static {
             map = new Hashtable();
             map.put("ar", "ISO-8859-6");
             map.put("be", "ISO-8859-5");
             map.put("bg", "ISO-8859-5");
             map.put("ca", "ISO-8859-1");
             map.put("cs", "ISO-8859-2");
             map.put("da", "ISO-8859-1");
             map.put("de", "ISO-8859-1");
             map.put("el", "ISO-8859-7");
             map.put("en", "ISO-8859-1");
             map.put("es", "ISO-8859-1");
             map.put("et", "ISO-8859-1");
             map.put("fi", "ISO-8859-1");
             map.put("fr", "ISO-8859-1");
             map.put("hr", "ISO-8859-2");
             map.put("hu", "ISO-8859-2");
             map.put("is", "ISO-8859-1");
             map.put("it", "ISO-8859-1");
             map.put("iw", "ISO-8859-8");
             map.put("ja", "Shift_JIS");
             map.put("ko", "EUC-KR");
             map.put("lt", "ISO-8859-2");
             map.put("lv", "ISO-8859-2");
             map.put("mk", "ISO-8859-5");
             map.put("nl", "ISO-8859-1");
             map.put("no", "ISO-8859-1");
             map.put("pl", "ISO-8859-2");
             map.put("pt", "ISO-8859-1");
             map.put("ro", "ISO-8859-2");
             map.put("ru", "ISO-8859-5");
             map.put("sh", "ISO-8859-5");
             map.put("sk", "ISO-8859-2");
             map.put("sl", "ISO-8859-2");
             map.put("sq", "ISO-8859-2");
             map.put("sr", "ISO-8859-5");
             map.put("sv", "ISO-8859-1");
             map.put("tr", "ISO-8859-9");
             map.put("uk", "ISO-8859-5");
             map.put("zh", "GB2312");
             map.put("zh_TW", "Big5");
         }
        
         /**
          * Get the preferred charset for the given locale.
          *
          * @param locale the locale
          * @return the preferred charset
          * or null if the locale is not recognized
          */
         public static String getCharset(Locale locale) {
             // try for an full name match (may include country)
             String charset = (String) map.get(locale.toString());
             if (charset != null) return charset;
            
             // if a full name didn't match, try just the language
             charset = (String) map.get(locale.getLanguage());
             return charset;  // may be null
         }
 
     }
 
 }
 