View Javadoc

1   /*
2    * ====================================================================
3    *
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 1999 The Apache Software Foundation.  All rights 
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer. 
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution, if
22   *    any, must include the following acknowlegement:  
23   *       "This product includes software developed by the 
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowlegement may appear in the software itself,
26   *    if and wherever such third-party acknowlegements normally appear.
27   *
28   * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
29   *    Foundation" must not be used to endorse or promote products derived
30   *    from this software without prior written permission. For written 
31   *    permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache"
34   *    nor may "Apache" appear in their names without prior written
35   *    permission of the Apache Group.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   */ 
51  
52  package net.wotonomy.foundation.internal;
53  
54  import java.io.ByteArrayOutputStream;
55  import java.io.IOException;
56  import java.io.InputStream;
57  import java.net.URL;
58  import java.util.Enumeration;
59  import java.util.Hashtable;
60  import java.util.zip.ZipEntry;
61  import java.util.zip.ZipInputStream;
62  
63  /***
64   * This implementation of URL Resource Reader assumes 2 types
65   * of base urls. A base url that ends with / is considered a
66   * resource folder, whereas a resource that does not end with
67   * / is considered a zip/jar resource folder.
68   *
69   * If the resource folder happens is a zip/jar archive, the
70   * entries are always cached.
71   * For non-zip base urls, one could specify whether or not it should
72   * be cached.
73   *
74   * @author Harish Prabandham
75   */
76  public class URLResourceReader  {
77      private Hashtable resourceCache = new Hashtable();
78      private boolean iszip = true;
79      private URL url = null;
80      private boolean cache = true;
81  
82      /***
83       * Creates a new URLResourceReader object. You can either give
84       * the URL of the zip/jar file or a base url where to
85       * look for additional resources. If the url ends with
86       * "/" then it is assumed to be  a Base URL. 
87       * @param The base url to look for the resources.
88       * @param If the base url is not a zip/jar, then true indicates
89       * that entries should be cached, false otherwise.
90       */
91      public URLResourceReader(URL baseurl, boolean cache) throws IOException {
92          this.url = baseurl;
93          this.cache = cache;
94          this.iszip = !url.getFile().endsWith("/");
95          if(this.iszip)
96              this.cache = true;
97          initialize();
98      }
99  
100     /***
101      * equivalent to URLResourceReader(baseurl, false)
102      */
103     public URLResourceReader(URL baseurl) throws IOException {
104         this(baseurl, false);
105     }
106 
107     /***
108      * Creates a new URLResourceReader object with the given
109      * input stream. The stream is assumed to be a zip/jar
110      * stream.
111      */
112     public URLResourceReader(InputStream is) throws IOException {
113         init(is);
114     }
115 
116     private void initialize() throws IOException {
117         if(iszip) {
118             InputStream is = url.openStream();
119             init(is);
120             is.close();
121         }
122     }
123 
124     private byte[] readFully(InputStream is) throws IOException {
125         byte[] buf = new byte[1024];
126         int num = 0;
127         ByteArrayOutputStream bout = new ByteArrayOutputStream();
128 
129         while( (num = is.read(buf)) != -1) {
130             bout.write(buf, 0, num);
131         }
132 
133         return bout.toByteArray();
134     }
135 
136     private void init(InputStream is) throws IOException {
137         ZipInputStream zstream = new ZipInputStream(is);
138         ZipEntry entry;
139         
140         while( (entry = zstream.getNextEntry()) != null) {
141             byte[] entryData = readFully(zstream);
142             if(cache)
143                 resourceCache.put(entry.getName(), entryData);
144             zstream.closeEntry();
145         }
146         
147         zstream.close();
148     }
149 
150     /***
151      * Returns an Enumeration of all "known" resource names.
152      */
153     public Enumeration getResourceNames() {
154         return resourceCache.keys();
155     }
156 
157     /***
158      * Returns an array of bytes read for this resource if the
159      * resource exists. This method blocks until the resource
160      * has been fully read. If the resource does not exist,
161      * this method returns null.
162      */
163     public byte[] getResource(String  resource) {
164         // lookup the data in the cache...
165         byte[] data = (byte[]) resourceCache.get(resource);
166         if(data != null) {
167             return data;
168         }
169 
170         // if the data was to come from a zip file that we
171         // already read fully & cached , then it is probably
172         // not there.
173         if(iszip) {
174             return null;
175         }
176 
177         // Now the only choice left is to make a url connection.
178         try {
179             URL realURL = new URL(url.getProtocol(), url.getHost(),
180                                   url.getFile() + resource);
181             data = readFully(realURL.openStream());
182             // add it to cache if needed...
183             if(cache)
184                 resourceCache.put(resource, data);
185             return data;
186         } catch(Exception e) {
187             return null;
188         }
189     }
190 
191     public void close() {
192         resourceCache.clear();
193         resourceCache = null;
194     }
195 
196     public String toString() {
197 	return url.toString();
198     }
199 }
200 
201 
202 
203 
204 
205 
206 
207