View Javadoc
1   /*
2    * Copyright (c) 1998, 2009, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package sun.misc;
27  
28  import java.io.EOFException;
29  import java.net.URL;
30  import java.io.IOException;
31  import java.io.InterruptedIOException;
32  import java.io.InputStream;
33  import java.security.CodeSigner;
34  import java.util.jar.Manifest;
35  import java.nio.ByteBuffer;
36  import java.util.Arrays;
37  import sun.nio.ByteBuffered;
38  
39  /**
40   * This class is used to represent a Resource that has been loaded
41   * from the class path.
42   *
43   * @author  David Connelly
44   * @since   1.2
45   */
46  public abstract class Resource {
47      /**
48       * Returns the name of the Resource.
49       */
50      public abstract String getName();
51  
52      /**
53       * Returns the URL of the Resource.
54       */
55      public abstract URL getURL();
56  
57      /**
58       * Returns the CodeSource URL for the Resource.
59       */
60      public abstract URL getCodeSourceURL();
61  
62      /**
63       * Returns an InputStream for reading the Resource data.
64       */
65      public abstract InputStream getInputStream() throws IOException;
66  
67      /**
68       * Returns the length of the Resource data, or -1 if unknown.
69       */
70      public abstract int getContentLength() throws IOException;
71  
72      private InputStream cis;
73  
74      /* Cache result in case getBytes is called after getByteBuffer. */
75      private synchronized InputStream cachedInputStream() throws IOException {
76          if (cis == null) {
77              cis = getInputStream();
78          }
79          return cis;
80      }
81  
82      /**
83       * Returns the Resource data as an array of bytes.
84       */
85      public byte[] getBytes() throws IOException {
86          byte[] b;
87          // Get stream before content length so that a FileNotFoundException
88          // can propagate upwards without being caught too early
89          InputStream in = cachedInputStream();
90  
91          // This code has been uglified to protect against interrupts.
92          // Even if a thread has been interrupted when loading resources,
93          // the IO should not abort, so must carefully retry, failing only
94          // if the retry leads to some other IO exception.
95  
96          boolean isInterrupted = Thread.interrupted();
97          int len;
98          for (;;) {
99              try {
100                 len = getContentLength();
101                 break;
102             } catch (InterruptedIOException iioe) {
103                 Thread.interrupted();
104                 isInterrupted = true;
105             }
106         }
107 
108         try {
109             b = new byte[0];
110             if (len == -1) len = Integer.MAX_VALUE;
111             int pos = 0;
112             while (pos < len) {
113                 int bytesToRead;
114                 if (pos >= b.length) { // Only expand when there's no room
115                     bytesToRead = Math.min(len - pos, b.length + 1024);
116                     if (b.length < pos + bytesToRead) {
117                         b = Arrays.copyOf(b, pos + bytesToRead);
118                     }
119                 } else {
120                     bytesToRead = b.length - pos;
121                 }
122                 int cc = 0;
123                 try {
124                     cc = in.read(b, pos, bytesToRead);
125                 } catch (InterruptedIOException iioe) {
126                     Thread.interrupted();
127                     isInterrupted = true;
128                 }
129                 if (cc < 0) {
130                     if (len != Integer.MAX_VALUE) {
131                         throw new EOFException("Detect premature EOF");
132                     } else {
133                         if (b.length != pos) {
134                             b = Arrays.copyOf(b, pos);
135                         }
136                         break;
137                     }
138                 }
139                 pos += cc;
140             }
141         } finally {
142             try {
143                 in.close();
144             } catch (InterruptedIOException iioe) {
145                 isInterrupted = true;
146             } catch (IOException ignore) {}
147 
148             if (isInterrupted) {
149                 Thread.currentThread().interrupt();
150             }
151         }
152         return b;
153     }
154 
155     /**
156      * Returns the Resource data as a ByteBuffer, but only if the input stream
157      * was implemented on top of a ByteBuffer. Return <tt>null</tt> otherwise.
158      */
159     public ByteBuffer getByteBuffer() throws IOException {
160         InputStream in = cachedInputStream();
161         if (in instanceof ByteBuffered) {
162             return ((ByteBuffered)in).getByteBuffer();
163         }
164         return null;
165     }
166 
167     /**
168      * Returns the Manifest for the Resource, or null if none.
169      */
170     public Manifest getManifest() throws IOException {
171         return null;
172     }
173 
174     /**
175      * Returns theCertificates for the Resource, or null if none.
176      */
177     public java.security.cert.Certificate[] getCertificates() {
178         return null;
179     }
180 
181     /**
182      * Returns the code signers for the Resource, or null if none.
183      */
184     public CodeSigner[] getCodeSigners() {
185         return null;
186     }
187 }