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 }