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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2007, 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 javax.imageio.stream; | |
| 27 | + | |
| 28 | +import java.io.InputStream; | |
| 29 | +import java.io.IOException; | |
| 30 | +import com.sun.imageio.stream.StreamFinalizer; | |
| 31 | +import sun.java2d.Disposer; | |
| 32 | +import sun.java2d.DisposerRecord; | |
| 33 | + | |
| 34 | +/** | |
| 35 | + * An implementation of <code>ImageInputStream</code> that gets its | |
| 36 | + * input from a regular <code>InputStream</code>. A memory buffer is | |
| 37 | + * used to cache at least the data between the discard position and | |
| 38 | + * the current read position. | |
| 39 | + * | |
| 40 | + * <p> In general, it is preferable to use a | |
| 41 | + * <code>FileCacheImageInputStream</code> when reading from a regular | |
| 42 | + * <code>InputStream</code>. This class is provided for cases where | |
| 43 | + * it is not possible to create a writable temporary file. | |
| 44 | + * | |
| 45 | + */ | |
| 46 | +public class MemoryCacheImageInputStream extends ImageInputStreamImpl { | |
| 47 | + | |
| 48 | + private InputStream stream; | |
| 49 | + | |
| 50 | + private MemoryCache cache = new MemoryCache(); | |
| 51 | + | |
| 52 | + /** The referent to be registered with the Disposer. */ | |
| 53 | + private final Object disposerReferent; | |
| 54 | + | |
| 55 | + /** The DisposerRecord that resets the underlying MemoryCache. */ | |
| 56 | + private final DisposerRecord disposerRecord; | |
| 57 | + | |
| 58 | + /** | |
| 59 | + * Constructs a <code>MemoryCacheImageInputStream</code> that will read | |
| 60 | + * from a given <code>InputStream</code>. | |
| 61 | + * | |
| 62 | + * @param stream an <code>InputStream</code> to read from. | |
| 63 | + * | |
| 64 | + * @exception IllegalArgumentException if <code>stream</code> is | |
| 65 | + * <code>null</code>. | |
| 66 | + */ | |
| 67 | + public MemoryCacheImageInputStream(InputStream stream) { | |
| 68 | + if (stream == null) { | |
| 69 | + throw new IllegalArgumentException("stream == null!"); | |
| 70 | + } | |
| 71 | + this.stream = stream; | |
| 72 | + | |
| 73 | + disposerRecord = new StreamDisposerRecord(cache); | |
| 74 | + if (getClass() == MemoryCacheImageInputStream.class) { | |
| 75 | + disposerReferent = new Object(); | |
| 76 | + Disposer.addRecord(disposerReferent, disposerRecord); | |
| 77 | + } else { | |
| 78 | + disposerReferent = new StreamFinalizer(this); | |
| 79 | + } | |
| 80 | + } | |
| 81 | + | |
| 82 | + public int read() throws IOException { | |
| 83 | + checkClosed(); | |
| 84 | + bitOffset = 0; | |
| 85 | + long pos = cache.loadFromStream(stream, streamPos+1); | |
| 86 | + if (pos >= streamPos+1) { | |
| 87 | + return cache.read(streamPos++); | |
| 88 | + } else { | |
| 89 | + return -1; | |
| 90 | + } | |
| 91 | + } | |
| 92 | + | |
| 93 | + public int read(byte[] b, int off, int len) throws IOException { | |
| 94 | + checkClosed(); | |
| 95 | + | |
| 96 | + if (b == null) { | |
| 97 | + throw new NullPointerException("b == null!"); | |
| 98 | + } | |
| 99 | + if (off < 0 || len < 0 || off + len > b.length || off + len < 0) { | |
| 100 | + throw new IndexOutOfBoundsException | |
| 101 | + ("off < 0 || len < 0 || off+len > b.length || off+len < 0!"); | |
| 102 | + } | |
| 103 | + | |
| 104 | + bitOffset = 0; | |
| 105 | + | |
| 106 | + if (len == 0) { | |
| 107 | + return 0; | |
| 108 | + } | |
| 109 | + | |
| 110 | + long pos = cache.loadFromStream(stream, streamPos+len); | |
| 111 | + | |
| 112 | + len = (int)(pos - streamPos); // In case stream ended early | |
| 113 | + | |
| 114 | + if (len > 0) { | |
| 115 | + cache.read(b, off, len, streamPos); | |
| 116 | + streamPos += len; | |
| 117 | + return len; | |
| 118 | + } else { | |
| 119 | + return -1; | |
| 120 | + } | |
| 121 | + } | |
| 122 | + | |
| 123 | + public void flushBefore(long pos) throws IOException { | |
| 124 | + super.flushBefore(pos); // this will call checkClosed() for us | |
| 125 | + cache.disposeBefore(pos); | |
| 126 | + } | |
| 127 | + | |
| 128 | + /** | |
| 129 | + * Returns <code>true</code> since this | |
| 130 | + * <code>ImageInputStream</code> caches data in order to allow | |
| 131 | + * seeking backwards. | |
| 132 | + * | |
| 133 | + * @return <code>true</code>. | |
| 134 | + * | |
| 135 | + * @see #isCachedMemory | |
| 136 | + * @see #isCachedFile | |
| 137 | + */ | |
| 138 | + public boolean isCached() { | |
| 139 | + return true; | |
| 140 | + } | |
| 141 | + | |
| 142 | + /** | |
| 143 | + * Returns <code>false</code> since this | |
| 144 | + * <code>ImageInputStream</code> does not maintain a file cache. | |
| 145 | + * | |
| 146 | + * @return <code>false</code>. | |
| 147 | + * | |
| 148 | + * @see #isCached | |
| 149 | + * @see #isCachedMemory | |
| 150 | + */ | |
| 151 | + public boolean isCachedFile() { | |
| 152 | + return false; | |
| 153 | + } | |
| 154 | + | |
| 155 | + /** | |
| 156 | + * Returns <code>true</code> since this | |
| 157 | + * <code>ImageInputStream</code> maintains a main memory cache. | |
| 158 | + * | |
| 159 | + * @return <code>true</code>. | |
| 160 | + * | |
| 161 | + * @see #isCached | |
| 162 | + * @see #isCachedFile | |
| 163 | + */ | |
| 164 | + public boolean isCachedMemory() { | |
| 165 | + return true; | |
| 166 | + } | |
| 167 | + | |
| 168 | + /** | |
| 169 | + * Closes this <code>MemoryCacheImageInputStream</code>, freeing | |
| 170 | + * the cache. The source <code>InputStream</code> is not closed. | |
| 171 | + */ | |
| 172 | + public void close() throws IOException { | |
| 173 | + super.close(); | |
| 174 | + disposerRecord.dispose(); // this resets the MemoryCache | |
| 175 | + stream = null; | |
| 176 | + cache = null; | |
| 177 | + } | |
| 178 | + | |
| 179 | + /** | |
| 180 | + * {@inheritDoc} | |
| 181 | + */ | |
| 182 | + protected void finalize() throws Throwable { | |
| 183 | + // Empty finalizer: for performance reasons we instead use the | |
| 184 | + // Disposer mechanism for ensuring that the underlying | |
| 185 | + // MemoryCache is reset prior to garbage collection | |
| 186 | + } | |
| 187 | + | |
| 188 | + private static class StreamDisposerRecord implements DisposerRecord { | |
| 189 | + private MemoryCache cache; | |
| 190 | + | |
| 191 | + public StreamDisposerRecord(MemoryCache cache) { | |
| 192 | + this.cache = cache; | |
| 193 | + } | |
| 194 | + | |
| 195 | + public synchronized void dispose() { | |
| 196 | + if (cache != null) { | |
| 197 | + cache.reset(); | |
| 198 | + cache = null; | |
| 199 | + } | |
| 200 | + } | |
| 201 | + } | |
| 202 | +} | |