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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2006, 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.IOException; | |
| 29 | +import java.io.OutputStream; | |
| 30 | + | |
| 31 | +/** | |
| 32 | + * An implementation of <code>ImageOutputStream</code> that writes its | |
| 33 | + * output to a regular <code>OutputStream</code>. A memory buffer is | |
| 34 | + * used to cache at least the data between the discard position and | |
| 35 | + * the current write position. The only constructor takes an | |
| 36 | + * <code>OutputStream</code>, so this class may not be used for | |
| 37 | + * read/modify/write operations. Reading can occur only on parts of | |
| 38 | + * the stream that have already been written to the cache and not | |
| 39 | + * yet flushed. | |
| 40 | + * | |
| 41 | + */ | |
| 42 | +public class MemoryCacheImageOutputStream extends ImageOutputStreamImpl { | |
| 43 | + | |
| 44 | + private OutputStream stream; | |
| 45 | + | |
| 46 | + private MemoryCache cache = new MemoryCache(); | |
| 47 | + | |
| 48 | + /** | |
| 49 | + * Constructs a <code>MemoryCacheImageOutputStream</code> that will write | |
| 50 | + * to a given <code>OutputStream</code>. | |
| 51 | + * | |
| 52 | + * @param stream an <code>OutputStream</code> to write to. | |
| 53 | + * | |
| 54 | + * @exception IllegalArgumentException if <code>stream</code> is | |
| 55 | + * <code>null</code>. | |
| 56 | + */ | |
| 57 | + public MemoryCacheImageOutputStream(OutputStream stream) { | |
| 58 | + if (stream == null) { | |
| 59 | + throw new IllegalArgumentException("stream == null!"); | |
| 60 | + } | |
| 61 | + this.stream = stream; | |
| 62 | + } | |
| 63 | + | |
| 64 | + public int read() throws IOException { | |
| 65 | + checkClosed(); | |
| 66 | + | |
| 67 | + bitOffset = 0; | |
| 68 | + | |
| 69 | + int val = cache.read(streamPos); | |
| 70 | + if (val != -1) { | |
| 71 | + ++streamPos; | |
| 72 | + } | |
| 73 | + return val; | |
| 74 | + } | |
| 75 | + | |
| 76 | + public int read(byte[] b, int off, int len) throws IOException { | |
| 77 | + checkClosed(); | |
| 78 | + | |
| 79 | + if (b == null) { | |
| 80 | + throw new NullPointerException("b == null!"); | |
| 81 | + } | |
| 82 | + // Fix 4467608: read([B,I,I) works incorrectly if len<=0 | |
| 83 | + if (off < 0 || len < 0 || off + len > b.length || off + len < 0) { | |
| 84 | + throw new IndexOutOfBoundsException | |
| 85 | + ("off < 0 || len < 0 || off+len > b.length || off+len < 0!"); | |
| 86 | + } | |
| 87 | + | |
| 88 | + bitOffset = 0; | |
| 89 | + | |
| 90 | + if (len == 0) { | |
| 91 | + return 0; | |
| 92 | + } | |
| 93 | + | |
| 94 | + // check if we're already at/past EOF i.e. | |
| 95 | + // no more bytes left to read from cache | |
| 96 | + long bytesLeftInCache = cache.getLength() - streamPos; | |
| 97 | + if (bytesLeftInCache <= 0) { | |
| 98 | + return -1; // EOF | |
| 99 | + } | |
| 100 | + | |
| 101 | + // guaranteed by now that bytesLeftInCache > 0 && len > 0 | |
| 102 | + // and so the rest of the error checking is done by cache.read() | |
| 103 | + // NOTE that alot of error checking is duplicated | |
| 104 | + len = (int)Math.min(bytesLeftInCache, (long)len); | |
| 105 | + cache.read(b, off, len, streamPos); | |
| 106 | + streamPos += len; | |
| 107 | + return len; | |
| 108 | + } | |
| 109 | + | |
| 110 | + public void write(int b) throws IOException { | |
| 111 | + flushBits(); // this will call checkClosed() for us | |
| 112 | + cache.write(b, streamPos); | |
| 113 | + ++streamPos; | |
| 114 | + } | |
| 115 | + | |
| 116 | + public void write(byte[] b, int off, int len) throws IOException { | |
| 117 | + flushBits(); // this will call checkClosed() for us | |
| 118 | + cache.write(b, off, len, streamPos); | |
| 119 | + streamPos += len; | |
| 120 | + } | |
| 121 | + | |
| 122 | + public long length() { | |
| 123 | + try { | |
| 124 | + checkClosed(); | |
| 125 | + return cache.getLength(); | |
| 126 | + } catch (IOException e) { | |
| 127 | + return -1L; | |
| 128 | + } | |
| 129 | + } | |
| 130 | + | |
| 131 | + /** | |
| 132 | + * Returns <code>true</code> since this | |
| 133 | + * <code>ImageOutputStream</code> caches data in order to allow | |
| 134 | + * seeking backwards. | |
| 135 | + * | |
| 136 | + * @return <code>true</code>. | |
| 137 | + * | |
| 138 | + * @see #isCachedMemory | |
| 139 | + * @see #isCachedFile | |
| 140 | + */ | |
| 141 | + public boolean isCached() { | |
| 142 | + return true; | |
| 143 | + } | |
| 144 | + | |
| 145 | + /** | |
| 146 | + * Returns <code>false</code> since this | |
| 147 | + * <code>ImageOutputStream</code> does not maintain a file cache. | |
| 148 | + * | |
| 149 | + * @return <code>false</code>. | |
| 150 | + * | |
| 151 | + * @see #isCached | |
| 152 | + * @see #isCachedMemory | |
| 153 | + */ | |
| 154 | + public boolean isCachedFile() { | |
| 155 | + return false; | |
| 156 | + } | |
| 157 | + | |
| 158 | + /** | |
| 159 | + * Returns <code>true</code> since this | |
| 160 | + * <code>ImageOutputStream</code> maintains a main memory cache. | |
| 161 | + * | |
| 162 | + * @return <code>true</code>. | |
| 163 | + * | |
| 164 | + * @see #isCached | |
| 165 | + * @see #isCachedFile | |
| 166 | + */ | |
| 167 | + public boolean isCachedMemory() { | |
| 168 | + return true; | |
| 169 | + } | |
| 170 | + | |
| 171 | + /** | |
| 172 | + * Closes this <code>MemoryCacheImageOutputStream</code>. All | |
| 173 | + * pending data is flushed to the output, and the cache | |
| 174 | + * is released. The destination <code>OutputStream</code> | |
| 175 | + * is not closed. | |
| 176 | + */ | |
| 177 | + public void close() throws IOException { | |
| 178 | + long length = cache.getLength(); | |
| 179 | + seek(length); | |
| 180 | + flushBefore(length); | |
| 181 | + super.close(); | |
| 182 | + cache.reset(); | |
| 183 | + cache = null; | |
| 184 | + stream = null; | |
| 185 | + } | |
| 186 | + | |
| 187 | + public void flushBefore(long pos) throws IOException { | |
| 188 | + long oFlushedPos = flushedPos; | |
| 189 | + super.flushBefore(pos); // this will call checkClosed() for us | |
| 190 | + | |
| 191 | + long flushBytes = flushedPos - oFlushedPos; | |
| 192 | + cache.writeToStream(stream, oFlushedPos, flushBytes); | |
| 193 | + cache.disposeBefore(flushedPos); | |
| 194 | + stream.flush(); | |
| 195 | + } | |
| 196 | +} | |