J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | } |