J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2006 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 java.util.zip; |
| 27 | |
| 28 | /** |
| 29 | * This class provides support for general purpose decompression using the |
| 30 | * popular ZLIB compression library. The ZLIB compression library was |
| 31 | * initially developed as part of the PNG graphics standard and is not |
| 32 | * protected by patents. It is fully described in the specifications at |
| 33 | * the <a href="package-summary.html#package_description">java.util.zip |
| 34 | * package description</a>. |
| 35 | * |
| 36 | * <p>The following code fragment demonstrates a trivial compression |
| 37 | * and decompression of a string using <tt>Deflater</tt> and |
| 38 | * <tt>Inflater</tt>. |
| 39 | * |
| 40 | * <blockquote><pre> |
| 41 | * try { |
| 42 | * // Encode a String into bytes |
| 43 | * String inputString = "blahblahblah\u20AC\u20AC"; |
| 44 | * byte[] input = inputString.getBytes("UTF-8"); |
| 45 | * |
| 46 | * // Compress the bytes |
| 47 | * byte[] output = new byte[100]; |
| 48 | * Deflater compresser = new Deflater(); |
| 49 | * compresser.setInput(input); |
| 50 | * compresser.finish(); |
| 51 | * int compressedDataLength = compresser.deflate(output); |
| 52 | * |
| 53 | * // Decompress the bytes |
| 54 | * Inflater decompresser = new Inflater(); |
| 55 | * decompresser.setInput(output, 0, compressedDataLength); |
| 56 | * byte[] result = new byte[100]; |
| 57 | * int resultLength = decompresser.inflate(result); |
| 58 | * decompresser.end(); |
| 59 | * |
| 60 | * // Decode the bytes into a String |
| 61 | * String outputString = new String(result, 0, resultLength, "UTF-8"); |
| 62 | * } catch(java.io.UnsupportedEncodingException ex) { |
| 63 | * // handle |
| 64 | * } catch (java.util.zip.DataFormatException ex) { |
| 65 | * // handle |
| 66 | * } |
| 67 | * </pre></blockquote> |
| 68 | * |
| 69 | * @see Deflater |
| 70 | * @author David Connelly |
| 71 | * |
| 72 | */ |
| 73 | public |
| 74 | class Inflater { |
| 75 | private long strm; |
| 76 | private byte[] buf = new byte[0]; |
| 77 | private int off, len; |
| 78 | private boolean finished; |
| 79 | private boolean needDict; |
| 80 | |
| 81 | static { |
| 82 | /* Zip library is loaded from System.initializeSystemClass */ |
| 83 | initIDs(); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Creates a new decompressor. If the parameter 'nowrap' is true then |
| 88 | * the ZLIB header and checksum fields will not be used. This provides |
| 89 | * compatibility with the compression format used by both GZIP and PKZIP. |
| 90 | * <p> |
| 91 | * Note: When using the 'nowrap' option it is also necessary to provide |
| 92 | * an extra "dummy" byte as input. This is required by the ZLIB native |
| 93 | * library in order to support certain optimizations. |
| 94 | * |
| 95 | * @param nowrap if true then support GZIP compatible compression |
| 96 | */ |
| 97 | public Inflater(boolean nowrap) { |
| 98 | strm = init(nowrap); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Creates a new decompressor. |
| 103 | */ |
| 104 | public Inflater() { |
| 105 | this(false); |
| 106 | } |
| 107 | |
| 108 | /** |
| 109 | * Sets input data for decompression. Should be called whenever |
| 110 | * needsInput() returns true indicating that more input data is |
| 111 | * required. |
| 112 | * @param b the input data bytes |
| 113 | * @param off the start offset of the input data |
| 114 | * @param len the length of the input data |
| 115 | * @see Inflater#needsInput |
| 116 | */ |
| 117 | public synchronized void setInput(byte[] b, int off, int len) { |
| 118 | if (b == null) { |
| 119 | throw new NullPointerException(); |
| 120 | } |
| 121 | if (off < 0 || len < 0 || off > b.length - len) { |
| 122 | throw new ArrayIndexOutOfBoundsException(); |
| 123 | } |
| 124 | this.buf = b; |
| 125 | this.off = off; |
| 126 | this.len = len; |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * Sets input data for decompression. Should be called whenever |
| 131 | * needsInput() returns true indicating that more input data is |
| 132 | * required. |
| 133 | * @param b the input data bytes |
| 134 | * @see Inflater#needsInput |
| 135 | */ |
| 136 | public void setInput(byte[] b) { |
| 137 | setInput(b, 0, b.length); |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Sets the preset dictionary to the given array of bytes. Should be |
| 142 | * called when inflate() returns 0 and needsDictionary() returns true |
| 143 | * indicating that a preset dictionary is required. The method getAdler() |
| 144 | * can be used to get the Adler-32 value of the dictionary needed. |
| 145 | * @param b the dictionary data bytes |
| 146 | * @param off the start offset of the data |
| 147 | * @param len the length of the data |
| 148 | * @see Inflater#needsDictionary |
| 149 | * @see Inflater#getAdler |
| 150 | */ |
| 151 | public synchronized void setDictionary(byte[] b, int off, int len) { |
| 152 | if (strm == 0 || b == null) { |
| 153 | throw new NullPointerException(); |
| 154 | } |
| 155 | if (off < 0 || len < 0 || off > b.length - len) { |
| 156 | throw new ArrayIndexOutOfBoundsException(); |
| 157 | } |
| 158 | setDictionary(strm, b, off, len); |
| 159 | needDict = false; |
| 160 | } |
| 161 | |
| 162 | /** |
| 163 | * Sets the preset dictionary to the given array of bytes. Should be |
| 164 | * called when inflate() returns 0 and needsDictionary() returns true |
| 165 | * indicating that a preset dictionary is required. The method getAdler() |
| 166 | * can be used to get the Adler-32 value of the dictionary needed. |
| 167 | * @param b the dictionary data bytes |
| 168 | * @see Inflater#needsDictionary |
| 169 | * @see Inflater#getAdler |
| 170 | */ |
| 171 | public void setDictionary(byte[] b) { |
| 172 | setDictionary(b, 0, b.length); |
| 173 | } |
| 174 | |
| 175 | /** |
| 176 | * Returns the total number of bytes remaining in the input buffer. |
| 177 | * This can be used to find out what bytes still remain in the input |
| 178 | * buffer after decompression has finished. |
| 179 | * @return the total number of bytes remaining in the input buffer |
| 180 | */ |
| 181 | public synchronized int getRemaining() { |
| 182 | return len; |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * Returns true if no data remains in the input buffer. This can |
| 187 | * be used to determine if #setInput should be called in order |
| 188 | * to provide more input. |
| 189 | * @return true if no data remains in the input buffer |
| 190 | */ |
| 191 | public synchronized boolean needsInput() { |
| 192 | return len <= 0; |
| 193 | } |
| 194 | |
| 195 | /** |
| 196 | * Returns true if a preset dictionary is needed for decompression. |
| 197 | * @return true if a preset dictionary is needed for decompression |
| 198 | * @see Inflater#setDictionary |
| 199 | */ |
| 200 | public synchronized boolean needsDictionary() { |
| 201 | return needDict; |
| 202 | } |
| 203 | |
| 204 | /** |
| 205 | * Returns true if the end of the compressed data stream has been |
| 206 | * reached. |
| 207 | * @return true if the end of the compressed data stream has been |
| 208 | * reached |
| 209 | */ |
| 210 | public synchronized boolean finished() { |
| 211 | return finished; |
| 212 | } |
| 213 | |
| 214 | /** |
| 215 | * Uncompresses bytes into specified buffer. Returns actual number |
| 216 | * of bytes uncompressed. A return value of 0 indicates that |
| 217 | * needsInput() or needsDictionary() should be called in order to |
| 218 | * determine if more input data or a preset dictionary is required. |
| 219 | * In the latter case, getAdler() can be used to get the Adler-32 |
| 220 | * value of the dictionary required. |
| 221 | * @param b the buffer for the uncompressed data |
| 222 | * @param off the start offset of the data |
| 223 | * @param len the maximum number of uncompressed bytes |
| 224 | * @return the actual number of uncompressed bytes |
| 225 | * @exception DataFormatException if the compressed data format is invalid |
| 226 | * @see Inflater#needsInput |
| 227 | * @see Inflater#needsDictionary |
| 228 | */ |
| 229 | public synchronized int inflate(byte[] b, int off, int len) |
| 230 | throws DataFormatException |
| 231 | { |
| 232 | if (b == null) { |
| 233 | throw new NullPointerException(); |
| 234 | } |
| 235 | if (off < 0 || len < 0 || off > b.length - len) { |
| 236 | throw new ArrayIndexOutOfBoundsException(); |
| 237 | } |
| 238 | return inflateBytes(b, off, len); |
| 239 | } |
| 240 | |
| 241 | /** |
| 242 | * Uncompresses bytes into specified buffer. Returns actual number |
| 243 | * of bytes uncompressed. A return value of 0 indicates that |
| 244 | * needsInput() or needsDictionary() should be called in order to |
| 245 | * determine if more input data or a preset dictionary is required. |
| 246 | * In the latter case, getAdler() can be used to get the Adler-32 |
| 247 | * value of the dictionary required. |
| 248 | * @param b the buffer for the uncompressed data |
| 249 | * @return the actual number of uncompressed bytes |
| 250 | * @exception DataFormatException if the compressed data format is invalid |
| 251 | * @see Inflater#needsInput |
| 252 | * @see Inflater#needsDictionary |
| 253 | */ |
| 254 | public int inflate(byte[] b) throws DataFormatException { |
| 255 | return inflate(b, 0, b.length); |
| 256 | } |
| 257 | |
| 258 | /** |
| 259 | * Returns the ADLER-32 value of the uncompressed data. |
| 260 | * @return the ADLER-32 value of the uncompressed data |
| 261 | */ |
| 262 | public synchronized int getAdler() { |
| 263 | ensureOpen(); |
| 264 | return getAdler(strm); |
| 265 | } |
| 266 | |
| 267 | /** |
| 268 | * Returns the total number of compressed bytes input so far. |
| 269 | * |
| 270 | * <p>Since the number of bytes may be greater than |
| 271 | * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now |
| 272 | * the preferred means of obtaining this information.</p> |
| 273 | * |
| 274 | * @return the total number of compressed bytes input so far |
| 275 | */ |
| 276 | public int getTotalIn() { |
| 277 | return (int) getBytesRead(); |
| 278 | } |
| 279 | |
| 280 | /** |
| 281 | * Returns the total number of compressed bytes input so far.</p> |
| 282 | * |
| 283 | * @return the total (non-negative) number of compressed bytes input so far |
| 284 | * @since 1.5 |
| 285 | */ |
| 286 | public synchronized long getBytesRead() { |
| 287 | ensureOpen(); |
| 288 | return getBytesRead(strm); |
| 289 | } |
| 290 | |
| 291 | /** |
| 292 | * Returns the total number of uncompressed bytes output so far. |
| 293 | * |
| 294 | * <p>Since the number of bytes may be greater than |
| 295 | * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now |
| 296 | * the preferred means of obtaining this information.</p> |
| 297 | * |
| 298 | * @return the total number of uncompressed bytes output so far |
| 299 | */ |
| 300 | public int getTotalOut() { |
| 301 | return (int) getBytesWritten(); |
| 302 | } |
| 303 | |
| 304 | /** |
| 305 | * Returns the total number of uncompressed bytes output so far.</p> |
| 306 | * |
| 307 | * @return the total (non-negative) number of uncompressed bytes output so far |
| 308 | * @since 1.5 |
| 309 | */ |
| 310 | public synchronized long getBytesWritten() { |
| 311 | ensureOpen(); |
| 312 | return getBytesWritten(strm); |
| 313 | } |
| 314 | |
| 315 | /** |
| 316 | * Resets inflater so that a new set of input data can be processed. |
| 317 | */ |
| 318 | public synchronized void reset() { |
| 319 | ensureOpen(); |
| 320 | reset(strm); |
| 321 | finished = false; |
| 322 | needDict = false; |
| 323 | off = len = 0; |
| 324 | } |
| 325 | |
| 326 | /** |
| 327 | * Closes the decompressor and discards any unprocessed input. |
| 328 | * This method should be called when the decompressor is no longer |
| 329 | * being used, but will also be called automatically by the finalize() |
| 330 | * method. Once this method is called, the behavior of the Inflater |
| 331 | * object is undefined. |
| 332 | */ |
| 333 | public synchronized void end() { |
| 334 | if (strm != 0) { |
| 335 | end(strm); |
| 336 | strm = 0; |
| 337 | buf = null; |
| 338 | } |
| 339 | } |
| 340 | |
| 341 | /** |
| 342 | * Closes the decompressor when garbage is collected. |
| 343 | */ |
| 344 | protected void finalize() { |
| 345 | end(); |
| 346 | } |
| 347 | |
| 348 | private void ensureOpen () { |
| 349 | if (strm == 0) |
| 350 | throw new NullPointerException(); |
| 351 | } |
| 352 | |
| 353 | private native static void initIDs(); |
| 354 | private native static long init(boolean nowrap); |
| 355 | private native static void setDictionary(long strm, byte[] b, int off, |
| 356 | int len); |
| 357 | private native int inflateBytes(byte[] b, int off, int len) |
| 358 | throws DataFormatException; |
| 359 | private native static int getAdler(long strm); |
| 360 | private native static long getBytesRead(long strm); |
| 361 | private native static long getBytesWritten(long strm); |
| 362 | private native static void reset(long strm); |
| 363 | private native static void end(long strm); |
| 364 | } |