001 /*
002 * Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.util.zip;
027
028 /**
029 * This class provides support for general purpose compression using the
030 * popular ZLIB compression library. The ZLIB compression library was
031 * initially developed as part of the PNG graphics standard and is not
032 * protected by patents. It is fully described in the specifications at
033 * the <a href="package-summary.html#package_description">java.util.zip
034 * package description</a>.
035 *
036 * <p>The following code fragment demonstrates a trivial compression
037 * and decompression of a string using <tt>Deflater</tt> and
038 * <tt>Inflater</tt>.
039 *
040 * <blockquote><pre>
041 * try {
042 * // Encode a String into bytes
043 * String inputString = "blahblahblah\u20AC\u20AC";
044 * byte[] input = inputString.getBytes("UTF-8");
045 *
046 * // Compress the bytes
047 * byte[] output = new byte[100];
048 * Deflater compresser = new Deflater();
049 * compresser.setInput(input);
050 * compresser.finish();
051 * int compressedDataLength = compresser.deflate(output);
052 *
053 * // Decompress the bytes
054 * Inflater decompresser = new Inflater();
055 * decompresser.setInput(output, 0, compressedDataLength);
056 * byte[] result = new byte[100];
057 * int resultLength = decompresser.inflate(result);
058 * decompresser.end();
059 *
060 * // Decode the bytes into a String
061 * String outputString = new String(result, 0, resultLength, "UTF-8");
062 * } catch(java.io.UnsupportedEncodingException ex) {
063 * // handle
064 * } catch (java.util.zip.DataFormatException ex) {
065 * // handle
066 * }
067 * </pre></blockquote>
068 *
069 * @see Inflater
070 * @version 1.51, 05/05/07
071 * @author David Connelly
072 */
073 public class Deflater {
074 private long strm;
075 private byte[] buf = new byte[0];
076 private int off, len;
077 private int level, strategy;
078 private boolean setParams;
079 private boolean finish, finished;
080
081 /**
082 * Compression method for the deflate algorithm (the only one currently
083 * supported).
084 */
085 public static final int DEFLATED = 8;
086
087 /**
088 * Compression level for no compression.
089 */
090 public static final int NO_COMPRESSION = 0;
091
092 /**
093 * Compression level for fastest compression.
094 */
095 public static final int BEST_SPEED = 1;
096
097 /**
098 * Compression level for best compression.
099 */
100 public static final int BEST_COMPRESSION = 9;
101
102 /**
103 * Default compression level.
104 */
105 public static final int DEFAULT_COMPRESSION = -1;
106
107 /**
108 * Compression strategy best used for data consisting mostly of small
109 * values with a somewhat random distribution. Forces more Huffman coding
110 * and less string matching.
111 */
112 public static final int FILTERED = 1;
113
114 /**
115 * Compression strategy for Huffman coding only.
116 */
117 public static final int HUFFMAN_ONLY = 2;
118
119 /**
120 * Default compression strategy.
121 */
122 public static final int DEFAULT_STRATEGY = 0;
123
124 static {
125 /* Zip library is loaded from System.initializeSystemClass */
126 initIDs();
127 }
128
129 /**
130 * Creates a new compressor using the specified compression level.
131 * If 'nowrap' is true then the ZLIB header and checksum fields will
132 * not be used in order to support the compression format used in
133 * both GZIP and PKZIP.
134 * @param level the compression level (0-9)
135 * @param nowrap if true then use GZIP compatible compression
136 */
137 public Deflater(int level, boolean nowrap) {
138 this .level = level;
139 this .strategy = DEFAULT_STRATEGY;
140 strm = init(level, DEFAULT_STRATEGY, nowrap);
141 }
142
143 /**
144 * Creates a new compressor using the specified compression level.
145 * Compressed data will be generated in ZLIB format.
146 * @param level the compression level (0-9)
147 */
148 public Deflater(int level) {
149 this (level, false);
150 }
151
152 /**
153 * Creates a new compressor with the default compression level.
154 * Compressed data will be generated in ZLIB format.
155 */
156 public Deflater() {
157 this (DEFAULT_COMPRESSION, false);
158 }
159
160 /**
161 * Sets input data for compression. This should be called whenever
162 * needsInput() returns true indicating that more input data is required.
163 * @param b the input data bytes
164 * @param off the start offset of the data
165 * @param len the length of the data
166 * @see Deflater#needsInput
167 */
168 public synchronized void setInput(byte[] b, int off, int len) {
169 if (b == null) {
170 throw new NullPointerException();
171 }
172 if (off < 0 || len < 0 || off > b.length - len) {
173 throw new ArrayIndexOutOfBoundsException();
174 }
175 this .buf = b;
176 this .off = off;
177 this .len = len;
178 }
179
180 /**
181 * Sets input data for compression. This should be called whenever
182 * needsInput() returns true indicating that more input data is required.
183 * @param b the input data bytes
184 * @see Deflater#needsInput
185 */
186 public void setInput(byte[] b) {
187 setInput(b, 0, b.length);
188 }
189
190 /**
191 * Sets preset dictionary for compression. A preset dictionary is used
192 * when the history buffer can be predetermined. When the data is later
193 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
194 * in order to get the Adler-32 value of the dictionary required for
195 * decompression.
196 * @param b the dictionary data bytes
197 * @param off the start offset of the data
198 * @param len the length of the data
199 * @see Inflater#inflate
200 * @see Inflater#getAdler
201 */
202 public synchronized void setDictionary(byte[] b, int off, int len) {
203 if (strm == 0 || b == null) {
204 throw new NullPointerException();
205 }
206 if (off < 0 || len < 0 || off > b.length - len) {
207 throw new ArrayIndexOutOfBoundsException();
208 }
209 setDictionary(strm, b, off, len);
210 }
211
212 /**
213 * Sets preset dictionary for compression. A preset dictionary is used
214 * when the history buffer can be predetermined. When the data is later
215 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
216 * in order to get the Adler-32 value of the dictionary required for
217 * decompression.
218 * @param b the dictionary data bytes
219 * @see Inflater#inflate
220 * @see Inflater#getAdler
221 */
222 public void setDictionary(byte[] b) {
223 setDictionary(b, 0, b.length);
224 }
225
226 /**
227 * Sets the compression strategy to the specified value.
228 * @param strategy the new compression strategy
229 * @exception IllegalArgumentException if the compression strategy is
230 * invalid
231 */
232 public synchronized void setStrategy(int strategy) {
233 switch (strategy) {
234 case DEFAULT_STRATEGY:
235 case FILTERED:
236 case HUFFMAN_ONLY:
237 break;
238 default:
239 throw new IllegalArgumentException();
240 }
241 if (this .strategy != strategy) {
242 this .strategy = strategy;
243 setParams = true;
244 }
245 }
246
247 /**
248 * Sets the current compression level to the specified value.
249 * @param level the new compression level (0-9)
250 * @exception IllegalArgumentException if the compression level is invalid
251 */
252 public synchronized void setLevel(int level) {
253 if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {
254 throw new IllegalArgumentException(
255 "invalid compression level");
256 }
257 if (this .level != level) {
258 this .level = level;
259 setParams = true;
260 }
261 }
262
263 /**
264 * Returns true if the input data buffer is empty and setInput()
265 * should be called in order to provide more input.
266 * @return true if the input data buffer is empty and setInput()
267 * should be called in order to provide more input
268 */
269 public boolean needsInput() {
270 return len <= 0;
271 }
272
273 /**
274 * When called, indicates that compression should end with the current
275 * contents of the input buffer.
276 */
277 public synchronized void finish() {
278 finish = true;
279 }
280
281 /**
282 * Returns true if the end of the compressed data output stream has
283 * been reached.
284 * @return true if the end of the compressed data output stream has
285 * been reached
286 */
287 public synchronized boolean finished() {
288 return finished;
289 }
290
291 /**
292 * Fills specified buffer with compressed data. Returns actual number
293 * of bytes of compressed data. A return value of 0 indicates that
294 * needsInput() should be called in order to determine if more input
295 * data is required.
296 * @param b the buffer for the compressed data
297 * @param off the start offset of the data
298 * @param len the maximum number of bytes of compressed data
299 * @return the actual number of bytes of compressed data
300 */
301 public synchronized int deflate(byte[] b, int off, int len) {
302 if (b == null) {
303 throw new NullPointerException();
304 }
305 if (off < 0 || len < 0 || off > b.length - len) {
306 throw new ArrayIndexOutOfBoundsException();
307 }
308 return deflateBytes(b, off, len);
309 }
310
311 /**
312 * Fills specified buffer with compressed data. Returns actual number
313 * of bytes of compressed data. A return value of 0 indicates that
314 * needsInput() should be called in order to determine if more input
315 * data is required.
316 * @param b the buffer for the compressed data
317 * @return the actual number of bytes of compressed data
318 */
319 public int deflate(byte[] b) {
320 return deflate(b, 0, b.length);
321 }
322
323 /**
324 * Returns the ADLER-32 value of the uncompressed data.
325 * @return the ADLER-32 value of the uncompressed data
326 */
327 public synchronized int getAdler() {
328 ensureOpen();
329 return getAdler(strm);
330 }
331
332 /**
333 * Returns the total number of uncompressed bytes input so far.
334 *
335 * <p>Since the number of bytes may be greater than
336 * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
337 * the preferred means of obtaining this information.</p>
338 *
339 * @return the total number of uncompressed bytes input so far
340 */
341 public int getTotalIn() {
342 return (int) getBytesRead();
343 }
344
345 /**
346 * Returns the total number of uncompressed bytes input so far.</p>
347 *
348 * @return the total (non-negative) number of uncompressed bytes input so far
349 * @since 1.5
350 */
351 public synchronized long getBytesRead() {
352 ensureOpen();
353 return getBytesRead(strm);
354 }
355
356 /**
357 * Returns the total number of compressed bytes output so far.
358 *
359 * <p>Since the number of bytes may be greater than
360 * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
361 * the preferred means of obtaining this information.</p>
362 *
363 * @return the total number of compressed bytes output so far
364 */
365 public int getTotalOut() {
366 return (int) getBytesWritten();
367 }
368
369 /**
370 * Returns the total number of compressed bytes output so far.</p>
371 *
372 * @return the total (non-negative) number of compressed bytes output so far
373 * @since 1.5
374 */
375 public synchronized long getBytesWritten() {
376 ensureOpen();
377 return getBytesWritten(strm);
378 }
379
380 /**
381 * Resets deflater so that a new set of input data can be processed.
382 * Keeps current compression level and strategy settings.
383 */
384 public synchronized void reset() {
385 ensureOpen();
386 reset(strm);
387 finish = false;
388 finished = false;
389 off = len = 0;
390 }
391
392 /**
393 * Closes the compressor and discards any unprocessed input.
394 * This method should be called when the compressor is no longer
395 * being used, but will also be called automatically by the
396 * finalize() method. Once this method is called, the behavior
397 * of the Deflater object is undefined.
398 */
399 public synchronized void end() {
400 if (strm != 0) {
401 end(strm);
402 strm = 0;
403 buf = null;
404 }
405 }
406
407 /**
408 * Closes the compressor when garbage is collected.
409 */
410 protected void finalize() {
411 end();
412 }
413
414 private void ensureOpen() {
415 if (strm == 0)
416 throw new NullPointerException();
417 }
418
419 private static native void initIDs();
420
421 private native static long init(int level, int strategy,
422 boolean nowrap);
423
424 private native static void setDictionary(long strm, byte[] b,
425 int off, int len);
426
427 private native int deflateBytes(byte[] b, int off, int len);
428
429 private native static int getAdler(long strm);
430
431 private native static long getBytesRead(long strm);
432
433 private native static long getBytesWritten(long strm);
434
435 private native static void reset(long strm);
436
437 private native static void end(long strm);
438 }
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