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 compression 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 Inflater
70 * @author David Connelly
71 */
72 public
73 class Deflater {
74 private long strm;
75 private byte[] buf = new byte[0];
76 private int off, len;
77 private int level, strategy;
78 private boolean setParams;
79 private boolean finish, finished;
80
81 /**
82 * Compression method for the deflate algorithm (the only one currently
83 * supported).
84 */
85 public static final int DEFLATED = 8;
86
87 /**
88 * Compression level for no compression.
89 */
90 public static final int NO_COMPRESSION = 0;
91
92 /**
93 * Compression level for fastest compression.
94 */
95 public static final int BEST_SPEED = 1;
96
97 /**
98 * Compression level for best compression.
99 */
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("invalid compression level");
255 }
256 if (this.level != level) {
257 this.level = level;
258 setParams = true;
259 }
260 }
261
262 /**
263 * Returns true if the input data buffer is empty and setInput()
264 * should be called in order to provide more input.
265 * @return true if the input data buffer is empty and setInput()
266 * should be called in order to provide more input
267 */
268 public boolean needsInput() {
269 return len <= 0;
270 }
271
272 /**
273 * When called, indicates that compression should end with the current
274 * contents of the input buffer.
275 */
276 public synchronized void finish() {
277 finish = true;
278 }
279
280 /**
281 * Returns true if the end of the compressed data output stream has
282 * been reached.
283 * @return true if the end of the compressed data output stream has
284 * been reached
285 */
286 public synchronized boolean finished() {
287 return finished;
288 }
289
290 /**
291 * Fills specified buffer with compressed data. Returns actual number
292 * of bytes of compressed data. A return value of 0 indicates that
293 * needsInput() should be called in order to determine if more input
294 * data is required.
295 * @param b the buffer for the compressed data
296 * @param off the start offset of the data
297 * @param len the maximum number of bytes of compressed data
298 * @return the actual number of bytes of compressed data
299 */
300 public synchronized int deflate(byte[] b, int off, int len) {
301 if (b == null) {
302 throw new NullPointerException();
303 }
304 if (off < 0 || len < 0 || off > b.length - len) {
305 throw new ArrayIndexOutOfBoundsException();
306 }
307 return deflateBytes(b, off, len);
308 }
309
310 /**
311 * Fills specified buffer with compressed data. Returns actual number
312 * of bytes of compressed data. A return value of 0 indicates that
313 * needsInput() should be called in order to determine if more input
314 * data is required.
315 * @param b the buffer for the compressed data
316 * @return the actual number of bytes of compressed data
317 */
318 public int deflate(byte[] b) {
319 return deflate(b, 0, b.length);
320 }
321
322 /**
323 * Returns the ADLER-32 value of the uncompressed data.
324 * @return the ADLER-32 value of the uncompressed data
325 */
326 public synchronized int getAdler() {
327 ensureOpen();
328 return getAdler(strm);
329 }
330
331 /**
332 * Returns the total number of uncompressed bytes input so far.
333 *
334 * <p>Since the number of bytes may be greater than
335 * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
336 * the preferred means of obtaining this information.</p>
337 *
338 * @return the total number of uncompressed bytes input so far
339 */
340 public int getTotalIn() {
341 return (int) getBytesRead();
342 }
343
344 /**
345 * Returns the total number of uncompressed bytes input so far.</p>
346 *
347 * @return the total (non-negative) number of uncompressed bytes input so far
348 * @since 1.5
349 */
350 public synchronized long getBytesRead() {
351 ensureOpen();
352 return getBytesRead(strm);
353 }
354
355 /**
356 * Returns the total number of compressed bytes output so far.
357 *
358 * <p>Since the number of bytes may be greater than
359 * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
360 * the preferred means of obtaining this information.</p>
361 *
362 * @return the total number of compressed bytes output so far
363 */
364 public int getTotalOut() {
365 return (int) getBytesWritten();
366 }
367
368 /**
369 * Returns the total number of compressed bytes output so far.</p>
370 *
371 * @return the total (non-negative) number of compressed bytes output so far
372 * @since 1.5
373 */
374 public synchronized long getBytesWritten() {
375 ensureOpen();
376 return getBytesWritten(strm);
377 }
378
379 /**
380 * Resets deflater so that a new set of input data can be processed.
381 * Keeps current compression level and strategy settings.
382 */
383 public synchronized void reset() {
384 ensureOpen();
385 reset(strm);
386 finish = false;
387 finished = false;
388 off = len = 0;
389 }
390
391 /**
392 * Closes the compressor and discards any unprocessed input.
393 * This method should be called when the compressor is no longer
394 * being used, but will also be called automatically by the
395 * finalize() method. Once this method is called, the behavior
396 * of the Deflater object is undefined.
397 */
398 public synchronized void end() {
399 if (strm != 0) {
400 end(strm);
401 strm = 0;
402 buf = null;
403 }
404 }
405
406 /**
407 * Closes the compressor when garbage is collected.
408 */
409 protected void finalize() {
410 end();
411 }
412
413 private void ensureOpen() {
414 if (strm == 0)
415 throw new NullPointerException();
416 }
417
418 private static native void initIDs();
419 private native static long init(int level, int strategy, boolean nowrap);
420 private native static void setDictionary(long strm, byte[] b, int off,
421 int len);
422 private native int deflateBytes(byte[] b, int off, int len);
423 private native static int getAdler(long strm);
424 private native static long getBytesRead(long strm);
425 private native static long getBytesWritten(long strm);
426 private native static void reset(long strm);
427 private native static void end(long strm);
428 }
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