1 /*
2 * Copyright (c) 1996, 2017, 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
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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 *
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20 *
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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 {@code Deflater} and
38 * {@code Inflater}.
39 *
40 * <blockquote><pre>
41 * try {
42 * // Encode a String into bytes
43 * String inputString = "blahblahblah";
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 * compresser.end();
53 *
54 * // Decompress the bytes
55 * Inflater decompresser = new Inflater();
56 * decompresser.setInput(output, 0, compressedDataLength);
57 * byte[] result = new byte[100];
58 * int resultLength = decompresser.inflate(result);
59 * decompresser.end();
60 *
61 * // Decode the bytes into a String
62 * String outputString = new String(result, 0, resultLength, "UTF-8");
63 * } catch(java.io.UnsupportedEncodingException ex) {
64 * // handle
65 * } catch (java.util.zip.DataFormatException ex) {
66 * // handle
67 * }
68 * </pre></blockquote>
69 *
70 * @apiNote
71 * To release resources used by this {@code Deflater}, the {@link #end()} method
72 * should be called explicitly. Subclasses are responsible for the cleanup of resources
73 * acquired by the subclass. Subclasses that override {@link #finalize()} in order
74 * to perform cleanup should be modified to use alternative cleanup mechanisms such
75 * as {@link java.lang.ref.Cleaner} and remove the overriding {@code finalize} method.
76 *
77 * @implSpec
78 * If this {@code Deflater} has been subclassed and the {@code end} method has been
79 * overridden, the {@code end} method will be called by the finalization when the
80 * deflater is unreachable. But the subclasses should not depend on this specific
81 * implementation; the finalization is not reliable and the {@code finalize} method
82 * is deprecated to be removed.
83 *
84 * @see Inflater
85 * @author David Connelly
86 * @since 1.1
87 */
88
89 public class Deflater {
90
91 private final ZStreamRef zsRef;
92 private byte[] buf = new byte[0];
93 private int off, len;
94 private int level, strategy;
95 private boolean setParams;
96 private boolean finish, finished;
97 private long bytesRead;
98 private long bytesWritten;
99
100 /**
101 * Compression method for the deflate algorithm (the only one currently
102 * supported).
103 */
104 public static final int DEFLATED = 8;
105
106 /**
107 * Compression level for no compression.
108 */
109 public static final int NO_COMPRESSION = 0;
110
111 /**
112 * Compression level for fastest compression.
113 */
114 public static final int BEST_SPEED = 1;
115
116 /**
117 * Compression level for best compression.
118 */
119 public static final int BEST_COMPRESSION = 9;
120
121 /**
122 * Default compression level.
123 */
124 public static final int DEFAULT_COMPRESSION = -1;
125
126 /**
127 * Compression strategy best used for data consisting mostly of small
128 * values with a somewhat random distribution. Forces more Huffman coding
129 * and less string matching.
130 */
131 public static final int FILTERED = 1;
132
133 /**
134 * Compression strategy for Huffman coding only.
135 */
136 public static final int HUFFMAN_ONLY = 2;
137
138 /**
139 * Default compression strategy.
140 */
141 public static final int DEFAULT_STRATEGY = 0;
142
143 /**
144 * Compression flush mode used to achieve best compression result.
145 *
146 * @see Deflater#deflate(byte[], int, int, int)
147 * @since 1.7
148 */
149 public static final int NO_FLUSH = 0;
150
151 /**
152 * Compression flush mode used to flush out all pending output; may
153 * degrade compression for some compression algorithms.
154 *
155 * @see Deflater#deflate(byte[], int, int, int)
156 * @since 1.7
157 */
158 public static final int SYNC_FLUSH = 2;
159
160 /**
161 * Compression flush mode used to flush out all pending output and
162 * reset the deflater. Using this mode too often can seriously degrade
163 * compression.
164 *
165 * @see Deflater#deflate(byte[], int, int, int)
166 * @since 1.7
167 */
168 public static final int FULL_FLUSH = 3;
169
170 static {
171 ZipUtils.loadLibrary();
172 initIDs();
173 }
174
175 /**
176 * Creates a new compressor using the specified compression level.
177 * If 'nowrap' is true then the ZLIB header and checksum fields will
178 * not be used in order to support the compression format used in
179 * both GZIP and PKZIP.
180 * @param level the compression level (0-9)
181 * @param nowrap if true then use GZIP compatible compression
182 */
183 public Deflater(int level, boolean nowrap) {
184 this.level = level;
185 this.strategy = DEFAULT_STRATEGY;
186 this.zsRef = ZStreamRef.get(this,
187 () -> init(level, DEFAULT_STRATEGY, nowrap),
188 Deflater::end);
189 }
190
191 /**
192 * Creates a new compressor using the specified compression level.
193 * Compressed data will be generated in ZLIB format.
194 * @param level the compression level (0-9)
195 */
196 public Deflater(int level) {
197 this(level, false);
198 }
199
200 /**
201 * Creates a new compressor with the default compression level.
202 * Compressed data will be generated in ZLIB format.
203 */
204 public Deflater() {
205 this(DEFAULT_COMPRESSION, false);
206 }
207
208 /**
209 * Sets input data for compression. This should be called whenever
210 * needsInput() returns true indicating that more input data is required.
211 * @param b the input data bytes
212 * @param off the start offset of the data
213 * @param len the length of the data
214 * @see Deflater#needsInput
215 */
216 public void setInput(byte[] b, int off, int len) {
217 if (b== null) {
218 throw new NullPointerException();
219 }
220 if (off < 0 || len < 0 || off > b.length - len) {
221 throw new ArrayIndexOutOfBoundsException();
222 }
223 synchronized (zsRef) {
224 this.buf = b;
225 this.off = off;
226 this.len = len;
227 }
228 }
229
230 /**
231 * Sets input data for compression. This should be called whenever
232 * needsInput() returns true indicating that more input data is required.
233 * @param b the input data bytes
234 * @see Deflater#needsInput
235 */
236 public void setInput(byte[] b) {
237 setInput(b, 0, b.length);
238 }
239
240 /**
241 * Sets preset dictionary for compression. A preset dictionary is used
242 * when the history buffer can be predetermined. When the data is later
243 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
244 * in order to get the Adler-32 value of the dictionary required for
245 * decompression.
246 * @param b the dictionary data bytes
247 * @param off the start offset of the data
248 * @param len the length of the data
249 * @see Inflater#inflate
250 * @see Inflater#getAdler
251 */
252 public void setDictionary(byte[] b, int off, int len) {
253 if (b == null) {
254 throw new NullPointerException();
255 }
256 if (off < 0 || len < 0 || off > b.length - len) {
257 throw new ArrayIndexOutOfBoundsException();
258 }
259 synchronized (zsRef) {
260 ensureOpen();
261 setDictionary(zsRef.address(), b, off, len);
262 }
263 }
264
265 /**
266 * Sets preset dictionary for compression. A preset dictionary is used
267 * when the history buffer can be predetermined. When the data is later
268 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
269 * in order to get the Adler-32 value of the dictionary required for
270 * decompression.
271 * @param b the dictionary data bytes
272 * @see Inflater#inflate
273 * @see Inflater#getAdler
274 */
275 public void setDictionary(byte[] b) {
276 setDictionary(b, 0, b.length);
277 }
278
279 /**
280 * Sets the compression strategy to the specified value.
281 *
282 * <p> If the compression strategy is changed, the next invocation
283 * of {@code deflate} will compress the input available so far with
284 * the old strategy (and may be flushed); the new strategy will take
285 * effect only after that invocation.
286 *
287 * @param strategy the new compression strategy
288 * @exception IllegalArgumentException if the compression strategy is
289 * invalid
290 */
291 public void setStrategy(int strategy) {
292 switch (strategy) {
293 case DEFAULT_STRATEGY:
294 case FILTERED:
295 case HUFFMAN_ONLY:
296 break;
297 default:
298 throw new IllegalArgumentException();
299 }
300 synchronized (zsRef) {
301 if (this.strategy != strategy) {
302 this.strategy = strategy;
303 setParams = true;
304 }
305 }
306 }
307
308 /**
309 * Sets the compression level to the specified value.
310 *
311 * <p> If the compression level is changed, the next invocation
312 * of {@code deflate} will compress the input available so far
313 * with the old level (and may be flushed); the new level will
314 * take effect only after that invocation.
315 *
316 * @param level the new compression level (0-9)
317 * @exception IllegalArgumentException if the compression level is invalid
318 */
319 public void setLevel(int level) {
320 if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {
321 throw new IllegalArgumentException("invalid compression level");
322 }
323 synchronized (zsRef) {
324 if (this.level != level) {
325 this.level = level;
326 setParams = true;
327 }
328 }
329 }
330
331 /**
332 * Returns true if the input data buffer is empty and setInput()
333 * should be called in order to provide more input.
334 * @return true if the input data buffer is empty and setInput()
335 * should be called in order to provide more input
336 */
337 public boolean needsInput() {
338 synchronized (zsRef) {
339 return len <= 0;
340 }
341 }
342
343 /**
344 * When called, indicates that compression should end with the current
345 * contents of the input buffer.
346 */
347 public void finish() {
348 synchronized (zsRef) {
349 finish = true;
350 }
351 }
352
353 /**
354 * Returns true if the end of the compressed data output stream has
355 * been reached.
356 * @return true if the end of the compressed data output stream has
357 * been reached
358 */
359 public boolean finished() {
360 synchronized (zsRef) {
361 return finished;
362 }
363 }
364
365 /**
366 * Compresses the input data and fills specified buffer with compressed
367 * data. Returns actual number of bytes of compressed data. A return value
368 * of 0 indicates that {@link #needsInput() needsInput} should be called
369 * in order to determine if more input data is required.
370 *
371 * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.
372 * An invocation of this method of the form {@code deflater.deflate(b, off, len)}
373 * yields the same result as the invocation of
374 * {@code deflater.deflate(b, off, len, Deflater.NO_FLUSH)}.
375 *
376 * @param b the buffer for the compressed data
377 * @param off the start offset of the data
378 * @param len the maximum number of bytes of compressed data
379 * @return the actual number of bytes of compressed data written to the
380 * output buffer
381 */
382 public int deflate(byte[] b, int off, int len) {
383 return deflate(b, off, len, NO_FLUSH);
384 }
385
386 /**
387 * Compresses the input data and fills specified buffer with compressed
388 * data. Returns actual number of bytes of compressed data. A return value
389 * of 0 indicates that {@link #needsInput() needsInput} should be called
390 * in order to determine if more input data is required.
391 *
392 * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.
393 * An invocation of this method of the form {@code deflater.deflate(b)}
394 * yields the same result as the invocation of
395 * {@code deflater.deflate(b, 0, b.length, Deflater.NO_FLUSH)}.
396 *
397 * @param b the buffer for the compressed data
398 * @return the actual number of bytes of compressed data written to the
399 * output buffer
400 */
401 public int deflate(byte[] b) {
402 return deflate(b, 0, b.length, NO_FLUSH);
403 }
404
405 /**
406 * Compresses the input data and fills the specified buffer with compressed
407 * data. Returns actual number of bytes of data compressed.
408 *
409 * <p>Compression flush mode is one of the following three modes:
410 *
411 * <ul>
412 * <li>{@link #NO_FLUSH}: allows the deflater to decide how much data
413 * to accumulate, before producing output, in order to achieve the best
414 * compression (should be used in normal use scenario). A return value
415 * of 0 in this flush mode indicates that {@link #needsInput()} should
416 * be called in order to determine if more input data is required.
417 *
418 * <li>{@link #SYNC_FLUSH}: all pending output in the deflater is flushed,
419 * to the specified output buffer, so that an inflater that works on
420 * compressed data can get all input data available so far (In particular
421 * the {@link #needsInput()} returns {@code true} after this invocation
422 * if enough output space is provided). Flushing with {@link #SYNC_FLUSH}
423 * may degrade compression for some compression algorithms and so it
424 * should be used only when necessary.
425 *
426 * <li>{@link #FULL_FLUSH}: all pending output is flushed out as with
427 * {@link #SYNC_FLUSH}. The compression state is reset so that the inflater
428 * that works on the compressed output data can restart from this point
429 * if previous compressed data has been damaged or if random access is
430 * desired. Using {@link #FULL_FLUSH} too often can seriously degrade
431 * compression.
432 * </ul>
433 *
434 * <p>In the case of {@link #FULL_FLUSH} or {@link #SYNC_FLUSH}, if
435 * the return value is {@code len}, the space available in output
436 * buffer {@code b}, this method should be invoked again with the same
437 * {@code flush} parameter and more output space. Make sure that
438 * {@code len} is greater than 6 to avoid flush marker (5 bytes) being
439 * repeatedly output to the output buffer every time this method is
440 * invoked.
441 *
442 * @param b the buffer for the compressed data
443 * @param off the start offset of the data
444 * @param len the maximum number of bytes of compressed data
445 * @param flush the compression flush mode
446 * @return the actual number of bytes of compressed data written to
447 * the output buffer
448 *
449 * @throws IllegalArgumentException if the flush mode is invalid
450 * @since 1.7
451 */
452 public int deflate(byte[] b, int off, int len, int flush) {
453 if (b == null) {
454 throw new NullPointerException();
455 }
456 if (off < 0 || len < 0 || off > b.length - len) {
457 throw new ArrayIndexOutOfBoundsException();
458 }
459 synchronized (zsRef) {
460 ensureOpen();
461 if (flush == NO_FLUSH || flush == SYNC_FLUSH ||
462 flush == FULL_FLUSH) {
463 int thisLen = this.len;
464 int n = deflateBytes(zsRef.address(), b, off, len, flush);
465 bytesWritten += n;
466 bytesRead += (thisLen - this.len);
467 return n;
468 }
469 throw new IllegalArgumentException();
470 }
471 }
472
473 /**
474 * Returns the ADLER-32 value of the uncompressed data.
475 * @return the ADLER-32 value of the uncompressed data
476 */
477 public int getAdler() {
478 synchronized (zsRef) {
479 ensureOpen();
480 return getAdler(zsRef.address());
481 }
482 }
483
484 /**
485 * Returns the total number of uncompressed bytes input so far.
486 *
487 * <p>Since the number of bytes may be greater than
488 * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
489 * the preferred means of obtaining this information.</p>
490 *
491 * @return the total number of uncompressed bytes input so far
492 */
493 public int getTotalIn() {
494 return (int) getBytesRead();
495 }
496
497 /**
498 * Returns the total number of uncompressed bytes input so far.
499 *
500 * @return the total (non-negative) number of uncompressed bytes input so far
501 * @since 1.5
502 */
503 public long getBytesRead() {
504 synchronized (zsRef) {
505 ensureOpen();
506 return bytesRead;
507 }
508 }
509
510 /**
511 * Returns the total number of compressed bytes output so far.
512 *
513 * <p>Since the number of bytes may be greater than
514 * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
515 * the preferred means of obtaining this information.</p>
516 *
517 * @return the total number of compressed bytes output so far
518 */
519 public int getTotalOut() {
520 return (int) getBytesWritten();
521 }
522
523 /**
524 * Returns the total number of compressed bytes output so far.
525 *
526 * @return the total (non-negative) number of compressed bytes output so far
527 * @since 1.5
528 */
529 public long getBytesWritten() {
530 synchronized (zsRef) {
531 ensureOpen();
532 return bytesWritten;
533 }
534 }
535
536 /**
537 * Resets deflater so that a new set of input data can be processed.
538 * Keeps current compression level and strategy settings.
539 */
540 public void reset() {
541 synchronized (zsRef) {
542 ensureOpen();
543 reset(zsRef.address());
544 finish = false;
545 finished = false;
546 off = len = 0;
547 bytesRead = bytesWritten = 0;
548 }
549 }
550
551 /**
552 * Closes the compressor and discards any unprocessed input.
553 *
554 * This method should be called when the compressor is no longer
555 * being used. Once this method is called, the behavior of the
556 * Deflater object is undefined.
557 */
558 public void end() {
559 synchronized (zsRef) {
560 zsRef.clean();
561 buf = null;
562 }
563 }
564
565 /**
566 * Closes the compressor when garbage is collected.
567 *
568 * @deprecated The {@code finalize} method has been deprecated and will be
569 * removed. It is implemented as a no-op. Subclasses that override
570 * {@code finalize} in order to perform cleanup should be modified to use
571 * alternative cleanup mechanisms and to remove the overriding {@code finalize}
572 * method. The recommended cleanup for compressor is to explicitly call
573 * {@code end} method when it is no longer in use. If the {@code end} is
574 * not invoked explicitly the resource of the compressor will be released
575 * when the instance becomes unreachable.
576 */
577 @Deprecated(since="9", forRemoval=true)
578 protected void finalize() {}
579
580 private void ensureOpen() {
581 assert Thread.holdsLock(zsRef);
582 if (zsRef.address() == 0)
583 throw new NullPointerException("Deflater has been closed");
584 }
585
586 private static native void initIDs();
587 private static native long init(int level, int strategy, boolean nowrap);
588 private static native void setDictionary(long addr, byte[] b, int off, int len);
589 private native int deflateBytes(long addr, byte[] b, int off, int len,
590 int flush);
591 private static native int getAdler(long addr);
592 private static native void reset(long addr);
593 private static native void end(long addr);
594 }