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 }
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