001: /*
002: * @(#)Deflater.java 1.43 06/10/10
003: *
004: * Copyright 1990-2006 Sun Microsystems, Inc. All Rights Reserved.
005: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
006: *
007: * This program is free software; you can redistribute it and/or
008: * modify it under the terms of the GNU General Public License version
009: * 2 only, as published by the Free Software Foundation.
010: *
011: * This program is distributed in the hope that it will be useful, but
012: * WITHOUT ANY WARRANTY; without even the implied warranty of
013: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014: * General Public License version 2 for more details (a copy is
015: * included at /legal/license.txt).
016: *
017: * You should have received a copy of the GNU General Public License
018: * version 2 along with this work; if not, write to the Free Software
019: * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020: * 02110-1301 USA
021: *
022: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
023: * Clara, CA 95054 or visit www.sun.com if you need additional
024: * information or have any questions.
025: *
026: */
027:
028: package java.util.zip;
029:
030: /**
031: * This class provides support for general purpose compression using the
032: * popular ZLIB compression library. The ZLIB compression library was
033: * initially developed as part of the PNG graphics standard and is not
034: * protected by patents. It is fully described in the specifications at
035: * the <a href="package-summary.html#package_description">java.util.zip
036: * package description</a>.
037: *
038: * <p>The following code fragment demonstrates a trivial compression
039: * and decompression of a string using <tt>Deflater</tt> and
040: * <tt>Inflater</tt>.
041: *
042: * <blockquote><pre>
043: * // Encode a String into bytes
044: * String inputString = "blahblahblah\u20AC\u20AC";
045: * byte[] input = inputString.getBytes("UTF-8");
046: *
047: * // Compress the bytes
048: * byte[] output = new byte[100];
049: * Deflater compresser = new Deflater();
050: * compresser.setInput(input);
051: * compresser.finish();
052: * int compressedDataLength = compresser.deflate(output);
053: *
054: * // Decompress the bytes
055: * Inflater decompresser = new Inflater();
056: * decompresser.setInput(output, 0, compressedDataLength);
057: * byte[] result = new byte[100];
058: * int resultLength = decompresser.inflate(result);
059: * decompresser.end();
060: *
061: * // Decode the bytes into a String
062: * String outputString = new String(result, 0, resultLength, "UTF-8");
063: * </pre></blockquote>
064: *
065: * @see Inflater
066: * @version 1.35, 05/03/00
067: * @author David Connelly
068: */
069: public class Deflater {
070: private long strm;
071: private byte[] buf = new byte[0];
072: private int off, len;
073: private int level, strategy;
074: private boolean setParams;
075: private boolean finish, finished;
076:
077: /**
078: * Compression method for the deflate algorithm (the only one currently
079: * supported).
080: */
081: public static final int DEFLATED = 8;
082:
083: /**
084: * Compression level for no compression.
085: */
086: public static final int NO_COMPRESSION = 0;
087:
088: /**
089: * Compression level for fastest compression.
090: */
091: public static final int BEST_SPEED = 1;
092:
093: /**
094: * Compression level for best compression.
095: */
096: public static final int BEST_COMPRESSION = 9;
097:
098: /**
099: * Default compression level.
100: */
101: public static final int DEFAULT_COMPRESSION = -1;
102:
103: /**
104: * Compression strategy best used for data consisting mostly of small
105: * values with a somewhat random distribution. Forces more Huffman coding
106: * and less string matching.
107: */
108: public static final int FILTERED = 1;
109:
110: /**
111: * Compression strategy for Huffman coding only.
112: */
113: public static final int HUFFMAN_ONLY = 2;
114:
115: /**
116: * Default compression strategy.
117: */
118: public static final int DEFAULT_STRATEGY = 0;
119:
120: /*
121: * Loads the ZLIB library.
122: */
123: static {
124: java.security.AccessController
125: .doPrivileged(new sun.security.action.LoadLibraryAction(
126: "zip"));
127: initIDs();
128: }
129:
130: /**
131: * Creates a new compressor using the specified compression level.
132: * If 'nowrap' is true then the ZLIB header and checksum fields will
133: * not be used in order to support the compression format used in
134: * both GZIP and PKZIP.
135: * @param level the compression level (0-9)
136: * @param nowrap if true then use GZIP compatible compression
137: */
138: public Deflater(int level, boolean nowrap) {
139: this .level = level;
140: this .strategy = DEFAULT_STRATEGY;
141: strm = init(level, DEFAULT_STRATEGY, nowrap);
142: }
143:
144: /**
145: * Creates a new compressor using the specified compression level.
146: * Compressed data will be generated in ZLIB format.
147: * @param level the compression level (0-9)
148: */
149: public Deflater(int level) {
150: this (level, false);
151: }
152:
153: /**
154: * Creates a new compressor with the default compression level.
155: * Compressed data will be generated in ZLIB format.
156: */
157: public Deflater() {
158: this (DEFAULT_COMPRESSION, false);
159: }
160:
161: /**
162: * Sets input data for compression. This should be called whenever
163: * needsInput() returns true indicating that more input data is required.
164: * @param b the input data bytes
165: * @param off the start offset of the data
166: * @param len the length of the data
167: * @see Deflater#needsInput
168: */
169: public synchronized void setInput(byte[] b, int off, int len) {
170: if (b == null) {
171: throw new NullPointerException();
172: }
173: if (off < 0 || len < 0 || off > b.length - len) {
174: throw new ArrayIndexOutOfBoundsException();
175: }
176: this .buf = b;
177: this .off = off;
178: this .len = len;
179: }
180:
181: /**
182: * Sets input data for compression. This should be called whenever
183: * needsInput() returns true indicating that more input data is required.
184: * @param b the input data bytes
185: * @see Deflater#needsInput
186: */
187: public void setInput(byte[] b) {
188: setInput(b, 0, b.length);
189: }
190:
191: /**
192: * Sets preset dictionary for compression. A preset dictionary is used
193: * when the history buffer can be predetermined. When the data is later
194: * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
195: * in order to get the Adler-32 value of the dictionary required for
196: * decompression.
197: * @param b the dictionary data bytes
198: * @param off the start offset of the data
199: * @param len the length of the data
200: * @see Inflater#inflate
201: * @see Inflater#getAdler
202: */
203: public synchronized void setDictionary(byte[] b, int off, int len) {
204: if (strm == 0 || b == null) {
205: throw new NullPointerException();
206: }
207: if (off < 0 || len < 0 || off > b.length - len) {
208: throw new ArrayIndexOutOfBoundsException();
209: }
210: setDictionary(strm, b, off, len);
211: }
212:
213: /**
214: * Sets preset dictionary for compression. A preset dictionary is used
215: * when the history buffer can be predetermined. When the data is later
216: * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
217: * in order to get the Adler-32 value of the dictionary required for
218: * decompression.
219: * @param b the dictionary data bytes
220: * @see Inflater#inflate
221: * @see Inflater#getAdler
222: */
223: public void setDictionary(byte[] b) {
224: setDictionary(b, 0, b.length);
225: }
226:
227: /**
228: * Sets the compression strategy to the specified value.
229: * @param strategy the new compression strategy
230: * @exception IllegalArgumentException if the compression strategy is
231: * invalid
232: */
233: public synchronized void setStrategy(int strategy) {
234: switch (strategy) {
235: case DEFAULT_STRATEGY:
236: case FILTERED:
237: case HUFFMAN_ONLY:
238: break;
239: default:
240: throw new IllegalArgumentException();
241: }
242: if (this .strategy != strategy) {
243: this .strategy = strategy;
244: setParams = true;
245: }
246: }
247:
248: /**
249: * Sets the current compression level to the specified value.
250: * @param level the new compression level (0-9)
251: * @exception IllegalArgumentException if the compression level is invalid
252: */
253: public synchronized void setLevel(int level) {
254: if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {
255: throw new IllegalArgumentException(
256: "invalid compression level");
257: }
258: if (this .level != level) {
259: this .level = level;
260: setParams = true;
261: }
262: }
263:
264: /**
265: * Returns true if the input data buffer is empty and setInput()
266: * should be called in order to provide more input.
267: * @return true if the input data buffer is empty and setInput()
268: * should be called in order to provide more input
269: */
270: public boolean needsInput() {
271: return len <= 0;
272: }
273:
274: /**
275: * When called, indicates that compression should end with the current
276: * contents of the input buffer.
277: */
278: public synchronized void finish() {
279: finish = true;
280: }
281:
282: /**
283: * Returns true if the end of the compressed data output stream has
284: * been reached.
285: * @return true if the end of the compressed data output stream has
286: * been reached
287: */
288: public synchronized boolean finished() {
289: return finished;
290: }
291:
292: /**
293: * Fills specified buffer with compressed data. Returns actual number
294: * of bytes of compressed data. A return value of 0 indicates that
295: * needsInput() should be called in order to determine if more input
296: * data is required.
297: * @param b the buffer for the compressed data
298: * @param off the start offset of the data
299: * @param len the maximum number of bytes of compressed data
300: * @return the actual number of bytes of compressed data
301: */
302: public synchronized int deflate(byte[] b, int off, int len) {
303: if (b == null) {
304: throw new NullPointerException();
305: }
306: if (off < 0 || len < 0 || off > b.length - len) {
307: throw new ArrayIndexOutOfBoundsException();
308: }
309: return deflateBytes(b, off, len);
310: }
311:
312: /**
313: * Fills specified buffer with compressed data. Returns actual number
314: * of bytes of compressed data. A return value of 0 indicates that
315: * needsInput() should be called in order to determine if more input
316: * data is required.
317: * @param b the buffer for the compressed data
318: * @return the actual number of bytes of compressed data
319: */
320: public int deflate(byte[] b) {
321: return deflate(b, 0, b.length);
322: }
323:
324: /**
325: * Returns the ADLER-32 value of the uncompressed data.
326: * @return the ADLER-32 value of the uncompressed data
327: */
328: public synchronized int getAdler() {
329: if (strm == 0) {
330: throw new NullPointerException();
331: }
332: return getAdler(strm);
333: }
334:
335: /**
336: * Returns the total number of bytes input so far.
337: * @return the total number of bytes input so far
338: */
339: public synchronized int getTotalIn() {
340: if (strm == 0) {
341: throw new NullPointerException();
342: }
343: return getTotalIn(strm);
344: }
345:
346: /**
347: * Returns the total number of bytes output so far.
348: * @return the total number of bytes output so far
349: */
350: public synchronized int getTotalOut() {
351: if (strm == 0) {
352: throw new NullPointerException();
353: }
354: return getTotalOut(strm);
355: }
356:
357: /**
358: * Resets deflater so that a new set of input data can be processed.
359: * Keeps current compression level and strategy settings.
360: */
361: public synchronized void reset() {
362: if (strm == 0) {
363: throw new NullPointerException();
364: }
365: reset(strm);
366: finish = false;
367: finished = false;
368: off = len = 0;
369: }
370:
371: /**
372: * Closes the compressor and discards any unprocessed input.
373: * This method should be called when the compressor is no longer
374: * being used, but will also be called automatically by the
375: * finalize() method. Once this method is called, the behavior
376: * of the Deflater object is undefined.
377: */
378: public synchronized void end() {
379: if (strm != 0) {
380: end(strm);
381: strm = 0;
382: }
383: }
384:
385: /**
386: * Closes the compressor when garbage is collected.
387: */
388: protected void finalize() {
389: end();
390: }
391:
392: private static native void initIDs();
393:
394: private native static long init(int level, int strategy,
395: boolean nowrap);
396:
397: private native static void setDictionary(long strm, byte[] b,
398: int off, int len);
399:
400: private native int deflateBytes(byte[] b, int off, int len);
401:
402: private native static int getAdler(long strm);
403:
404: private native static int getTotalIn(long strm);
405:
406: private native static int getTotalOut(long strm);
407:
408: private native static void reset(long strm);
409:
410: private native static void end(long strm);
411: }
|