- /*
- * @(#)Deflater.java 1.38 03/02/07
- *
- * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- package java.util.zip;
-
- /**
- * This class provides support for general purpose compression using the
- * popular ZLIB compression library. The ZLIB compression library was
- * initially developed as part of the PNG graphics standard and is not
- * protected by patents. It is fully described in the specifications at
- * the <a href="package-summary.html#package_description">java.util.zip
- * package description</a>.
- *
- * <p>The following code fragment demonstrates a trivial compression
- * and decompression of a string using <tt>Deflater</tt> and
- * <tt>Inflater</tt>.
- *
- * <blockquote><pre>
- * // Encode a String into bytes
- * String inputString = "blahblahblah\u20AC\u20AC";
- * byte[] input = inputString.getBytes("UTF-8");
- *
- * // Compress the bytes
- * byte[] output = new byte[100];
- * Deflater compresser = new Deflater();
- * compresser.setInput(input);
- * compresser.finish();
- * int compressedDataLength = compresser.deflate(output);
- *
- * // Decompress the bytes
- * Inflater decompresser = new Inflater();
- * decompresser.setInput(output, 0, compressedDataLength);
- * byte[] result = new byte[100];
- * int resultLength = decompresser.inflate(result);
- * decompresser.end();
- *
- * // Decode the bytes into a String
- * String outputString = new String(result, 0, resultLength, "UTF-8");
- * </pre></blockquote>
- *
- * @see Inflater
- * @version 1.38, 02/07/03
- * @author David Connelly
- */
- public
- class Deflater {
- private long strm;
- private byte[] buf = new byte[0];
- private int off, len;
- private int level, strategy;
- private boolean setParams;
- private boolean finish, finished;
-
- /**
- * Compression method for the deflate algorithm (the only one currently
- * supported).
- */
- public static final int DEFLATED = 8;
-
- /**
- * Compression level for no compression.
- */
- public static final int NO_COMPRESSION = 0;
-
- /**
- * Compression level for fastest compression.
- */
- public static final int BEST_SPEED = 1;
-
- /**
- * Compression level for best compression.
- */
- public static final int BEST_COMPRESSION = 9;
-
- /**
- * Default compression level.
- */
- public static final int DEFAULT_COMPRESSION = -1;
-
- /**
- * Compression strategy best used for data consisting mostly of small
- * values with a somewhat random distribution. Forces more Huffman coding
- * and less string matching.
- */
- public static final int FILTERED = 1;
-
- /**
- * Compression strategy for Huffman coding only.
- */
- public static final int HUFFMAN_ONLY = 2;
-
- /**
- * Default compression strategy.
- */
- public static final int DEFAULT_STRATEGY = 0;
-
- /*
- * Loads the ZLIB library.
- */
- static {
- java.security.AccessController.doPrivileged(
- new sun.security.action.LoadLibraryAction("zip"));
- initIDs();
- }
-
- /**
- * Creates a new compressor using the specified compression level.
- * If 'nowrap' is true then the ZLIB header and checksum fields will
- * not be used in order to support the compression format used in
- * both GZIP and PKZIP.
- * @param level the compression level (0-9)
- * @param nowrap if true then use GZIP compatible compression
- */
- public Deflater(int level, boolean nowrap) {
- this.level = level;
- this.strategy = DEFAULT_STRATEGY;
- strm = init(level, DEFAULT_STRATEGY, nowrap);
- }
-
- /**
- * Creates a new compressor using the specified compression level.
- * Compressed data will be generated in ZLIB format.
- * @param level the compression level (0-9)
- */
- public Deflater(int level) {
- this(level, false);
- }
-
- /**
- * Creates a new compressor with the default compression level.
- * Compressed data will be generated in ZLIB format.
- */
- public Deflater() {
- this(DEFAULT_COMPRESSION, false);
- }
-
- /**
- * Sets input data for compression. This should be called whenever
- * needsInput() returns true indicating that more input data is required.
- * @param b the input data bytes
- * @param off the start offset of the data
- * @param len the length of the data
- * @see Deflater#needsInput
- */
- public synchronized void setInput(byte[] b, int off, int len) {
- if (b== null) {
- throw new NullPointerException();
- }
- if (off < 0 || len < 0 || off > b.length - len) {
- throw new ArrayIndexOutOfBoundsException();
- }
- this.buf = b;
- this.off = off;
- this.len = len;
- }
-
- /**
- * Sets input data for compression. This should be called whenever
- * needsInput() returns true indicating that more input data is required.
- * @param b the input data bytes
- * @see Deflater#needsInput
- */
- public void setInput(byte[] b) {
- setInput(b, 0, b.length);
- }
-
- /**
- * Sets preset dictionary for compression. A preset dictionary is used
- * when the history buffer can be predetermined. When the data is later
- * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
- * in order to get the Adler-32 value of the dictionary required for
- * decompression.
- * @param b the dictionary data bytes
- * @param off the start offset of the data
- * @param len the length of the data
- * @see Inflater#inflate
- * @see Inflater#getAdler
- */
- public synchronized void setDictionary(byte[] b, int off, int len) {
- if (strm == 0 || b == null) {
- throw new NullPointerException();
- }
- if (off < 0 || len < 0 || off > b.length - len) {
- throw new ArrayIndexOutOfBoundsException();
- }
- setDictionary(strm, b, off, len);
- }
-
- /**
- * Sets preset dictionary for compression. A preset dictionary is used
- * when the history buffer can be predetermined. When the data is later
- * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
- * in order to get the Adler-32 value of the dictionary required for
- * decompression.
- * @param b the dictionary data bytes
- * @see Inflater#inflate
- * @see Inflater#getAdler
- */
- public void setDictionary(byte[] b) {
- setDictionary(b, 0, b.length);
- }
-
- /**
- * Sets the compression strategy to the specified value.
- * @param strategy the new compression strategy
- * @exception IllegalArgumentException if the compression strategy is
- * invalid
- */
- public synchronized void setStrategy(int strategy) {
- switch (strategy) {
- case DEFAULT_STRATEGY:
- case FILTERED:
- case HUFFMAN_ONLY:
- break;
- default:
- throw new IllegalArgumentException();
- }
- if (this.strategy != strategy) {
- this.strategy = strategy;
- setParams = true;
- }
- }
-
- /**
- * Sets the current compression level to the specified value.
- * @param level the new compression level (0-9)
- * @exception IllegalArgumentException if the compression level is invalid
- */
- public synchronized void setLevel(int level) {
- if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {
- throw new IllegalArgumentException("invalid compression level");
- }
- if (this.level != level) {
- this.level = level;
- setParams = true;
- }
- }
-
- /**
- * Returns true if the input data buffer is empty and setInput()
- * should be called in order to provide more input.
- * @return true if the input data buffer is empty and setInput()
- * should be called in order to provide more input
- */
- public boolean needsInput() {
- return len <= 0;
- }
-
- /**
- * When called, indicates that compression should end with the current
- * contents of the input buffer.
- */
- public synchronized void finish() {
- finish = true;
- }
-
- /**
- * Returns true if the end of the compressed data output stream has
- * been reached.
- * @return true if the end of the compressed data output stream has
- * been reached
- */
- public synchronized boolean finished() {
- return finished;
- }
-
- /**
- * Fills specified buffer with compressed data. Returns actual number
- * of bytes of compressed data. A return value of 0 indicates that
- * needsInput() should be called in order to determine if more input
- * data is required.
- * @param b the buffer for the compressed data
- * @param off the start offset of the data
- * @param len the maximum number of bytes of compressed data
- * @return the actual number of bytes of compressed data
- */
- public synchronized int deflate(byte[] b, int off, int len) {
- if (b == null) {
- throw new NullPointerException();
- }
- if (off < 0 || len < 0 || off > b.length - len) {
- throw new ArrayIndexOutOfBoundsException();
- }
- return deflateBytes(b, off, len);
- }
-
- /**
- * Fills specified buffer with compressed data. Returns actual number
- * of bytes of compressed data. A return value of 0 indicates that
- * needsInput() should be called in order to determine if more input
- * data is required.
- * @param b the buffer for the compressed data
- * @return the actual number of bytes of compressed data
- */
- public int deflate(byte[] b) {
- return deflate(b, 0, b.length);
- }
-
- /**
- * Returns the ADLER-32 value of the uncompressed data.
- * @return the ADLER-32 value of the uncompressed data
- */
- public synchronized int getAdler() {
- if (strm == 0) {
- throw new NullPointerException();
- }
- return getAdler(strm);
- }
-
- /**
- * Returns the total number of bytes input so far.
- * @return the total number of bytes input so far
- */
- public synchronized int getTotalIn() {
- if (strm == 0) {
- throw new NullPointerException();
- }
- return getTotalIn(strm);
- }
-
- /**
- * Returns the total number of bytes output so far.
- * @return the total number of bytes output so far
- */
- public synchronized int getTotalOut() {
- if (strm == 0) {
- throw new NullPointerException();
- }
- return getTotalOut(strm);
- }
-
- /**
- * Resets deflater so that a new set of input data can be processed.
- * Keeps current compression level and strategy settings.
- */
- public synchronized void reset() {
- if (strm == 0) {
- throw new NullPointerException();
- }
- reset(strm);
- finish = false;
- finished = false;
- off = len = 0;
- }
-
- /**
- * Closes the compressor and discards any unprocessed input.
- * This method should be called when the compressor is no longer
- * being used, but will also be called automatically by the
- * finalize() method. Once this method is called, the behavior
- * of the Deflater object is undefined.
- */
- public synchronized void end() {
- if (strm != 0) {
- end(strm);
- strm = 0;
- }
- }
-
- /**
- * Closes the compressor when garbage is collected.
- */
- protected void finalize() {
- end();
- }
-
- private static native void initIDs();
- private native static long init(int level, int strategy, boolean nowrap);
- private native static void setDictionary(long strm, byte[] b, int off,
- int len);
- private native int deflateBytes(byte[] b, int off, int len);
- private native static int getAdler(long strm);
- private native static int getTotalIn(long strm);
- private native static int getTotalOut(long strm);
- private native static void reset(long strm);
- private native static void end(long strm);
- }