/* * Copyright (c) 1996, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ 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> * try { *     // Encode a String into bytes *     String inputString = "blahblahblah"; *     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); *     compresser.end(); * *     // 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"); * } catch(java.io.UnsupportedEncodingException ex) { *     // handle * } catch (java.util.zip.DataFormatException ex) { *     // handle * } * </pre></blockquote> * * @see         Inflater * @author      David Connelly */publicclass Deflater {     private final ZStreamRef zsRef;    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;     /**     * Compression flush mode used to achieve best compression result.     *     * @see Deflater#deflate(byte[], int, int, int)     * @since 1.7     */    public static final int NO_FLUSH = 0;     /**     * Compression flush mode used to flush out all pending output; may     * degrade compression for some compression algorithms.     *     * @see Deflater#deflate(byte[], int, int, int)     * @since 1.7     */    public static final int SYNC_FLUSH = 2;     /**     * Compression flush mode used to flush out all pending output and     * reset the deflater. Using this mode too often can seriously degrade     * compression.     *     * @see Deflater#deflate(byte[], int, int, int)     * @since 1.7     */    public static final int FULL_FLUSH = 3;     static {        /* Zip library is loaded from System.initializeSystemClass */        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;        this.zsRef = new ZStreamRef(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 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();        }        synchronized (zsRef) {            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 void setDictionary(byte[] b, int off, int len) {        if (b == null) {            throw new NullPointerException();        }        if (off < 0 || len < 0 || off > b.length - len) {            throw new ArrayIndexOutOfBoundsException();        }        synchronized (zsRef) {            ensureOpen();            setDictionary(zsRef.address(), 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 void setStrategy(int strategy) {        switch (strategy) {          case DEFAULT_STRATEGY:          case FILTERED:          case HUFFMAN_ONLY:            break;          default:            throw new IllegalArgumentException();        }        synchronized (zsRef) {            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 void setLevel(int level) {        if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {            throw new IllegalArgumentException("invalid compression level");        }        synchronized (zsRef) {            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 void finish() {        synchronized (zsRef) {            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 boolean finished() {        synchronized (zsRef) {            return finished;        }    }     /**     * Compresses the input data and fills specified buffer with compressed     * data. Returns actual number of bytes of compressed data. A return value     * of 0 indicates that {@link #needsInput() needsInput} should be called     * in order to determine if more input data is required.     *     * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.     * An invocation of this method of the form {@code deflater.deflate(b, off, len)}     * yields the same result as the invocation of     * {@code deflater.deflate(b, off, len, Deflater.NO_FLUSH)}.     *     * @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 written to the     *         output buffer     */    public int deflate(byte[] b, int off, int len) {        return deflate(b, off, len, NO_FLUSH);    }     /**     * Compresses the input data and fills specified buffer with compressed     * data. Returns actual number of bytes of compressed data. A return value     * of 0 indicates that {@link #needsInput() needsInput} should be called     * in order to determine if more input data is required.     *     * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.     * An invocation of this method of the form {@code deflater.deflate(b)}     * yields the same result as the invocation of     * {@code deflater.deflate(b, 0, b.length, Deflater.NO_FLUSH)}.     *     * @param b the buffer for the compressed data     * @return the actual number of bytes of compressed data written to the     *         output buffer     */    public int deflate(byte[] b) {        return deflate(b, 0, b.length, NO_FLUSH);    }     /**     * Compresses the input data and fills the specified buffer with compressed     * data. Returns actual number of bytes of data compressed.     *     * <p>Compression flush mode is one of the following three modes:     *     * <ul>     * <li>{@link #NO_FLUSH}: allows the deflater to decide how much data     * to accumulate, before producing output, in order to achieve the best     * compression (should be used in normal use scenario). A return value     * of 0 in this flush mode indicates that {@link #needsInput()} should     * be called in order to determine if more input data is required.     *     * <li>{@link #SYNC_FLUSH}: all pending output in the deflater is flushed,     * to the specified output buffer, so that an inflater that works on     * compressed data can get all input data available so far (In particular     * the {@link #needsInput()} returns {@code true} after this invocation     * if enough output space is provided). Flushing with {@link #SYNC_FLUSH}     * may degrade compression for some compression algorithms and so it     * should be used only when necessary.     *     * <li>{@link #FULL_FLUSH}: all pending output is flushed out as with     * {@link #SYNC_FLUSH}. The compression state is reset so that the inflater     * that works on the compressed output data can restart from this point     * if previous compressed data has been damaged or if random access is     * desired. Using {@link #FULL_FLUSH} too often can seriously degrade     * compression.     * </ul>     *     * <p>In the case of {@link #FULL_FLUSH} or {@link #SYNC_FLUSH}, if     * the return value is {@code len}, the space available in output     * buffer {@code b}, this method should be invoked again with the same     * {@code flush} parameter and more output space.     *     * @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     * @param flush the compression flush mode     * @return the actual number of bytes of compressed data written to     *         the output buffer     *     * @throws IllegalArgumentException if the flush mode is invalid     * @since 1.7     */    public int deflate(byte[] b, int off, int len, int flush) {        if (b == null) {            throw new NullPointerException();        }        if (off < 0 || len < 0 || off > b.length - len) {            throw new ArrayIndexOutOfBoundsException();        }        synchronized (zsRef) {            ensureOpen();            if (flush == NO_FLUSH || flush == SYNC_FLUSH ||                flush == FULL_FLUSH)                return deflateBytes(zsRef.address(), b, off, len, flush);            throw new IllegalArgumentException();        }    }     /**     * Returns the ADLER-32 value of the uncompressed data.     * @return the ADLER-32 value of the uncompressed data     */    public int getAdler() {        synchronized (zsRef) {            ensureOpen();            return getAdler(zsRef.address());        }    }     /**     * Returns the total number of uncompressed bytes input so far.     *     * <p>Since the number of bytes may be greater than     * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now     * the preferred means of obtaining this information.</p>     *     * @return the total number of uncompressed bytes input so far     */    public int getTotalIn() {        return (int) getBytesRead();    }     /**     * Returns the total number of uncompressed bytes input so far.</p>     *     * @return the total (non-negative) number of uncompressed bytes input so far     * @since 1.5     */    public long getBytesRead() {        synchronized (zsRef) {            ensureOpen();            return getBytesRead(zsRef.address());        }    }     /**     * Returns the total number of compressed bytes output so far.     *     * <p>Since the number of bytes may be greater than     * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now     * the preferred means of obtaining this information.</p>     *     * @return the total number of compressed bytes output so far     */    public int getTotalOut() {        return (int) getBytesWritten();    }     /**     * Returns the total number of compressed bytes output so far.</p>     *     * @return the total (non-negative) number of compressed bytes output so far     * @since 1.5     */    public long getBytesWritten() {        synchronized (zsRef) {            ensureOpen();            return getBytesWritten(zsRef.address());        }    }     /**     * Resets deflater so that a new set of input data can be processed.     * Keeps current compression level and strategy settings.     */    public void reset() {        synchronized (zsRef) {

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