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/*
 * Copyright (c) 1996, 2018, 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
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 *
 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package java.util.zip;

import java.lang.ref.Cleaner.Cleanable;
import java.lang.ref.Reference;
import java.nio.ByteBuffer;
import java.nio.ReadOnlyBufferException;
import java.util.Objects;

import jdk.internal.ref.CleanerFactory;
import sun.nio.ch.DirectBuffer;


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 java.util.zip
package description.

 This class deflates sequences of bytes into ZLIB compressed data format. The input byte sequence is provided in either byte array or byte buffer, via one of the setInput() methods. The output byte sequence is written to the output byte array or byte buffer passed to the deflate() methods. 
 The following code fragment demonstrates a trivial compression and decompression of a string using Deflater and Inflater. 
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
}



Author:     David Connelly
See Also:
API Note: To release resources used by this Deflater, the end() method should be called explicitly. Subclasses are responsible for the cleanup of resources acquired by the subclass. Subclasses that override Object.finalize() in order to perform cleanup should be modified to use alternative cleanup mechanisms such as Cleaner and remove the overriding finalize method.
Since:1.1
/**
 * 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>
 * This class deflates sequences of bytes into ZLIB compressed data format.
 * The input byte sequence is provided in either byte array or byte buffer,
 * via one of the {@code setInput()} methods. The output byte sequence is
 * written to the output byte array or byte buffer passed to the
 * {@code deflate()} methods.
 * <p>
 * The following code fragment demonstrates a trivial compression
 * and decompression of a string using {@code Deflater} and
 * {@code Inflater}.
 *
 * <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>
 *
 * @apiNote
 * To release resources used by this {@code Deflater}, the {@link #end()} method
 * should be called explicitly. Subclasses are responsible for the cleanup of resources
 * acquired by the subclass. Subclasses that override {@link #finalize()} in order
 * to perform cleanup should be modified to use alternative cleanup mechanisms such
 * as {@link java.lang.ref.Cleaner} and remove the overriding {@code finalize} method.
 *
 * @see         Inflater
 * @author      David Connelly
 * @since 1.1
 */

public class Deflater {

    private final DeflaterZStreamRef zsRef;
    private ByteBuffer input = ZipUtils.defaultBuf;
    private byte[] inputArray;
    private int inputPos, inputLim;
    private int level, strategy;
    private boolean setParams;
    private boolean finish, finished;
    private long bytesRead;
    private long bytesWritten;

    
Compression method for the deflate algorithm (the only one currently
supported).

/**
     * Compression method for the deflate algorithm (the only one currently
     * supported).
     */
    public static final int DEFLATED = 8;

    
Compression level for no compression.

/**
     * Compression level for no compression.
     */
    public static final int NO_COMPRESSION = 0;

    
Compression level for fastest compression.

/**
     * Compression level for fastest compression.
     */
    public static final int BEST_SPEED = 1;

    
Compression level for best compression.

/**
     * Compression level for best compression.
     */
    public static final int BEST_COMPRESSION = 9;

    
Default compression level.

/**
     * 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.

/**
     * 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.

/**
     * Compression strategy for Huffman coding only.
     */
    public static final int HUFFMAN_ONLY = 2;

    
Default compression strategy.

/**
     * Default compression strategy.
     */
    public static final int DEFAULT_STRATEGY = 0;

    
Compression flush mode used to achieve best compression result.

See Also:
  • deflate.deflate(byte[], int, int, int)
Since:1.7
/**
     * 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 Also:
  • deflate.deflate(byte[], int, int, int)
Since:1.7
/**
     * 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 Also:
  • deflate.deflate(byte[], int, int, int)
Since:1.7
/**
     * 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;

    
Flush mode to use at the end of output. Can only be provided by the user by way of finish(). 
/**
     * Flush mode to use at the end of output.  Can only be provided by the
     * user by way of {@link #finish()}.
     */
    private static final int FINISH = 4;

    static {
        ZipUtils.loadLibrary();
    }

    
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.

Params:
  • level – the compression level (0-9)
  • nowrap – if true then use GZIP compatible compression
/**
     * 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 DeflaterZStreamRef(this,
                init(level, DEFAULT_STRATEGY, nowrap));
    }

    
Creates a new compressor using the specified compression level.
Compressed data will be generated in ZLIB format.

Params:
  • level – the compression level (0-9)
/**
     * 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.

/**
     * 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.

 One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required. 
Params:
  • input – the input data bytes
  • off – the start offset of the data
  • len – the length of the data
See Also:
/**
     * Sets input data for compression.
     * <p>
     * One of the {@code setInput()} methods should be called whenever
     * {@code needsInput()} returns true indicating that more input data
     * is required.
     * @param input 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[] input, int off, int len) {
        if (off < 0 || len < 0 || off > input.length - len) {
            throw new ArrayIndexOutOfBoundsException();
        }
        synchronized (zsRef) {
            this.input = null;
            this.inputArray = input;
            this.inputPos = off;
            this.inputLim = off + len;
        }
    }

    
Sets input data for compression.

 One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required. 
Params:
  • input – the input data bytes
See Also:
/**
     * Sets input data for compression.
     * <p>
     * One of the {@code setInput()} methods should be called whenever
     * {@code needsInput()} returns true indicating that more input data
     * is required.
     * @param input the input data bytes
     * @see Deflater#needsInput
     */
    public void setInput(byte[] input) {
        setInput(input, 0, input.length);
    }

    
Sets input data for compression.

 One of the setInput() methods should be called whenever needsInput() returns true indicating that more input data is required. 

The given buffer's position will be advanced as deflate
operations are performed, up to the buffer's limit.
The input buffer may be modified (refilled) between deflate
operations; doing so is equivalent to creating a new buffer
and setting it with this method.


Modifying the input buffer's contents, position, or limit
concurrently with an deflate operation will result in
undefined behavior, which may include incorrect operation
results or operation failure.

Params:
  • input – the input data bytes
See Also:
Since:11
/**
     * Sets input data for compression.
     * <p>
     * One of the {@code setInput()} methods should be called whenever
     * {@code needsInput()} returns true indicating that more input data
     * is required.
     * <p>
     * The given buffer's position will be advanced as deflate
     * operations are performed, up to the buffer's limit.
     * The input buffer may be modified (refilled) between deflate
     * operations; doing so is equivalent to creating a new buffer
     * and setting it with this method.
     * <p>
     * Modifying the input buffer's contents, position, or limit
     * concurrently with an deflate operation will result in
     * undefined behavior, which may include incorrect operation
     * results or operation failure.
     *
     * @param input the input data bytes
     * @see Deflater#needsInput
     * @since 11
     */
    public void setInput(ByteBuffer input) {
        Objects.requireNonNull(input);
        synchronized (zsRef) {
            this.input = input;
            this.inputArray = null;
        }
    }

    
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.

Params:
  • dictionary – the dictionary data bytes
  • off – the start offset of the data
  • len – the length of the data
See Also:
/**
     * 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 dictionary 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[] dictionary, int off, int len) {
        if (off < 0 || len < 0 || off > dictionary.length - len) {
            throw new ArrayIndexOutOfBoundsException();
        }
        synchronized (zsRef) {
            ensureOpen();
            setDictionary(zsRef.address(), dictionary, 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.

Params:
  • dictionary – the dictionary data bytes
See Also:
/**
     * 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 dictionary the dictionary data bytes
     * @see Inflater#inflate
     * @see Inflater#getAdler
     */
    public void setDictionary(byte[] dictionary) {
        setDictionary(dictionary, 0, dictionary.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.


The bytes in given byte buffer will be fully consumed by this method.  On
return, its position will equal its limit.

Params:
  • dictionary – the dictionary data bytes
See Also:
/**
     * 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.
     * <p>
     * The bytes in given byte buffer will be fully consumed by this method.  On
     * return, its position will equal its limit.
     *
     * @param dictionary the dictionary data bytes
     * @see Inflater#inflate
     * @see Inflater#getAdler
     */
    public void setDictionary(ByteBuffer dictionary) {
        synchronized (zsRef) {
            int position = dictionary.position();
            int remaining = Math.max(dictionary.limit() - position, 0);
            ensureOpen();
            if (dictionary.isDirect()) {
                long address = ((DirectBuffer) dictionary).address();
                try {
                    setDictionaryBuffer(zsRef.address(), address + position, remaining);
                } finally {
                    Reference.reachabilityFence(dictionary);
                }
            } else {
                byte[] array = ZipUtils.getBufferArray(dictionary);
                int offset = ZipUtils.getBufferOffset(dictionary);
                setDictionary(zsRef.address(), array, offset + position, remaining);
            }
            dictionary.position(position + remaining);
        }
    }

    
Sets the compression strategy to the specified value.

 If the compression strategy is changed, the next invocation of deflate will compress the input available so far with the old strategy (and may be flushed); the new strategy will take effect only after that invocation. 
Params:
  • strategy – the new compression strategy
Throws:
/**
     * Sets the compression strategy to the specified value.
     *
     * <p> If the compression strategy is changed, the next invocation
     * of {@code deflate} will compress the input available so far with
     * the old strategy (and may be flushed); the new strategy will take
     * effect only after that invocation.
     *
     * @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 compression level to the specified value.

 If the compression level is changed, the next invocation of deflate will compress the input available so far with the old level (and may be flushed); the new level will take effect only after that invocation. 
Params:
  • level – the new compression level (0-9)
Throws:
/**
     * Sets the compression level to the specified value.
     *
     * <p> If the compression level is changed, the next invocation
     * of {@code deflate} will compress the input available so far
     * with the old level (and may be flushed); the new level will
     * take effect only after that invocation.
     *
     * @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 no data remains in the input buffer. This can be used to determine if one of the setInput() methods should be called in order to provide more input. 
Returns:true if the input data buffer is empty and setInput()
should be called in order to provide more input
/**
     * Returns true if no data remains in the input buffer. This can
     * be used to determine if one of the {@code setInput()} methods 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() {
        synchronized (zsRef) {
            ByteBuffer input = this.input;
            return input == null ? inputLim == inputPos : ! input.hasRemaining();
        }
    }

    
When called, indicates that compression should end with the current
contents of the input buffer.

/**
     * 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.

Returns:true if the end of the compressed data output stream has
been reached
/**
     * 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 needsInput should be called in order to determine if more input data is required. 
This method uses NO_FLUSH as its compression flush mode. An invocation of this method of the form deflater.deflate(b, off, len) yields the same result as the invocation of deflater.deflate(b, off, len, Deflater.NO_FLUSH). 
Params:
  • output – the buffer for the compressed data
  • off – the start offset of the data
  • len – the maximum number of bytes of compressed data
Returns:the actual number of bytes of compressed data written to the
        output buffer
/**
     * 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 output 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[] output, int off, int len) {
        return deflate(output, 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 needsInput should be called in order to determine if more input data is required. 
This method uses NO_FLUSH as its compression flush mode. An invocation of this method of the form deflater.deflate(b) yields the same result as the invocation of deflater.deflate(b, 0, b.length, Deflater.NO_FLUSH). 
Params:
  • output – the buffer for the compressed data
Returns:the actual number of bytes of compressed data written to the
        output buffer
/**
     * 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 output the buffer for the compressed data
     * @return the actual number of bytes of compressed data written to the
     *         output buffer
     */
    public int deflate(byte[] output) {
        return deflate(output, 0, output.length, 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 needsInput should be called in order to determine if more input data is required. 
This method uses NO_FLUSH as its compression flush mode. An invocation of this method of the form deflater.deflate(output) yields the same result as the invocation of deflater.deflate(output, Deflater.NO_FLUSH). 
Params:
  • output – the buffer for the compressed data
Returns:the actual number of bytes of compressed data written to the
        output buffer
Since:11
/**
     * 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(output)}
     * yields the same result as the invocation of
     * {@code deflater.deflate(output, Deflater.NO_FLUSH)}.
     *
     * @param output the buffer for the compressed data
     * @return the actual number of bytes of compressed data written to the
     *         output buffer
     * @since 11
     */
    public int deflate(ByteBuffer output) {
        return deflate(output, NO_FLUSH);
    }

    
Compresses the input data and fills the specified buffer with compressed
data. Returns actual number of bytes of data compressed.

Compression flush mode is one of the following three modes:

    

  • 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 needsInput() should be called in order to determine if more input data is required. 
  • 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 needsInput() returns true after this invocation if enough output space is provided). Flushing with SYNC_FLUSH may degrade compression for some compression algorithms and so it should be used only when necessary. 
  • FULL_FLUSH: all pending output is flushed out as with 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 FULL_FLUSH too often can seriously degrade compression. 


In the case of FULL_FLUSH or SYNC_FLUSH, if the return value is len, the space available in output buffer b, this method should be invoked again with the same flush parameter and more output space. Make sure that len is greater than 6 to avoid flush marker (5 bytes) being repeatedly output to the output buffer every time this method is invoked. 
If the setInput(ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced by the number of bytes consumed by this operation. 
Params:
  • output – the buffer for the compressed data
  • off – the start offset of the data
  • len – the maximum number of bytes of compressed data
  • flush – the compression flush mode
Throws:
Returns:the actual number of bytes of compressed data written to
        the output buffer
Since:1.7
/**
     * 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. Make sure that
     * {@code len} is greater than 6 to avoid flush marker (5 bytes) being
     * repeatedly output to the output buffer every time this method is
     * invoked.
     *
     * <p>If the {@link #setInput(ByteBuffer)} method was called to provide a buffer
     * for input, the input buffer's position will be advanced by the number of bytes
     * consumed by this operation.
     *
     * @param output 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[] output, int off, int len, int flush) {
        if (off < 0 || len < 0 || off > output.length - len) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (flush != NO_FLUSH && flush != SYNC_FLUSH && flush != FULL_FLUSH) {
            throw new IllegalArgumentException();
        }
        synchronized (zsRef) {
            ensureOpen();

            ByteBuffer input = this.input;
            if (finish) {
                // disregard given flush mode in this case
                flush = FINISH;
            }
            int params;
            if (setParams) {
                // bit 0: true to set params
                // bit 1-2: strategy (0, 1, or 2)
                // bit 3-31: level (0..9 or -1)
                params = 1 | strategy << 1 | level << 3;
            } else {
                params = 0;
            }
            int inputPos;
            long result;
            if (input == null) {
                inputPos = this.inputPos;
                result = deflateBytesBytes(zsRef.address(),
                    inputArray, inputPos, inputLim - inputPos,
                    output, off, len,
                    flush, params);
            } else {
                inputPos = input.position();
                int inputRem = Math.max(input.limit() - inputPos, 0);
                if (input.isDirect()) {
                    try {
                        long inputAddress = ((DirectBuffer) input).address();
                        result = deflateBufferBytes(zsRef.address(),
                            inputAddress + inputPos, inputRem,
                            output, off, len,
                            flush, params);
                    } finally {
                        Reference.reachabilityFence(input);
                    }
                } else {
                    byte[] inputArray = ZipUtils.getBufferArray(input);
                    int inputOffset = ZipUtils.getBufferOffset(input);
                    result = deflateBytesBytes(zsRef.address(),
                        inputArray, inputOffset + inputPos, inputRem,
                        output, off, len,
                        flush, params);
                }
            }
            int read = (int) (result & 0x7fff_ffffL);
            int written = (int) (result >>> 31 & 0x7fff_ffffL);
            if ((result >>> 62 & 1) != 0) {
                finished = true;
            }
            if (params != 0 && (result >>> 63 & 1) == 0) {
                setParams = false;
            }
            if (input != null) {
                input.position(inputPos + read);
            } else {
                this.inputPos = inputPos + read;
            }
            bytesWritten += written;
            bytesRead += read;
            return written;
        }
    }

    
Compresses the input data and fills the specified buffer with compressed
data. Returns actual number of bytes of data compressed.

Compression flush mode is one of the following three modes:

    

  • 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 needsInput() should be called in order to determine if more input data is required. 
  • 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 needsInput() returns true after this invocation if enough output space is provided). Flushing with SYNC_FLUSH may degrade compression for some compression algorithms and so it should be used only when necessary. 
  • FULL_FLUSH: all pending output is flushed out as with 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 FULL_FLUSH too often can seriously degrade compression. 


In the case of FULL_FLUSH or SYNC_FLUSH, if the return value is equal to the remaining space of the buffer, this method should be invoked again with the same flush parameter and more output space. Make sure that the buffer has at least 6 bytes of remaining space to avoid the flush marker (5 bytes) being repeatedly output to the output buffer every time this method is invoked. 
On success, the position of the given output byte buffer will be advanced by as many bytes as were produced by the operation, which is equal to the number returned by this method. 
If the setInput(ByteBuffer) method was called to provide a buffer for input, the input buffer's position will be advanced by the number of bytes consumed by this operation. 
Params:
  • output – the buffer for the compressed data
  • flush – the compression flush mode
Throws:
Returns:the actual number of bytes of compressed data written to
        the output buffer
Since:11
/**
     * 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 equal to the {@linkplain ByteBuffer#remaining() remaining space}
     * of the buffer, this method should be invoked again with the same
     * {@code flush} parameter and more output space. Make sure that
     * the buffer has at least 6 bytes of remaining space to avoid the
     * flush marker (5 bytes) being repeatedly output to the output buffer
     * every time this method is invoked.
     *
     * <p>On success, the position of the given {@code output} byte buffer will be
     * advanced by as many bytes as were produced by the operation, which is equal
     * to the number returned by this method.
     *
     * <p>If the {@link #setInput(ByteBuffer)} method was called to provide a buffer
     * for input, the input buffer's position will be advanced by the number of bytes
     * consumed by this operation.
     *
     * @param output the buffer for the 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 11
     */
    public int deflate(ByteBuffer output, int flush) {
        if (output.isReadOnly()) {
            throw new ReadOnlyBufferException();
        }
        if (flush != NO_FLUSH && flush != SYNC_FLUSH && flush != FULL_FLUSH) {
            throw new IllegalArgumentException();
        }
        synchronized (zsRef) {
            ensureOpen();

            ByteBuffer input = this.input;
            if (finish) {
                // disregard given flush mode in this case
                flush = FINISH;
            }
            int params;
            if (setParams) {
                // bit 0: true to set params
                // bit 1-2: strategy (0, 1, or 2)
                // bit 3-31: level (0..9 or -1)
                params = 1 | strategy << 1 | level << 3;
            } else {
                params = 0;
            }
            int outputPos = output.position();
            int outputRem = Math.max(output.limit() - outputPos, 0);
            int inputPos;
            long result;
            if (input == null) {
                inputPos = this.inputPos;
                if (output.isDirect()) {
                    long outputAddress = ((DirectBuffer) output).address();
                    try {
                        result = deflateBytesBuffer(zsRef.address(),
                            inputArray, inputPos, inputLim - inputPos,
                            outputAddress + outputPos, outputRem,
                            flush, params);
                    } finally {
                        Reference.reachabilityFence(output);
                    }
                } else {
                    byte[] outputArray = ZipUtils.getBufferArray(output);
                    int outputOffset = ZipUtils.getBufferOffset(output);
                    result = deflateBytesBytes(zsRef.address(),
                        inputArray, inputPos, inputLim - inputPos,
                        outputArray, outputOffset + outputPos, outputRem,
                        flush, params);
                }
            } else {
                inputPos = input.position();
                int inputRem = Math.max(input.limit() - inputPos, 0);
                if (input.isDirect()) {
                    long inputAddress = ((DirectBuffer) input).address();
                    try {
                        if (output.isDirect()) {
                            long outputAddress = outputPos + ((DirectBuffer) output).address();
                            try {
                                result = deflateBufferBuffer(zsRef.address(),
                                    inputAddress + inputPos, inputRem,
                                    outputAddress, outputRem,
                                    flush, params);
                            } finally {
                                Reference.reachabilityFence(output);
                            }
                        } else {
                            byte[] outputArray = ZipUtils.getBufferArray(output);
                            int outputOffset = ZipUtils.getBufferOffset(output);
                            result = deflateBufferBytes(zsRef.address(),
                                inputAddress + inputPos, inputRem,
                                outputArray, outputOffset + outputPos, outputRem,
                                flush, params);
                        }
                    } finally {
                        Reference.reachabilityFence(input);
                    }
                } else {
                    byte[] inputArray = ZipUtils.getBufferArray(input);
                    int inputOffset = ZipUtils.getBufferOffset(input);
                    if (output.isDirect()) {
                        long outputAddress = ((DirectBuffer) output).address();
                        try {
                            result = deflateBytesBuffer(zsRef.address(),
                                inputArray, inputOffset + inputPos, inputRem,
                                outputAddress + outputPos, outputRem,
                                flush, params);
                        } finally {
                            Reference.reachabilityFence(output);
                        }
                    } else {
                        byte[] outputArray = ZipUtils.getBufferArray(output);
                        int outputOffset = ZipUtils.getBufferOffset(output);
                        result = deflateBytesBytes(zsRef.address(),
                            inputArray, inputOffset + inputPos, inputRem,
                            outputArray, outputOffset + outputPos, outputRem,
                            flush, params);
                    }
                }
            }
            int read = (int) (result & 0x7fff_ffffL);
            int written = (int) (result >>> 31 & 0x7fff_ffffL);
            if ((result >>> 62 & 1) != 0) {
                finished = true;
            }
            if (params != 0 && (result >>> 63 & 1) == 0) {
                setParams = false;
            }
            if (input != null) {
                input.position(inputPos + read);
            } else {
                this.inputPos = inputPos + read;
            }
            output.position(outputPos + written);
            bytesWritten += written;
            bytesRead += read;
            return written;
        }
    }

    
Returns the ADLER-32 value of the uncompressed data.

Returns:the ADLER-32 value of the uncompressed data
/**
     * 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.

Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesRead() method is now the preferred means of obtaining this information.


Returns:the total number of uncompressed bytes input so far
/**
     * 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.

Returns:the total (non-negative) number of uncompressed bytes input so far
Since:1.5
/**
     * Returns the total number of uncompressed bytes input so far.
     *
     * @return the total (non-negative) number of uncompressed bytes input so far
     * @since 1.5
     */
    public long getBytesRead() {
        synchronized (zsRef) {
            ensureOpen();
            return bytesRead;
        }
    }

    
Returns the total number of compressed bytes output so far.

Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesWritten() method is now the preferred means of obtaining this information.


Returns:the total number of compressed bytes output so far
/**
     * 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.

Returns:the total (non-negative) number of compressed bytes output so far
Since:1.5
/**
     * Returns the total number of compressed bytes output so far.
     *
     * @return the total (non-negative) number of compressed bytes output so far
     * @since 1.5
     */
    public long getBytesWritten() {
        synchronized (zsRef) {
            ensureOpen();
            return bytesWritten;
        }
    }

    
Resets deflater so that a new set of input data can be processed.
Keeps current compression level and strategy settings.

/**
     * 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) {
            ensureOpen();
            reset(zsRef.address());
            finish = false;
            finished = false;
            input = ZipUtils.defaultBuf;
            inputArray = null;
            bytesRead = bytesWritten = 0;
        }
    }

    
Closes the compressor and discards any unprocessed input.
This method should be called when the compressor is no longer
being used. Once this method is called, the behavior of the
Deflater object is undefined.

/**
     * Closes the compressor and discards any unprocessed input.
     *
     * This method should be called when the compressor is no longer
     * being used. Once this method is called, the behavior of the
     * Deflater object is undefined.
     */
    public void end() {
        synchronized (zsRef) {
            zsRef.clean();
            input = ZipUtils.defaultBuf;
        }
    }

    private void ensureOpen() {
        assert Thread.holdsLock(zsRef);
        if (zsRef.address() == 0)
            throw new NullPointerException("Deflater has been closed");
    }

    private static native long init(int level, int strategy, boolean nowrap);
    private static native void setDictionary(long addr, byte[] b, int off,
                                             int len);
    private static native void setDictionaryBuffer(long addr, long bufAddress, int len);
    private native long deflateBytesBytes(long addr,
        byte[] inputArray, int inputOff, int inputLen,
        byte[] outputArray, int outputOff, int outputLen,
        int flush, int params);
    private native long deflateBytesBuffer(long addr,
        byte[] inputArray, int inputOff, int inputLen,
        long outputAddress, int outputLen,
        int flush, int params);
    private native long deflateBufferBytes(long addr,
        long inputAddress, int inputLen,
        byte[] outputArray, int outputOff, int outputLen,
        int flush, int params);
    private native long deflateBufferBuffer(long addr,
        long inputAddress, int inputLen,
        long outputAddress, int outputLen,
        int flush, int params);
    private static native int getAdler(long addr);
    private static native void reset(long addr);
    private static native void end(long addr);

    
A reference to the native zlib's z_stream structure. It also
serves as the "cleaner" to clean up the native resource when
the Deflater is ended, closed or cleaned.

/**
     * A reference to the native zlib's z_stream structure. It also
     * serves as the "cleaner" to clean up the native resource when
     * the Deflater is ended, closed or cleaned.
     */
    static class DeflaterZStreamRef implements Runnable {

        private long address;
        private final Cleanable cleanable;

        private DeflaterZStreamRef(Deflater owner, long addr) {
            this.cleanable = (owner != null) ? CleanerFactory.cleaner().register(owner, this) : null;
            this.address = addr;
        }

        long address() {
            return address;
        }

        void clean() {
            cleanable.clean();
        }

        public synchronized void run() {
            long addr = address;
            address = 0;
            if (addr != 0) {
                end(addr);
            }
        }

    }
}