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/*
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* Copyright (c) 1996, 2009, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util.zip;
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/**
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* This class provides support for general purpose decompression using the
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* popular ZLIB compression library. The ZLIB compression library was
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* initially developed as part of the PNG graphics standard and is not
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* protected by patents. It is fully described in the specifications at
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* the <a href="package-summary.html#package_description">java.util.zip
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* package description</a>.
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*
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* <p>The following code fragment demonstrates a trivial compression
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* and decompression of a string using <tt>Deflater</tt> and
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* <tt>Inflater</tt>.
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*
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* <blockquote><pre>
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* try {
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* // Encode a String into bytes
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* String inputString = "blahblahblah\u20AC\u20AC";
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* byte[] input = inputString.getBytes("UTF-8");
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*
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* // Compress the bytes
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* byte[] output = new byte[100];
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* Deflater compresser = new Deflater();
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* compresser.setInput(input);
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* compresser.finish();
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* int compressedDataLength = compresser.deflate(output);
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*
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* // Decompress the bytes
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* Inflater decompresser = new Inflater();
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* decompresser.setInput(output, 0, compressedDataLength);
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* byte[] result = new byte[100];
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* int resultLength = decompresser.inflate(result);
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* decompresser.end();
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*
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* // Decode the bytes into a String
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* String outputString = new String(result, 0, resultLength, "UTF-8");
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* } catch(java.io.UnsupportedEncodingException ex) {
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* // handle
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* } catch (java.util.zip.DataFormatException ex) {
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* // handle
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* }
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* </pre></blockquote>
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*
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* @see Deflater
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* @author David Connelly
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*
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*/
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public
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class Inflater {
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private final ZStreamRef zsRef;
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private byte[] buf = defaultBuf;
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private int off, len;
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private boolean finished;
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private boolean needDict;
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private static final byte[] defaultBuf = new byte[0];
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static {
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/* Zip library is loaded from System.initializeSystemClass */
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initIDs();
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}
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/**
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* Creates a new decompressor. If the parameter 'nowrap' is true then
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* the ZLIB header and checksum fields will not be used. This provides
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* compatibility with the compression format used by both GZIP and PKZIP.
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* <p>
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* Note: When using the 'nowrap' option it is also necessary to provide
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* an extra "dummy" byte as input. This is required by the ZLIB native
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* library in order to support certain optimizations.
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*
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* @param nowrap if true then support GZIP compatible compression
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*/
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public Inflater(boolean nowrap) {
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zsRef = new ZStreamRef(init(nowrap));
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}
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/**
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* Creates a new decompressor.
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*/
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public Inflater() {
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this(false);
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}
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/**
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* Sets input data for decompression. Should be called whenever
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* needsInput() returns true indicating that more input data is
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* required.
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* @param b the input data bytes
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* @param off the start offset of the input data
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* @param len the length of the input data
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* @see Inflater#needsInput
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*/
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public void setInput(byte[] b, int off, int len) {
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if (b == null) {
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throw new NullPointerException();
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}
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if (off < 0 || len < 0 || off > b.length - len) {
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throw new ArrayIndexOutOfBoundsException();
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}
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synchronized (zsRef) {
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this.buf = b;
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this.off = off;
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this.len = len;
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}
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}
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/**
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* Sets input data for decompression. Should be called whenever
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* needsInput() returns true indicating that more input data is
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* required.
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* @param b the input data bytes
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* @see Inflater#needsInput
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*/
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public void setInput(byte[] b) {
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setInput(b, 0, b.length);
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}
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/**
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* Sets the preset dictionary to the given array of bytes. Should be
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* called when inflate() returns 0 and needsDictionary() returns true
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* indicating that a preset dictionary is required. The method getAdler()
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* can be used to get the Adler-32 value of the dictionary needed.
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* @param b the dictionary data bytes
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* @param off the start offset of the data
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* @param len the length of the data
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* @see Inflater#needsDictionary
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* @see Inflater#getAdler
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*/
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public void setDictionary(byte[] b, int off, int len) {
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if (b == null) {
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throw new NullPointerException();
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}
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if (off < 0 || len < 0 || off > b.length - len) {
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throw new ArrayIndexOutOfBoundsException();
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}
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synchronized (zsRef) {
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ensureOpen();
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setDictionary(zsRef.address(), b, off, len);
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needDict = false;
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}
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}
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/**
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* Sets the preset dictionary to the given array of bytes. Should be
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* called when inflate() returns 0 and needsDictionary() returns true
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* indicating that a preset dictionary is required. The method getAdler()
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* can be used to get the Adler-32 value of the dictionary needed.
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* @param b the dictionary data bytes
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* @see Inflater#needsDictionary
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* @see Inflater#getAdler
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*/
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public void setDictionary(byte[] b) {
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setDictionary(b, 0, b.length);
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}
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/**
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* Returns the total number of bytes remaining in the input buffer.
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* This can be used to find out what bytes still remain in the input
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* buffer after decompression has finished.
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* @return the total number of bytes remaining in the input buffer
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*/
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public int getRemaining() {
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synchronized (zsRef) {
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return len;
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}
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}
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/**
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* Returns true if no data remains in the input buffer. This can
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* be used to determine if #setInput should be called in order
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* to provide more input.
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* @return true if no data remains in the input buffer
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*/
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public boolean needsInput() {
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synchronized (zsRef) {
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return len <= 0;
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}
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}
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/**
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* Returns true if a preset dictionary is needed for decompression.
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* @return true if a preset dictionary is needed for decompression
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* @see Inflater#setDictionary
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*/
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public boolean needsDictionary() {
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synchronized (zsRef) {
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return needDict;
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}
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}
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/**
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* Returns true if the end of the compressed data stream has been
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* reached.
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* @return true if the end of the compressed data stream has been
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* reached
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*/
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public boolean finished() {
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synchronized (zsRef) {
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return finished;
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}
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}
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/**
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* Uncompresses bytes into specified buffer. Returns actual number
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* of bytes uncompressed. A return value of 0 indicates that
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* needsInput() or needsDictionary() should be called in order to
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* determine if more input data or a preset dictionary is required.
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* In the latter case, getAdler() can be used to get the Adler-32
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* value of the dictionary required.
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* @param b the buffer for the uncompressed data
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* @param off the start offset of the data
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* @param len the maximum number of uncompressed bytes
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* @return the actual number of uncompressed bytes
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* @exception DataFormatException if the compressed data format is invalid
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* @see Inflater#needsInput
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* @see Inflater#needsDictionary
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*/
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public int inflate(byte[] b, int off, int len)
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throws DataFormatException
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{
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if (b == null) {
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throw new NullPointerException();
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}
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if (off < 0 || len < 0 || off > b.length - len) {
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throw new ArrayIndexOutOfBoundsException();
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}
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synchronized (zsRef) {
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ensureOpen();
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return inflateBytes(zsRef.address(), b, off, len);
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}
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}
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/**
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* Uncompresses bytes into specified buffer. Returns actual number
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* of bytes uncompressed. A return value of 0 indicates that
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* needsInput() or needsDictionary() should be called in order to
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* determine if more input data or a preset dictionary is required.
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* In the latter case, getAdler() can be used to get the Adler-32
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* value of the dictionary required.
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* @param b the buffer for the uncompressed data
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* @return the actual number of uncompressed bytes
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* @exception DataFormatException if the compressed data format is invalid
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* @see Inflater#needsInput
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* @see Inflater#needsDictionary
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*/
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public int inflate(byte[] b) throws DataFormatException {
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return inflate(b, 0, b.length);
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}
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/**
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* Returns the ADLER-32 value of the uncompressed data.
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* @return the ADLER-32 value of the uncompressed data
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*/
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public int getAdler() {
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synchronized (zsRef) {
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ensureOpen();
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return getAdler(zsRef.address());
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}
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}
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/**
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* Returns the total number of compressed bytes input so far.
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*
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* <p>Since the number of bytes may be greater than
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* Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
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* the preferred means of obtaining this information.</p>
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*
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* @return the total number of compressed bytes input so far
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*/
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public int getTotalIn() {
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return (int) getBytesRead();
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}
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/**
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* Returns the total number of compressed bytes input so far.</p>
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*
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* @return the total (non-negative) number of compressed bytes input so far
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* @since 1.5
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*/
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public long getBytesRead() {
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synchronized (zsRef) {
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ensureOpen();
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return getBytesRead(zsRef.address());
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}
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}
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/**
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* Returns the total number of uncompressed bytes output so far.
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*
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* <p>Since the number of bytes may be greater than
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* Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
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* the preferred means of obtaining this information.</p>
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*
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* @return the total number of uncompressed bytes output so far
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*/
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public int getTotalOut() {
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return (int) getBytesWritten();
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}
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/**
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* Returns the total number of uncompressed bytes output so far.</p>
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*
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* @return the total (non-negative) number of uncompressed bytes output so far
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* @since 1.5
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*/
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public long getBytesWritten() {
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synchronized (zsRef) {
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ensureOpen();
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return getBytesWritten(zsRef.address());
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}
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}
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/**
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* Resets inflater so that a new set of input data can be processed.
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*/
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public void reset() {
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synchronized (zsRef) {
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ensureOpen();
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reset(zsRef.address());
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buf = defaultBuf;
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finished = false;
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needDict = false;
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off = len = 0;
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}
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}
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/**
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* Closes the decompressor and discards any unprocessed input.
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* This method should be called when the decompressor is no longer
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* being used, but will also be called automatically by the finalize()
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* method. Once this method is called, the behavior of the Inflater
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* object is undefined.
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*/
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public void end() {
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synchronized (zsRef) {
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long addr = zsRef.address();
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zsRef.clear();
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if (addr != 0) {
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end(addr);
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buf = null;
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}
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}
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}
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/**
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* Closes the decompressor when garbage is collected.
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*/
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protected void finalize() {
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end();
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}
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private void ensureOpen () {
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assert Thread.holdsLock(zsRef);
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if (zsRef.address() == 0)
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throw new NullPointerException("Inflater has been closed");
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}
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private native static void initIDs();
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private native static long init(boolean nowrap);
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private native static void setDictionary(long addr, byte[] b, int off,
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int len);
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private native int inflateBytes(long addr, byte[] b, int off, int len)
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throws DataFormatException;
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private native static int getAdler(long addr);
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private native static long getBytesRead(long addr);
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private native static long getBytesWritten(long addr);
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private native static void reset(long addr);
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private native static void end(long addr);
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}
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