/* |
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* Copyright (c) 1996, 2013, 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 long bytesRead; |
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private long bytesWritten; |
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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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int thisLen = this.len; |
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int n = inflateBytes(zsRef.address(), b, off, len); |
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bytesWritten += n; |
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bytesRead += (thisLen - this.len); |
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return n; |
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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. |
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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 bytesRead; |
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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. |
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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 bytesWritten; |
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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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bytesRead = bytesWritten = 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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boolean ended() { |
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synchronized (zsRef) { |
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return zsRef.address() == 0; |
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} |
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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 void reset(long addr); |
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private native static void end(long addr); |
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} |