| /* DeflateTransformer.java -- |
| Copyright (C) 2003, 2006 Free Software Foundation, Inc. |
| |
| This file is a part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or (at |
| your option) any later version. |
| |
| GNU Classpath 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 for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 |
| USA |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.javax.crypto.assembly; |
| |
| import java.util.Map; |
| import java.util.zip.DataFormatException; |
| import java.util.zip.Deflater; |
| import java.util.zip.Inflater; |
| |
| /** |
| * A {@link Transformer} Adapter allowing inclusion of a DEFLATE compression |
| * algorithm in an {@link Assembly} chain. The {@link Direction#FORWARD} |
| * transformation is a compression (deflate) of input data, while the |
| * {@link Direction#REVERSED} one is a decompression (inflate) that restores the |
| * original data. |
| * <p> |
| * This {@link Transformer} uses a {@link Deflater} instance to carry on the |
| * compression, and an {@link Inflater} to do the decompression. |
| * <p> |
| * When using such a {@link Transformer}, in an {@link Assembly}, there must |
| * be at least one element behind this instance in the constructed chain; |
| * otherwise, a {@link TransformerException} is thrown at initialisation time. |
| */ |
| class DeflateTransformer |
| extends Transformer |
| { |
| private Deflater compressor; |
| |
| private Inflater decompressor; |
| |
| private int outputBlockSize = 512; // default zlib buffer size |
| |
| private byte[] zlibBuffer; |
| |
| DeflateTransformer() |
| { |
| super(); |
| |
| } |
| |
| void initDelegate(Map attributes) throws TransformerException |
| { |
| if (tail == null) |
| { |
| IllegalStateException cause = new IllegalStateException( |
| "Compression transformer missing its tail!"); |
| throw new TransformerException("initDelegate()", cause); |
| } |
| outputBlockSize = tail.currentBlockSize(); |
| zlibBuffer = new byte[outputBlockSize]; |
| Direction flow = (Direction) attributes.get(DIRECTION); |
| if (flow == Direction.FORWARD) |
| compressor = new Deflater(); |
| else |
| decompressor = new Inflater(); |
| } |
| |
| int delegateBlockSize() |
| { |
| return 1; |
| } |
| |
| void resetDelegate() |
| { |
| compressor = null; |
| decompressor = null; |
| outputBlockSize = 1; |
| zlibBuffer = null; |
| } |
| |
| byte[] updateDelegate(byte[] in, int offset, int length) |
| throws TransformerException |
| { |
| byte[] result; |
| if (wired == Direction.FORWARD) |
| { |
| compressor.setInput(in, offset, length); |
| while (! compressor.needsInput()) |
| compress(); |
| } |
| else // decompression: inflate first and then update tail |
| decompress(in, offset, length); |
| result = inBuffer.toByteArray(); |
| inBuffer.reset(); |
| return result; |
| } |
| |
| byte[] lastUpdateDelegate() throws TransformerException |
| { |
| // process multiples of blocksize as much as possible |
| if (wired == Direction.FORWARD) // compressing |
| { |
| if (! compressor.finished()) |
| { |
| compressor.finish(); |
| while (! compressor.finished()) |
| compress(); |
| } |
| } |
| else // decompressing |
| { |
| if (! decompressor.finished()) |
| { |
| IllegalStateException cause = new IllegalStateException( |
| "Compression transformer, after last update, must be finished " |
| + "but isn't"); |
| throw new TransformerException("lastUpdateDelegate()", cause); |
| } |
| } |
| byte[] result = inBuffer.toByteArray(); |
| inBuffer.reset(); |
| return result; |
| } |
| |
| private void compress() |
| { |
| int len = compressor.deflate(zlibBuffer); |
| if (len > 0) |
| inBuffer.write(zlibBuffer, 0, len); |
| } |
| |
| private void decompress(byte[] in, int offset, int length) |
| throws TransformerException |
| { |
| decompressor.setInput(in, offset, length); |
| int len = 1; |
| while (len > 0) |
| { |
| try |
| { |
| len = decompressor.inflate(zlibBuffer); |
| } |
| catch (DataFormatException x) |
| { |
| throw new TransformerException("decompress()", x); |
| } |
| if (len > 0) |
| inBuffer.write(zlibBuffer, 0, len); |
| } |
| } |
| } |