/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.mina.filter.support;
import java.io.IOException;
import org.apache.mina.common.ByteBuffer;
import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;
/**
* A helper class for interfacing with the JZlib library. This class acts both
* as a compressor and decompressor, but only as one at a time. The only
* flush method supported is <tt>Z_SYNC_FLUSH</tt> also known as <tt>Z_PARTIAL_FLUSH</tt>
*
* @author The Apache Directory Project (mina-dev@directory.apache.org)
* @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (Fri, 13 Jul 2007) $
*/
public class Zlib {
public static final int COMPRESSION_MAX = JZlib.Z_BEST_COMPRESSION;
public static final int COMPRESSION_MIN = JZlib.Z_BEST_SPEED;
public static final int COMPRESSION_NONE = JZlib.Z_NO_COMPRESSION;
public static final int COMPRESSION_DEFAULT = JZlib.Z_DEFAULT_COMPRESSION;
public static final int MODE_DEFLATER = 1;
public static final int MODE_INFLATER = 2;
private int compressionLevel;
private ZStream zStream = null;
private int mode = -1;
/**
* @param compressionLevel the level of compression that should be used
* @param mode the mode in which the instance will operate. Can be either
* of <tt>MODE_DEFLATER</tt> or <tt>MODE_INFLATER</tt>
*/
public Zlib(int compressionLevel, int mode) {
switch (compressionLevel) {
case COMPRESSION_MAX:
case COMPRESSION_MIN:
case COMPRESSION_NONE:
case COMPRESSION_DEFAULT:
this.compressionLevel = compressionLevel;
break;
default:
throw new IllegalArgumentException(
"invalid compression level specified");
}
// create a new instance of ZStream. This will be done only once.
zStream = new ZStream();
switch (mode) {
case MODE_DEFLATER:
zStream.deflateInit(this.compressionLevel);
break;
case MODE_INFLATER:
zStream.inflateInit();
break;
default:
throw new IllegalArgumentException("invalid mode specified");
}
this.mode = mode;
}
/**
* @param inBuffer the {@link ByteBuffer} to be decompressed. The contents
* of the buffer are transferred into a local byte array and the buffer is
* flipped and returned intact.
* @return the decompressed data. If not passed to the MINA methods that
* release the buffer automatically, the buffer has to be manually released
* @throws IOException if the decompression of the data failed for some reason.
*/
public ByteBuffer inflate(ByteBuffer inBuffer) throws IOException {
if (mode == MODE_DEFLATER) {
throw new IllegalStateException("not initialized as INFLATER");
}
byte[] inBytes = new byte[inBuffer.limit()];
inBuffer.get(inBytes).flip();
byte[] outBytes = new byte[inBytes.length * 2];
ByteBuffer outBuffer = ByteBuffer.allocate(outBytes.length);
outBuffer.setAutoExpand(true);
zStream.next_in = inBytes;
zStream.next_in_index = 0;
zStream.avail_in = inBytes.length;
zStream.next_out = outBytes;
zStream.next_out_index = 0;
zStream.avail_out = outBytes.length;
int retval = 0;
do {
retval = zStream.inflate(JZlib.Z_SYNC_FLUSH);
switch (retval) {
case JZlib.Z_OK:
// completed decompression, lets copy data and get out
case JZlib.Z_BUF_ERROR:
// need more space for output. store current output and get more
outBuffer.put(outBytes, 0, zStream.next_out_index);
zStream.next_out_index = 0;
zStream.avail_out = outBytes.length;
break;
default:
// unknown error
outBuffer.release();
outBuffer = null;
if (zStream.msg == null)
throw new IOException("Unknown error. Error code : "
+ retval);
else
throw new IOException("Unknown error. Error code : "
+ retval + " and message : " + zStream.msg);
}
} while (zStream.avail_in > 0);
return outBuffer.flip();
}
/**
* @param inBuffer the buffer to be compressed. The contents are transferred
* into a local byte array and the buffer is flipped and returned intact.
* @return the buffer with the compressed data. If not passed to any of the
* MINA methods that automatically release the buffer, the buffer has to be
* released manually.
* @throws IOException if the compression of teh buffer failed for some reason
*/
public ByteBuffer deflate(ByteBuffer inBuffer) throws IOException {
if (mode == MODE_INFLATER) {
throw new IllegalStateException("not initialized as DEFLATER");
}
byte[] inBytes = new byte[inBuffer.limit()];
inBuffer.get(inBytes).flip();
// according to spec, destination buffer should be 0.1% larger
// than source length plus 12 bytes. We add a single byte to safeguard
// against rounds that round down to the smaller value
int outLen = (int) Math.round(inBytes.length * 1.001) + 1 + 12;
byte[] outBytes = new byte[outLen];
zStream.next_in = inBytes;
zStream.next_in_index = 0;
zStream.avail_in = inBytes.length;
zStream.next_out = outBytes;
zStream.next_out_index = 0;
zStream.avail_out = outBytes.length;
int retval = zStream.deflate(JZlib.Z_SYNC_FLUSH);
if (retval != JZlib.Z_OK) {
outBytes = null;
inBytes = null;
throw new IOException("Compression failed with return value : "
+ retval);
}
ByteBuffer outBuf = ByteBuffer
.wrap(outBytes, 0, zStream.next_out_index);
return outBuf;
}
/**
* Cleans up the resources used by the compression library.
*/
public void cleanUp() {
if (zStream != null)
zStream.free();
}
}