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Java impmenentation of compression algorithm Snappy from Google. This is a Avast a.s. fork of
http://code.google.com/p/jsnappy/ , it adds bytecompressor layer compatibility.
The newest version!
/*
* Copyright 2011 Tor-Einar Jarnbjo
*
* Licensed 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 de.jarnbjo.jsnappy;
/**
* This class provide utility methods for compressing
* data blocks using the Snappy algorithm.
*
* @author Tor-Einar Jarnbjo
* @since 1.0
*/
public class SnappyCompressor {
/**
* Default effort used for compression
*/
public static final int DEFAULT_EFFORT = 1;
private SnappyCompressor() {
}
/**
* Equivalent to compress(in, 0, in.length, null).
* @param in data to be compressed
* @return compressed data block
*/
public static Buffer compress(byte[] in) {
return compress(in, 0, in.length, null);
}
/**
* Equivalent to compress(in, 0, in.length, out).
* @param in data to be compressed
* @param out Buffer for compressed data block
* @return reference to out
*/
public static Buffer compress(byte[] in, Buffer out) {
return compress(in, 0, in.length, out);
}
/**
* Equivalent to compress(in, offset, length, null).
* @param in data to be compressed
* @param offset offset in in, on which encoding is started
* @param length number of bytes read from the input block
* @return compressed data block
*/
public static Buffer compress(byte[] in, int offset, int length) {
return compress(in, offset, length, null);
}
/**
* Equivalent to compress(in.getData(), 0, in.getLength(), null).
* @param in data to be compressed
* @return compressed data block
*/
public static Buffer compress(Buffer in) {
return compress(in.getData(), 0, in.getLength(), null);
}
/**
* Equivalent to compress(in.getData(), 0, in.getLength(), out).
* @param in data to be compressed
* @param out buffer for decompressed data block
* @return reference to out
*/
public static Buffer compress(Buffer in, Buffer out) {
return compress(in.getData(), 0, in.getLength(), out);
}
/**
* Equivalent to compress(in.getData(), 0, in.getLength(), out, DEFAULT_EFFORT).
* @param in input data
* @param offset offset into input data
* @param length length of input data
* @param out output buffer or null (new buffer will be allocated)
* @return reference to out
*/
public static Buffer compress(byte[] in, int offset, int length, Buffer out) {
return compress(in, offset, length, out, DEFAULT_EFFORT);
}
/**
*
* Compress the data contained in in from offset
* and length bytes. If an output buffer is provided, the buffer
* is reused for the compressed data. If the buffer is too small, its capacity
* is expanded to fit the result. If a null argument is passed,
* a new buffer is allocated.
*
*
*
* The compression effort can be set from 1 (fastest, less compression) to 100 (slowest, highest compression).
*
*
* @param in input data
* @param offset offset into input data
* @param length length of input data
* @param out output buffer or null (new buffer will be allocated)
* @param effort compression effort
* @return
*/
public static Buffer compress(byte[] in, int offset, int length, Buffer out, int effort) {
if(effort < 1 || effort > 100) {
throw new IllegalArgumentException("Compression effort must be an integer from 0 (fastest, less compression) to 100 (slowest, highest compression)");
}
if(effort < 30) {
return TableBasedCompressor.compress(in, offset, length, out);
}
else if(effort < 70) {
return MapBasedCompressor.compress(in, offset, length, out, true);
}
else {
return MapBasedCompressor.compress(in, offset, length, out, false);
}
}
}