hadoop BuiltInZlibDeflater 源码
haddop BuiltInZlibDeflater 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInZlibDeflater.java
/*
* 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.hadoop.io.compress.zlib;
import java.io.IOException;
import java.util.zip.Deflater;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.compress.Compressor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A wrapper around java.util.zip.Deflater to make it conform
* to org.apache.hadoop.io.compress.Compressor interface.
*
*/
public class BuiltInZlibDeflater extends Deflater implements Compressor {
private static final Logger LOG =
LoggerFactory.getLogger(BuiltInZlibDeflater.class);
public BuiltInZlibDeflater(int level, boolean nowrap) {
super(level, nowrap);
}
public BuiltInZlibDeflater(int level) {
super(level);
}
public BuiltInZlibDeflater() {
super();
}
@Override
public synchronized int compress(byte[] b, int off, int len)
throws IOException {
return super.deflate(b, off, len);
}
/**
* reinit the compressor with the given configuration. It will reset the
* compressor's compression level and compression strategy. Different from
* <tt>ZlibCompressor</tt>, <tt>BuiltInZlibDeflater</tt> only support three
* kind of compression strategy: FILTERED, HUFFMAN_ONLY and DEFAULT_STRATEGY.
* It will use DEFAULT_STRATEGY as default if the configured compression
* strategy is not supported.
*/
@Override
public void reinit(Configuration conf) {
reset();
if (conf == null) {
return;
}
setLevel(ZlibFactory.getCompressionLevel(conf).compressionLevel());
final ZlibCompressor.CompressionStrategy strategy =
ZlibFactory.getCompressionStrategy(conf);
try {
setStrategy(strategy.compressionStrategy());
} catch (IllegalArgumentException ill) {
LOG.warn(strategy + " not supported by BuiltInZlibDeflater.");
setStrategy(DEFAULT_STRATEGY);
}
if(LOG.isDebugEnabled()) {
LOG.debug("Reinit compressor with new compression configuration");
}
}
}
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