hadoop RawBytesOutputReader 源码
haddop RawBytesOutputReader 代码
文件路径：/hadoop-tools/hadoop-streaming/src/main/java/org/apache/hadoop/streaming/io/RawBytesOutputReader.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.streaming.io;
import java.io.DataInput;
import java.io.EOFException;
import java.io.IOException;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.streaming.PipeMapRed;
/**
* OutputReader that reads the client's output as raw bytes.
*/
public class RawBytesOutputReader
extends OutputReader<BytesWritable, BytesWritable> {
private DataInput clientIn;
private byte[] bytes;
private BytesWritable key;
private BytesWritable value;
@Override
public void initialize(PipeMapRed pipeMapRed) throws IOException {
super.initialize(pipeMapRed);
clientIn = pipeMapRed.getClientInput();
key = new BytesWritable();
value = new BytesWritable();
}
@Override
public boolean readKeyValue() throws IOException {
int length = readLength();
if (length < 0) {
return false;
}
key.set(readBytes(length), 0, length);
length = readLength();
value.set(readBytes(length), 0, length);
return true;
}
@Override
public BytesWritable getCurrentKey() throws IOException {
return key;
}
@Override
public BytesWritable getCurrentValue() throws IOException {
return value;
}
@Override
public String getLastOutput() {
if (bytes != null) {
return new BytesWritable(bytes).toString();
} else {
return null;
}
}
private int readLength() throws IOException {
try {
return clientIn.readInt();
} catch (EOFException eof) {
return -1;
}
}
private byte[] readBytes(int length) throws IOException {
bytes = new byte[length];
clientIn.readFully(bytes);
return bytes;
}
}
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