hadoop FixedLengthRecordReader 源码
haddop FixedLengthRecordReader 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/FixedLengthRecordReader.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.mapred;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.LongWritable;
/**
* A reader to read fixed length records from a split. Record offset is
* returned as key and the record as bytes is returned in value.
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class FixedLengthRecordReader
implements RecordReader<LongWritable, BytesWritable> {
private int recordLength;
// Make use of the new API implementation to avoid code duplication.
private org.apache.hadoop.mapreduce.lib.input.FixedLengthRecordReader reader;
public FixedLengthRecordReader(Configuration job, FileSplit split,
int recordLength) throws IOException {
this.recordLength = recordLength;
reader = new org.apache.hadoop.mapreduce.lib.input.FixedLengthRecordReader(
recordLength);
reader.initialize(job, split.getStart(), split.getLength(),
split.getPath());
}
@Override
public LongWritable createKey() {
return new LongWritable();
}
@Override
public BytesWritable createValue() {
return new BytesWritable(new byte[recordLength]);
}
@Override
public synchronized boolean next(LongWritable key, BytesWritable value)
throws IOException {
boolean dataRead = reader.nextKeyValue();
if (dataRead) {
LongWritable newKey = reader.getCurrentKey();
BytesWritable newValue = reader.getCurrentValue();
key.set(newKey.get());
value.set(newValue);
}
return dataRead;
}
@Override
public float getProgress() throws IOException {
return reader.getProgress();
}
@Override
public synchronized long getPos() throws IOException {
return reader.getPos();
}
@Override
public void close() throws IOException {
reader.close();
}
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦