Java tutorial
/** * 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.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.compress.CompressionCodec; import org.apache.hadoop.io.compress.CompressionCodecFactory; import org.apache.hadoop.io.compress.SplittableCompressionCodec; /** * An {@link InputFormat} for plain text files. Files are broken into lines. * Either linefeed or carriage-return are used to signal end of line. Each line * is divided into key and value parts by a separator byte. If no such a byte * exists, the key will be the entire line and value will be empty. */ @InterfaceAudience.Public @InterfaceStability.Stable public class KeyValueTextInputFormat extends FileInputFormat<Text, Text> implements JobConfigurable { private CompressionCodecFactory compressionCodecs = null; public void configure(JobConf conf) { compressionCodecs = new CompressionCodecFactory(conf); } protected boolean isSplitable(FileSystem fs, Path file) { final CompressionCodec codec = compressionCodecs.getCodec(file); if (null == codec) { return true; } return codec instanceof SplittableCompressionCodec; } public RecordReader<Text, Text> getRecordReader(InputSplit genericSplit, JobConf job, Reporter reporter) throws IOException { reporter.setStatus(genericSplit.toString()); return new KeyValueLineRecordReader(job, (FileSplit) genericSplit); } }