001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.mapreduce.lib.input;
020    
021    import java.io.IOException;
022    
023    import org.apache.hadoop.classification.InterfaceAudience;
024    import org.apache.hadoop.classification.InterfaceStability;
025    import org.apache.hadoop.fs.Path;
026    import org.apache.hadoop.io.Text;
027    import org.apache.hadoop.io.compress.CompressionCodec;
028    import org.apache.hadoop.io.compress.CompressionCodecFactory;
029    import org.apache.hadoop.io.compress.SplittableCompressionCodec;
030    import org.apache.hadoop.mapreduce.InputFormat;
031    import org.apache.hadoop.mapreduce.InputSplit;
032    import org.apache.hadoop.mapreduce.JobContext;
033    import org.apache.hadoop.mapreduce.RecordReader;
034    import org.apache.hadoop.mapreduce.TaskAttemptContext;
035    
036    /**
037     * An {@link InputFormat} for plain text files. Files are broken into lines.
038     * Either line feed or carriage-return are used to signal end of line. 
039     * Each line is divided into key and value parts by a separator byte. If no
040     * such a byte exists, the key will be the entire line and value will be empty.
041     * The separator byte can be specified in config file under the attribute name
042     * mapreduce.input.keyvaluelinerecordreader.key.value.separator. The default
043     * is the tab character ('\t').
044     */
045    @InterfaceAudience.Public
046    @InterfaceStability.Stable
047    public class KeyValueTextInputFormat extends FileInputFormat<Text, Text> {
048    
049      @Override
050      protected boolean isSplitable(JobContext context, Path file) {
051        final CompressionCodec codec =
052          new CompressionCodecFactory(context.getConfiguration()).getCodec(file);
053        if (null == codec) {
054          return true;
055        }
056        return codec instanceof SplittableCompressionCodec;
057      }
058    
059      public RecordReader<Text, Text> createRecordReader(InputSplit genericSplit,
060          TaskAttemptContext context) throws IOException {
061        
062        context.setStatus(genericSplit.toString());
063        return new KeyValueLineRecordReader(context.getConfiguration());
064      }
065    
066    }