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.mapred.lib; 020 021 import java.io.IOException; 022 import java.util.StringTokenizer; 023 024 import org.apache.hadoop.classification.InterfaceAudience; 025 import org.apache.hadoop.classification.InterfaceStability; 026 import org.apache.hadoop.io.LongWritable; 027 import org.apache.hadoop.io.Text; 028 import org.apache.hadoop.mapred.MapReduceBase; 029 import org.apache.hadoop.mapred.Mapper; 030 import org.apache.hadoop.mapred.OutputCollector; 031 import org.apache.hadoop.mapred.Reporter; 032 033 034 /** 035 * A {@link Mapper} that maps text values into <token,freq> pairs. Uses 036 * {@link StringTokenizer} to break text into tokens. 037 */ 038 @InterfaceAudience.Public 039 @InterfaceStability.Stable 040 public class TokenCountMapper<K> extends MapReduceBase 041 implements Mapper<K, Text, Text, LongWritable> { 042 043 public void map(K key, Text value, 044 OutputCollector<Text, LongWritable> output, 045 Reporter reporter) 046 throws IOException { 047 // get input text 048 String text = value.toString(); // value is line of text 049 050 // tokenize the value 051 StringTokenizer st = new StringTokenizer(text); 052 while (st.hasMoreTokens()) { 053 // output <token,1> pairs 054 output.collect(new Text(st.nextToken()), new LongWritable(1)); 055 } 056 } 057 058 }