com.igalia.wordcount.WordCount.java Source code

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Here is the source code for com.igalia.wordcount.WordCount.java

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/*
 * Copyright (C) 2012 Igalia, S.L.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.igalia.wordcount;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;

/**
 * 
 * @author Diego Pino Garca <dpino@igalia.com>
 * 
 * Canonical implementation at http://wiki.apache.org/hadoop/WordCount
 *
 */
public class WordCount extends Configured implements Tool {

    public static class MapClass extends Mapper<Object, Text, Text, IntWritable> {

        private static final IntWritable ONE = new IntWritable(1);
        private Text word = new Text();

        @Override
        protected void map(Object key, Text value, Context context) throws IOException, InterruptedException {

            StringTokenizer tokenizer = new StringTokenizer(value.toString());
            while (tokenizer.hasMoreTokens()) {
                String token = tokenizer.nextToken();
                word.set(token);
                context.write(word, ONE);
            }
        }
    }

    public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {

        private IntWritable count = new IntWritable();

        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {

            int sum = 0;
            for (IntWritable value : values) {
                sum += value.get();
            }
            count.set(sum);
            context.write(key, count);
        }
    }

    public int run(String[] arg0) throws Exception {
        Job job = new Job(getConf());
        job.setJarByClass(WordCount.class);
        job.setJobName("wordcount");

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        job.setMapperClass(MapClass.class);
        job.setReducerClass(Reduce.class);

        FileInputFormat.setInputPaths(job, new Path("/tmp/wordcount/in"));
        FileOutputFormat.setOutputPath(job, new Path("/tmp/wordcount/out"));

        boolean success = job.waitForCompletion(true);
        return success ? 0 : 1;
    }

}