WordCount

Count word using Hadoop

package com.ciocomit.count;

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

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
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.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

public class WordCount {
    public static class Map extends Mapper {

        public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            String line = value.toString();
            StringTokenizer tokenizer = new StringTokenizer(line);

            while (tokenizer.hasMoreTokens()) {
                value.set(tokenizer.nextToken());
                context.write(value, new IntWritable(1));
            }
        }

    }// class

    public static class Reduce extends Reducer {

        public void reduce(Text key, Iterable values, Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable x : values) {
                sum += x.get();
            }
            context.write(key, new IntWritable(sum));
        }
    }// class

    public static void main(String[] args) throws Exception {

        Configuration conf = new Configuration();
        Job job = new Job(conf, "mywc");
       
        job.setJarByClass(WordCount.class);
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
       
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
       
        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);
       
        Path outputPath = new Path(args[1]);

        // Configuration the input/output path from the filesystem into the job
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
       
        // deleting the output path automatically from hdfs so that we don't have delete it explicity
        outputPath.getFileSystem(conf).delete(outputPath);
    }
}// class