wordcount_localIMC.java

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.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class wordcount_localIMC {
	public static class TokenizerMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

	    @Override
	    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
	        IntWritable writableCount = new IntWritable();
	        Text text = new Text();
	        Map<String,Integer> tokenMap = new HashMap<String, Integer>();
	        StringTokenizer tokenizer = new StringTokenizer(value.toString());

	        while(tokenizer.hasMoreElements()){
	            String token = tokenizer.nextToken();
	            Integer count = tokenMap.get(token);
	            if(count == null) count = new Integer(0);
	            count+=1;
	            tokenMap.put(token,count);
	        }

	        Set<String> keys = tokenMap.keySet();
	        for (String s : keys) {
	             text.set(s);
	             writableCount.set(tokenMap.get(s));
	             context.write(text,writableCount);
	        }
	    }
	}
  public static class IntSumReducer 
       extends Reducer<Text,IntWritable,Text,IntWritable> {
    private IntWritable result = new IntWritable();
    public void reduce(Text key, Iterable<IntWritable> values, 
                       Context context
                       ) throws IOException, InterruptedException {
      int sum = 0;
      for (IntWritable val : values) {
        sum += val.get();
      }
      result.set(sum);
      context.write(key, result);
    }
  }
  public static void main(String[] args) throws Exception {
    Configuration conf = new Configuration();
    String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
    if (otherArgs.length != 2) {
      System.err.println("Usage: wordcount <in> <out>");
      System.exit(2);
    }
    Job job = new Job(conf, "word count");
    job.setJarByClass(wordcount_localIMC.class);
    job.setMapperClass(TokenizerMapper.class);
    job.setCombinerClass(IntSumReducer.class);
    job.setReducerClass(IntSumReducer.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
    FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);
  }
}