CustomBinaryMapReduce.java

package com.manning.hip.ch3.binary;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BytesWritable;
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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public final class CustomBinaryMapReduce {
  public static class Map extends Mapper<LongWritable, BytesWritable,
      LongWritable, LongWritable> {

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

      int len = value.getLength();
      context.write(
          key,
          new LongWritable(len));
    }
  }

  public static void main(String... args) throws Exception {
    runJob(args[0], args[1]);
  }

  public static void runJob(String input,
                            String output)
      throws Exception {
    Configuration conf = new Configuration();

    Job job = new Job(conf);
    job.setJarByClass(CustomBinaryMapReduce.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(Text.class);
    job.setMapperClass(Map.class);
    job.setInputFormatClass(CustomBinaryInputFormat.class);
    job.setNumReduceTasks(0);
    job.setMapOutputValueClass(LongWritable.class);

    FileInputFormat.setInputPaths(job, new Path(input));
    Path outPath = new Path(output);
    FileOutputFormat.setOutputPath(job, outPath);

    outPath.getFileSystem(conf).delete(outPath, true);

    job.waitForCompletion(true);
  }
}