com.example.Driver.java Source code

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Here is the source code for com.example.Driver.java

Source

/*
 * Driver.java
 * 
 * Copyright 2014 Luca Menichetti <meniluca@gmail.com>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 * 
 */

package com.example;

import java.util.Arrays;

import org.apache.hadoop.conf.Configuration;
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.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;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.log4j.Logger;

public class Driver extends Configured implements Tool {

    private static Logger logger = Logger.getLogger(Driver.class);

    public static void main(String[] args) throws Exception {
        try {
            int res = ToolRunner.run(new Configuration(), (Tool) new Driver(), args);
            System.exit(res);
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(255);
        }
    }

    public int run(String[] args) throws Exception {

        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "Your job name");

        job.setJarByClass(Driver.class);

        logger.info("job " + job.getJobName() + " [" + job.getJar() + "] started with the following arguments: "
                + Arrays.toString(args));

        if (args.length < 2) {
            logger.warn("to run this jar are necessary at 2 parameters \"" + job.getJar()
                    + " input_files output_directory");
            return 1;
        }

        job.setMapperClass(WordcountMapper.class);
        logger.info("mapper class is " + job.getMapperClass());

        //job.setMapOutputKeyClass(Text.class);
        //job.setMapOutputValueClass(IntWritable.class);
        logger.info("mapper output key class is " + job.getMapOutputKeyClass());
        logger.info("mapper output value class is " + job.getMapOutputValueClass());

        job.setReducerClass(WordcountReducer.class);
        logger.info("reducer class is " + job.getReducerClass());
        job.setCombinerClass(WordcountReducer.class);
        logger.info("combiner class is " + job.getCombinerClass());
        //When you are not runnign any Reducer
        //OR    job.setNumReduceTasks(0);
        //      logger.info("number of reduce task is " + job.getNumReduceTasks());

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        logger.info("output key class is " + job.getOutputKeyClass());
        logger.info("output value class is " + job.getOutputValueClass());

        job.setInputFormatClass(TextInputFormat.class);
        logger.info("input format class is " + job.getInputFormatClass());

        job.setOutputFormatClass(TextOutputFormat.class);
        logger.info("output format class is " + job.getOutputFormatClass());

        Path filePath = new Path(args[0]);
        logger.info("input path " + filePath);
        FileInputFormat.setInputPaths(job, filePath);

        Path outputPath = new Path(args[1]);
        logger.info("output path " + outputPath);
        FileOutputFormat.setOutputPath(job, outputPath);

        job.waitForCompletion(true);
        return 0;
    }
}