io.aos.t4f.hadoop.mapred.WordCountMapReduceTest.java Source code

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package io.aos.t4f.hadoop.mapred;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

/**
 * This is an example Hadoop Map/Reduce application.
 * It reads the text input files, breaks each line into words
 * and counts them. The output is a locally sorted list of words and the 
 * count of how often they occurred.
 *
 * To run: bin/hadoop jar build/hadoop-examples.jar wordcount
 *            [-m <i>maps</i>] [-r <i>reduces</i>] <i>in-dir</i> <i>out-dir</i> 
 */
public class WordCountMapReduceTest extends Configured implements Tool {

    static int printUsage() {
        System.out.println("wordcount [-m <maps>] [-r <reduces>] <input> <output>");
        ToolRunner.printGenericCommandUsage(System.out);
        return -1;
    }

    /**
     * The main driver for word count map/reduce program.
     * Invoke this method to submit the map/reduce job.
     * @throws IOException When there is communication problems with the 
     *                     job tracker.
     */
    public int run(String[] args) throws Exception {
        JobConf conf = new JobConf(getConf(), WordCountMapReduceTest.class);
        conf.setJobName("wordcount");

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

        conf.setMapperClass(WordCountMapper.class);
        conf.setCombinerClass(WordCountReducer.class);
        conf.setReducerClass(WordCountReducer.class);

        List<String> other_args = new ArrayList<String>();
        for (int i = 0; i < args.length; ++i) {
            try {
                if ("-m".equals(args[i])) {
                    conf.setNumMapTasks(Integer.parseInt(args[++i]));
                } else if ("-r".equals(args[i])) {
                    conf.setNumReduceTasks(Integer.parseInt(args[++i]));
                } else {
                    other_args.add(args[i]);
                }
            } catch (NumberFormatException except) {
                System.out.println("ERROR: Integer expected instead of " + args[i]);
                return printUsage();
            } catch (ArrayIndexOutOfBoundsException except) {
                System.out.println("ERROR: Required parameter missing from " + args[i - 1]);
                return printUsage();
            }
        }
        // Make sure there are exactly 2 parameters left.
        if (other_args.size() != 2) {
            System.out.println("ERROR: Wrong number of parameters: " + other_args.size() + " instead of 2.");
            return printUsage();
        }
        FileInputFormat.setInputPaths(conf, other_args.get(0));
        FileOutputFormat.setOutputPath(conf, new Path(other_args.get(1)));

        JobClient.runJob(conf);
        return 0;
    }

    public static void main(String... args) throws Exception {
        int res = ToolRunner.run(new Configuration(), new WordCountMapReduceTest(), args);
        System.exit(res);
    }

}