WordCount.java

/**
 * Copyright (c) 2009-2011 VMware, Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.springsource.insight.plugin.hadoop;

import java.io.File;
import java.io.IOException;

import org.apache.commons.io.FileUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
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;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import com.springsource.insight.util.FileUtil;

public class WordCount extends Configured implements Tool {
    public WordCount() {
        super();
    }

    static public class WordCountMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
        final private static LongWritable ONE = new LongWritable(1);
        private Text tokenValue = new Text();

        @Override
        protected void map(LongWritable offset, Text text, Context context) throws IOException, InterruptedException {
            for (String token : text.toString().split("\\s+")) {
                tokenValue.set(token);
                context.write(tokenValue, ONE);
            }
        }
    }

    static public class WordCountReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
        private LongWritable total = new LongWritable();

        @Override
        protected void reduce(Text token, Iterable<LongWritable> counts, Context context)
                throws IOException, InterruptedException {
            long n = 0;
            for (LongWritable count : counts)
                n += count.get();
            total.set(n);
            context.write(token, total);
            System.out.println(token + "," + total);
        }
    }

    public int run(String[] args) throws Exception {
        String INPUT = "src/test/resources";
        String OUTPUT = "target/out";

        Configuration conf = new Configuration();
        File targetFolder = FileUtil.detectTargetFolder(getClass());
        if (targetFolder == null) {
            throw new IllegalStateException("Cannot detect target folder");
        }
        File tempFolder = new File(targetFolder, "temp");
        conf.set("hadoop.tmp.dir", tempFolder.getAbsolutePath());

        Job job = new Job(conf, "wordcount");
        job.setJarByClass(WordCount.class);

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

        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(LongWritable.class);

        FileUtils.deleteDirectory(new File(OUTPUT)); // delete old output data
        FileInputFormat.addInputPath(job, new Path(INPUT));
        FileOutputFormat.setOutputPath(job, new Path(OUTPUT));

        return job.waitForCompletion(true) ? 0 : -1;
    }

    public static void main(String[] args) throws Exception {
        System.exit(ToolRunner.run(new WordCount(), args));
    }
}