Distinct.java Source code

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Here is the source code for Distinct.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

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.NullWritable;
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;

public class Distinct {

    private static final String tempDir = "/tmp";

    public static class TokenizerMapper1 extends Mapper<Object, Text, Text, IntWritable> {

        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            word.set(value.toString());
            context.write(word, one);
        }
    }

    public static class Reducer1 extends Reducer<Text, IntWritable, Text, NullWritable> {

        public void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {

            context.write(key, NullWritable.get());
        }
    }

    public static class TokenizerMapper2 extends Mapper<Object, Text, Text, IntWritable> {

        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text("1");

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            context.write(word, one);
        }
    }

    public static class Reducer2 extends Reducer<Text, IntWritable, IntWritable, NullWritable> {

        public void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable val : values) {
                sum += 1;
            }
            context.write(new IntWritable(sum), NullWritable.get());
        }
    }

    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: Distinct <in> <out>");
            System.exit(2);
        }
        Job job = Job.getInstance(conf, "distinct1");
        job.setJarByClass(Distinct.class);
        job.setMapperClass(TokenizerMapper1.class);
        job.setReducerClass(Reducer1.class);
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
        FileOutputFormat.setOutputPath(job, new Path(tempDir));
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        job.waitForCompletion(true);

        Configuration conf2 = new Configuration();
        Job job2 = Job.getInstance(conf2, "distinct2");
        job2.setJarByClass(Distinct.class);
        job2.setMapperClass(TokenizerMapper2.class);
        job2.setReducerClass(Reducer2.class);
        FileInputFormat.addInputPath(job2, new Path(tempDir));
        FileOutputFormat.setOutputPath(job2, new Path(otherArgs[1]));
        job2.setOutputKeyClass(Text.class);
        job2.setOutputValueClass(IntWritable.class);
        System.exit(job2.waitForCompletion(true) ? 0 : 1);
    }
}