MyGroup.java

package com.libin.api.mapreduce;

import java.io.IOException;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
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.GenericOptionsParser;

/**
 * Copyright (c) 2016/04/01. xixi Inc. All Rights Reserved.
 * Authors: libin <2578858653@qq.com>
 * <p>
 * Purpose : Hadoop自定义分组Group
 */
public class MyGroup {
    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Configuration conf = new Configuration();
        String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
        if (otherArgs.length != 2) {
            System.err.println("Usage databaseV1 <inputpath> <outputpath>");
        }

        Job job = Job.getInstance(conf, MyGroup.class.getSimpleName() + "1");
        job.setJarByClass(MyGroup.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(Text.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
        job.setMapperClass(MyMapper1.class);
        job.setGroupingComparatorClass(MyGroupComparator.class);
        job.setReducerClass(MyReducer1.class);
        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
        job.waitForCompletion(true);
    }

    public static class MyMapper1 extends Mapper<LongWritable, Text, Text, Text> {
        @Override
        protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, Text>.Context context)
                throws IOException, InterruptedException {
            String[] spl = value.toString().split("\t");
            context.write(new Text(spl[0].trim()), new Text(spl[1].trim()));
        }
    }

    public static class MyReducer1 extends Reducer<Text, Text, Text, Text> {
        @Override
        protected void reduce(Text k2, Iterable<Text> v2s, Reducer<Text, Text, Text, Text>.Context context)
                throws IOException, InterruptedException {
            Long count = 0L;
            for (@SuppressWarnings("unused") Text v2 : v2s) {
                count++;
                context.write(new Text("in--" + k2), new Text(count.toString()));
            }
            context.write(new Text("out--" + k2), new Text(count.toString()));
        }
    }

    public static class MyGroupComparator extends WritableComparator {
        public MyGroupComparator() {
            super(Text.class, true);
        }

        @SuppressWarnings("rawtypes")
        public int compare(WritableComparable a, WritableComparable b) {
            Text p1 = (Text) a;
            Text p2 = (Text) b;
            p1.compareTo(p2);
            return 0;
        }
    }
}