去重

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package com.qr.mr.removeduplicate;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 java.io.IOException;

/**
 * http://www.aboutyun.com/thread-7041-1-1.html
 */
public class RemoveDuplicate {

    public static class Map extends Mapper<Object,Text, Text,Text>{
        private static Text line = new Text();
        public void map(Object key,Text value,Context context)
                throws IOException, InterruptedException {//todo
            line = value;
            context.write(line,new Text(""));
        }
    }

    public static class Reduce extends Reducer<Text,Text,Text,Text>{
        public void reduce(Text key,Iterable<Text> values,Context context)
                throws IOException, InterruptedException {//todo
            context.write(key,new Text(""));
        }
    }

    public static void main(String[] args)
            throws IOException, ClassNotFoundException, InterruptedException {//todo
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf,"RemoveDuplicate");//todo
        job.setJarByClass(RemoveDuplicate.class);

        job.setMapperClass(Map.class);
        job.setCombinerClass(Reduce.class);//todo
        job.setReducerClass(Reduce.class);

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

        FileInputFormat.addInputPath(job,new Path("/Users/lifei/qrproject/hiveudf/src/main/java/com/qr/mr/removeduplicate/in"));
        FileOutputFormat.setOutputPath(job,new Path("/Users/lifei/qrproject/hiveudf/src/main/java/com/qr/mr/removeduplicate/out"));

        System.exit(job.waitForCompletion(true) ? 0: 1);
    }
}