MR-找朋友

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package findfriends;

import java.io.IOException;
import java.util.Set;
import java.util.TreeSet;

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;

public class FindFriends {
           public static class FindMap extends Mapper<Object,Text,Text,Text>{
        	   public void map(Object key,Text value,Context context)throws IOException , InterruptedException{
        		   Set<String> set = new TreeSet<String>();
        		   String[] str = new String[value.toString().split(" ").length];
        		   str=value.toString().split(" ");
        		   for(int i=0;i<str.length;i++){
        			   set.add(str[i]);
        		   }
        		   String[] friends = new String[set.size()];
        		   friends = set.toArray(friends);
        		   for(int i=0;i<friends.length;i++)
        			   for(int j=i+1;j<friends.length;j++){
        				   String friend = friends[i]+friends[j];
        				   context.write(new Text(friend), new Text(str[0])); 
        			   }
        	   }
           }
           public static class FindReduce extends Reducer<Text,Text,Text,Text>{
        	   public void reduce(Text key,Iterable<Text> values,Context context)throws IOException,InterruptedException{
        		   String value = "";
        		   for(Text val:values){
        			   if(value==""){
        				   value=val.toString();
        			   }
        			   else{
        				   value=value+":"+val.toString();
        			   }
        		   }
        		   context.write(key, new Text(value));
        	   }
           }
           public static void main(String[] args)throws IOException, ClassNotFoundException, InterruptedException{
        	   Configuration conf = new Configuration();
        	   Job job = new Job(conf,"findfriends");
        	   job.setJarByClass(FindFriends.class);
        	   job.setMapperClass(FindMap.class);
        	   job.setReducerClass(FindReduce.class);
        	   job.setOutputKeyClass(Text.class);
        	   job.setOutputValueClass(Text.class);
        	   job.setNumReduceTasks(1);
        	   FileInputFormat.addInputPath(job, new Path(args[0]));
        	   FileOutputFormat.setOutputPath(job, new Path(args[1]));
        	   System.exit(job.waitForCompletion(true)?0:1);
           }
}

MR-找朋友

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原文地址：http://blog.csdn.net/zhangpengfei104/article/details/48024935