IDEA上找博客共同好友案例

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FFMapper1类：

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package com.atguigu.friend;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class FFMapper1 extends Mapper<LongWritable,Text,Text,Text> {
    private Text k = new Text();
    private Text v = new Text();

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String[] split = value.toString().split(":");
        //关注者作为value
        v.set(split[0]);

        //被关注者作为key
        for (String man : split[1].split(",")) {
            k.set(man);
            context.write(k,v);
        }
    }
}

FFReducer1类：

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package com.atguigu.friend;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class FFReducer1 extends Reducer<Text,Text, Text,Text> {
    private Text v = new Text();
    private StringBuilder sb = new StringBuilder();

    @Override
    protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
        //被关注的人为key，关注他的人为values
        sb.delete(0,sb.length());
        for (Text value : values) {
            sb.append(value.toString()).append(",");
        }
        v.set(sb.toString());

        context.write(key,v);
    }
}

FFMapper2类:

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package com.atguigu.friend;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class FFMapper2 extends Mapper<LongWritable, Text,Text,Text> {
    private Text k = new Text();
    private Text v = new Text();

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String[] split = value.toString().split("\t");
        v.set(split[0]);

        String[] men = split[1].split(",");
        for (int i = 0; i < men.length; i++) {
            for (int i1 = i+1; i1 < men.length; i1++) {
                if(men[i].compareTo(men[i1]) > 0)
                    k.set(men[i1] + "-" + men[i]);
                else
                    k.set(men[i] + "-" + men[i1]);

                context.write(k,v);
            }

        }
    }
}

FFReducer2类：

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package com.atguigu.friend;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class FFReducer2 extends Reducer<Text,Text,Text,Text> {
    private Text v = new Text();
    private StringBuilder sb = new StringBuilder();


    @Override
    protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
        sb.delete(0,sb.length());
        for (Text value : values) {
            sb.append(value.toString()).append(",");
        }
        v.set(sb.toString());

        context.write(key,v);
    }
}

FFDriver类：

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package com.atguigu.friend;

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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class FFDriver {
    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Job job1 = Job.getInstance(new Configuration());
        job1.setJarByClass(FFDriver.class);
        job1.setMapperClass(FFMapper1.class);
        job1.setReducerClass(FFReducer1.class);

        job1.setMapOutputKeyClass(Text.class);
        job1.setMapOutputValueClass(Text.class);
        job1.setOutputKeyClass(Text.class);
        job1.setOutputValueClass(Text.class);

        FileInputFormat.setInputPaths(job1,new Path("F:/input"));
        FileOutputFormat.setOutputPath(job1,new Path("F:/output"));
        boolean b = job1.waitForCompletion(true);
        if (b) {
            Job job2 = Job.getInstance(new Configuration());
            job2.setJarByClass(FFDriver.class);
            job2.setMapperClass(FFMapper2.class);
            job2.setReducerClass(FFReducer2.class);

            job2.setMapOutputKeyClass(Text.class);
            job2.setMapOutputValueClass(Text.class);
            job2.setOutputKeyClass(Text.class);
            job2.setOutputValueClass(Text.class);

            FileInputFormat.setInputPaths(job2, new Path("F:/output"));
            FileOutputFormat.setOutputPath(job2, new Path("F:/output1"));
            boolean b2 = job2.waitForCompletion(true);
            System.exit(b2 ? 0 : 1);
        }
    }
}

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