Hadoop MapReduce实现人员二度关系运算

1、一度人脉：双方直接是好友

2、二度人脉：双方有一个以上共同的好友，这时朋友网可以计算出你们有几个共同的好友并且呈现数字给你。你们的关系是： 你->朋友->陌生人

3、三度人脉：即你朋友的朋友的朋友就是这个陌生人。你们的关系是 你->朋友->朋友->陌生人

4、四度人脉：比三度增加一度，你们的关系是，你->朋友->朋友->朋友->陌生人

5、五度人脉：你->朋友->朋友->朋友->朋友->陌生人 ，像上面这张图片表示的就是一个五度人脉关系。

6、六度人脉：你->朋友->朋友->朋友->朋友->朋友->陌生人

求下图的二度人员关系：

数据格式如下：

A,B
A,C
A,E
B,D
E,D
C,F
F,G

实现如下：

package com.gm.hadoop.mapreduce;

import java.io.IOException;
import java.util.Vector;

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 org.apache.hadoop.util.GenericOptionsParser;

public class App_2_Friend {

	// map1
	public static class Map1 extends Mapper<Object, Text, Text, Text> {
		private Text map1_key = new Text();
		private Text map1_value = new Text();

		@Override
		protected void map(Object key, Text value, Context context)
				throws IOException, InterruptedException {
			String[] eachterm = value.toString().split(",");
			if (eachterm.length != 2) {
				return;
			}

			if (eachterm[0].compareTo(eachterm[1]) < 0) {
				map1_value.set(eachterm[0] + "\t" + eachterm[1]);
			} else if (eachterm[0].compareTo(eachterm[1]) > 0) {
				map1_value.set(eachterm[1] + "\t" + eachterm[0]);
			}

			map1_key.set(eachterm[0]);
			context.write(map1_key, map1_value);

			map1_key.set(eachterm[1]);
			context.write(map1_key, map1_value);
		}
	}

	// reduce1
	public static class Reduce1 extends Reducer<Text, Text, Text, Text> {
		@Override
		protected void reduce(Text key, Iterable<Text> values, Context context)
				throws IOException, InterruptedException {
			Vector<String> hisFriends = new Vector<String>();

			for (Text val : values) {
				String[] eachterm = val.toString().split("\t");
				if (eachterm[0].equals(key.toString())) {
					hisFriends.add(eachterm[1]);
					context.write(val, new Text("deg1friend"));
				}
				if (eachterm[1].equals(key.toString())) {
					hisFriends.add(eachterm[0]);
					context.write(val, new Text("deg1friend"));
				}
			}

			for (int i = 0; i < hisFriends.size(); i++) {
				for (int j = 0; j < hisFriends.size(); j++) {
					if (hisFriends.elementAt(i).compareTo(
							hisFriends.elementAt(j)) < 0) {
						Text reduce_key = new Text(hisFriends.elementAt(i)
								+ "\t" + hisFriends.elementAt(j));
						context.write(reduce_key, new Text("deg2friend"));
					}
				}
			}
		}
	}

	// map2
	public static class Map2 extends Mapper<Object, Text, Text, Text> {
		@Override
		protected void map(Object key, Text value, Context context)
				throws IOException, InterruptedException {

			String[] line = value.toString().split("\t");
			if (line.length == 3) {
				Text map2_key = new Text(line[0] + "\t" + line[1]);
				Text map2_value = new Text(line[2]);
				context.write(map2_key, map2_value);
			}

		}
	}

	// reduce2
	public static class Reduce2 extends Reducer<Text, Text, Text, Text> {
		@Override
		protected void reduce(Text key, Iterable<Text> values, Context context)
				throws IOException, InterruptedException {
			boolean isdeg1 = false;
			boolean isdeg2 = false;
			int count = 0;

			for (Text val : values) {
				if (val.toString().compareTo("deg1friend") == 0) {
					isdeg1 = true;
				}
				if (val.toString().compareTo("deg2friend") == 0) {
					isdeg2 = true;
					count++;
				}
			}
			if ((!isdeg1) && isdeg2) {
				context.write(new Text(String.valueOf(count)), key);
			}
		}
	}

	// main
	public static void main(String[] args) throws Exception {

		System.setProperty("hadoop.home.dir", "E:/hadoop-2.8.0");
		//HADOOP_HOME and hadoop.home.dir are unset.

		Configuration conf = new Configuration();  

		/*String[] otherArgs = new GenericOptionsParser(conf, args)
				.getRemainingArgs();*/
		/*if (otherArgs.length != 3) {
			System.err.println("Usage: Deg2friend <in> <temp> <out>");
			System.exit(2);
		}*/
		String in_path = "C:/rmgx.txt";
		String temp_path = "C:/temp.txt";
		String out_path = "C:/result.txt";

	    Job job1 = Job.getInstance(conf, "Deg2friend");
		job1.setJarByClass(App_2_Friend.class);
		job1.setMapperClass(Map1.class);
		job1.setReducerClass(Reduce1.class);
		job1.setOutputKeyClass(Text.class);
		job1.setOutputValueClass(Text.class);

		/*FileInputFormat.addInputPath(job1, new Path(otherArgs[0]));
		FileOutputFormat.setOutputPath(job1, new Path(otherArgs[1]));*/

		FileInputFormat.addInputPath(job1, new Path(in_path));
		FileOutputFormat.setOutputPath(job1, new Path(temp_path));

		if (job1.waitForCompletion(true)) {
			Job job2 = Job.getInstance(conf, "Deg2friend");
			job2.setJarByClass(App_2_Friend.class);
			job2.setMapperClass(Map2.class);
			job2.setReducerClass(Reduce2.class);
			job2.setOutputKeyClass(Text.class);
			job2.setOutputValueClass(Text.class);
			/*FileInputFormat.addInputPath(job2, new Path(otherArgs[1]));
			FileOutputFormat.setOutputPath(job2, new Path(otherArgs[2]));*/

			FileInputFormat.addInputPath(job2, new Path(temp_path));
			FileOutputFormat.setOutputPath(job2, new Path(out_path));

			System.exit(job2.waitForCompletion(true) ? 0 : 1);

		}
		System.exit(job1.waitForCompletion(true) ? 0 : 1);
	}
}