mapreducr案例_好友关系

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.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;

class PersonMapper extends Mapper<LongWritable, Text,Text,LongWritable>{
    @Override
    protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, LongWritable>.Context context) throws IOException, InterruptedException {
        String line = value.toString();
        String[] split = line.split(" ");
//      tom hello hadoop cat
        for (int i =0;i<split.length-1;i++){
            for (int j=i+1;j<split.length;j++){
                String res = compare(split[i], split[j]);
                if (i==0){
                    context.write(new Text(res),new LongWritable(1L));
                }else {
                    context.write(new Text(res),new LongWritable(-1L));
                }

            }
        }
    }

    public static String compare(String s1,String s2){
        if (s1.compareTo(s2)<0){
            return s1+"-"+s2;
        }else {
            return s2+"-"+s1;
        }
    }
}

class PersonReducer extends Reducer<Text,LongWritable,Text,Text>{
    @Override
    protected void reduce(Text key, Iterable<LongWritable> values, Reducer<Text, LongWritable, Text, Text>.Context context) throws IOException, InterruptedException {
        boolean flag = true;
        for (LongWritable value : values) {
            long l = value.get();
            if (l==1){
                context.write(key,new Text("直接好友"));
                flag=false;
                break;
            }
        }
        if (flag){
            context.write(key,new Text("间接好友"));
        }
    }
}


public class PersonDemo {
    public static void main(String[] args) throws Exception{
        Configuration conf = new Configuration();
        conf.set("fs.defaultFS", "hdfs://master:9000");

        Job job = Job.getInstance(conf);

        job.setJarByClass(PersonDemo.class);

        job.setJobName("好友关系统计案例");

        job.setMapperClass(PersonMapper.class);

        job.setReducerClass(PersonReducer.class);

        job.setMapOutputKeyClass(Text.class);

        job.setMapOutputValueClass(LongWritable.class);

        job.setOutputKeyClass(Text.class);

        job.setOutputValueClass(Text.class);

        FileInputFormat.setInputPaths(job,new Path(args[0]));

        FileOutputFormat.setOutputPath(job,new Path(args[1]));

        boolean b = job.waitForCompletion(true);
        if (b){
            System.out.println("好友关系案例mapreduce实现执行成功！>_-");
        }else {
            System.out.println("好友关系案例mapreduce实现执行失败");
        }


    }
}