MapReduce-Reduce端join操作-Map阶段代码

p0001,小米5,1000,2000
p0002,锤子T1,1000,3000

定义 Mapper

package cn.learn.mapreduce_reduce_join;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

import java.io.IOException;

public class ReduceJoinMapper extends Mapper<LongWritable,Text,Text,Text> {
    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, 
InterruptedException {
       //首先判断数据来自哪个文件
        FileSplit fileSplit = (FileSplit) context.getInputSplit();
        String fileName = fileSplit.getPath().getName();

        if(fileName.equals("orders.txt")){
        //获取pid
            String[] split = value.toString().split(",");
            context.write(new Text(split[2]), value);
        }else{
            //获取pid
            String[] split = value.toString().split(",");
            context.write(new Text(split[0]), value);
        }
    }
}