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

定義 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> {@Overrideprotected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {//首先判斷數據來自哪個文件FileSplit fileSplit = (FileSplit) context.getInputSplit();String fileName = fileSplit.getPath().getName();if(fileName.equals("orders.txt")){//獲取pidString[] split = value.toString().split(",");context.write(new Text(split[2]), value);}else{//獲取pidString[] split = value.toString().split(",");context.write(new Text(split[0]), value);}} }

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總結

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