ReduceJoin 案例 Reduce| 学习笔记

package com.liun.mr.reducejoin;

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;

import java.util.ArrayList;

import org.apache.commons.beanutils.BeanUtils;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.Reducer;

public class TableReducer<E> extends Reducer<Text, TableBean, TableBean, NullWritable> {

@Override

protected void reduce(Text key, Iterable<TableBean> values, Context context)

throws IOException, InterruptedException {

// 存储所有订单集合

ArrayList<TableBean> orderBeans = new ArrayList<>();

// 存储产品信息

TableBean pdBean = new TableBean();

for (TableBean tableBean : values) {

if ("order".equals(tableBean.getFlag())) {// 订单表

TableBean tmpBean = new TableBean();

try {

// 拷贝传递过来的每条订单数据到集合中

BeanUtils.copyProperties(tmpBean, tableBean);

orderBeans.add(tmpBean);

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

} else {// 产品表

try {

// 拷贝传递过来的产品表到内存中

BeanUtils.copyProperties(pdBean, tableBean);

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

}

}

for (TableBean tableBean : orderBeans) {

tableBean.setPname(pdBean.getPname());

// 写出

context.write(tableBean, NullWritable.get());

}

}

}