标签：9.png set idt cte ble 框架 values key wordcount
1. Combiner概述
2. 自定义Combiner实现步骤
1). 定义一个Combiner继承Reducer,重写reduce方法
public class WordcountCombiner extends Reducer<Text, IntWritable, Text,IntWritable>{ @Override protected void reduce(Text key, Iterable<IntWritable> values,Context context) throws IOException, InterruptedException { // 1 汇总操作 int count = 0; for(IntWritable v :values){ count += v.get(); } // 2 写出 context.write(key, new IntWritable(count)); } }
2). 在Driver类中添加设置
job.setCombinerClass(WordcountCombiner.class);
效果
大数据-Hadoop生态(19)-MapReduce框架原理-Combiner合并
标签：9.png set idt cte ble 框架 values key wordcount
原文地址：https://www.cnblogs.com/duoduotouhenying/p/10110510.html
