hadoop-2.6.1 winutil处理

HDFS

words

hello	tom
hello	jerry
hello	kitty
hello	world
hello	tom

Map阶段

1.每次读一行数据,

2.拆分每行数据,

3.每个单词碰到一次写个1

<0, "hello tom">

<10, "hello jerry">

<22, "hello kitty">

<34, "hello world">

<46, "hello tom">

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;

public class WordCountMap extends Mapper{
    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        //读取每行文本
        String line = value.toString();
        //splite拆分每行
        String[] words = line.split(" ");//分词
        //取出每个单词
        for(String word : words) {
            //将单词转为Text类型
            Text wordText = new Text(word);
            //将1转变为IntWritable
            IntWritable outValue = new IntWritable(1);
            //写出单词,跟对应1
            context.write(wordText, outValue);
        }
    }
}

reduce阶段

1.把单词对应的那些1

2遍历,

3求和

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;


public class WordCountReduce extends Reducer{
    
    @Override
    protected void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException {
        int sum=0;
        //遍历一群1
        for(IntWritable i:values){
            sum+=i.get();
        }
        context.write(key,new IntWritable(sum));
    }
}

 使用对象

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;;
import org.apache.hadoop.mapreduce.Job;

public class WordCount {
    public static void main(String[] args) throws Exception {
        //定义配置对象
        Configuration conf=new Configuration();
        //定义一个工作任务对象
        Job job=Job.getInstance(conf);

        //获取map阶段的一个对象
        job.setMapperClass(WordCountMap.class);
        //指定map阶段的一个输出key
        job.setMapOutputKeyClass(Text.class);
        //指定map阶段输出的values类型
        job.setMapOutputValueClass(IntWritable.class);
        //map阶段的输入文件
        FileInputFormat.setInputPaths(job,new Path("C:\Users\1234\Desktop\123.txt"));

        //指定Reduce的类
        job.setReducerClass(WordCountReduce.class);
        //指定reduce阶段的一个输出key
        job.setOutputKeyClass(Text.class);
        //指定reduce阶段输出的values类型
        job.setOutputValueClass(IntWritable.class);
        //指定reduce阶段的输出文件
        FileOutputFormat.setOutputPath(job,new Path("C:\Users\1234\Desktop\456"));

        //submit
        job.waitForCompletion(true);
    }
}

处理后数据

hello        5 

jerry         1

kitty         1

tom          2

world       1