周总结四

周总结四

核心代码

package com.mapr;

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.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import java.io.IOException;

public class WordCountDriver {
    public static void main(String[]args)throws IOException, ClassNotFoundException, InterruptedException{
        // 1 获取配置信息以及封装任务
        Configuration configuration = new Configuration();
        Job job = Job.getInstance(configuration);
        // 2 设置jar加载路径
        job.setJarByClass(WordCountDriver.class);
        // 3 设置map和reduce类
        job.setMapperClass(WordCountMapper.class);
        job.setReducerClass(WordCountReducer.class);
        // 4 设置map输出
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);
        // 5 设置Reduce输出
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        // 6 设置输入和输出路径
        FileInputFormat.setInputPaths(job, new Path("hdfs://192.168.132.128:9000/mymapreduce1/in/MapReduceTry.txt"));
        FileOutputFormat.setOutputPath(job, new Path("hdfs://192.168.132.128:9000/mymapreduce1/out"));
        // 7 提交
        job.waitForCompletion(true);
    }
}

package com.mapr;

import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;

public class WordCountMapper extends Mapper<LongWritable,Text,Text,IntWritable>{
    Text k=new Text();
    IntWritable v=new IntWritable(1);
    protected void map(LongWritable key,Text value,Context context)throws IOException,InterruptedException{
        String line=value.toString();
        String[] words=line.split(" ");
        for(String word:words){
            k.set(word);
            context.write(k,v);
        }
    }
}
package com.mapr;

import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;

public class WordCountReducer extends Reducer<Text,IntWritable,Text,IntWritable>{
    int sum;
    IntWritable v=new IntWritable();
    protected void reduce(Text key, Iterable<IntWritable> values,Context context)throws IOException,InterruptedException{
        sum=0;
        for(IntWritable count:values){
            sum+=count.get();
        }
        v.set(sum);
        context.write(key,v);
    }
}

MapReduce实现字符统计，wordcount实现，
平均每天学习时间：2小时
代码 700行