Count occurrences of words mapreduce

1, the new Java project

2, guide package
E: \ tools \ big data \ big data to enhance data \ 01- software data \ 06-Hadoop \ installer \ Java1.8
compiler environment \ hadoop-2.7.3 \ hadoop-2.7.3 \ share \ hadoop \ MapReduce
+ HSFS of those packages + common

3, write project

3.1 WCMapper

package com.zy.wc;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class WCMapper extends Mapper<LongWritable, Text, Text, LongWritable>{
//map
    /*
     * 输入<0,"tom lili tom"> 输出<"tom",1>
     * */

//public class WCMapper extends Mapper<KEYIN, VALUEIN, KEYOUT,VALUEOUT>
// 输入的key  long  value  String    输出的  key String  value long类型

@Override            //数字              // String 
protected  void Map (LongWritable Key, the Text value, Mapper <LongWritable, the Text, the Text, LongWritable> .context context)
         throws IOException, InterruptedException {
     // value of the input character string is a line of "Tom Lili Tom"
     // segmentation 
    . String [] = value.toString Split () Split ( "\ T" ); // Tab keys spaced tabs
     for (String name: Split) {
         // Mapper outputting content 
        context.write ( new new the Text (name) , new new LongWritable (. 1 )); 
        
    } 
} 
}

3.2 WCReduce

package com.zy.wc;

import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.WordCount.Reduce;
import org.apache.hadoop.mapreduce.Reducer;

public class WCReduce extends  Reducer<Text,LongWritable,Text,LongWritable>{
    //输入<"tom",{1,1,1,1,1,1,1}>   输出<"tom",7>
           
@Override                 // input key         // input values 
protected  void the reduce (the Text Key, the Iterable <LongWritable> value, 
        the Reducer <the Text, LongWritable, the Text, LongWritable> .context context) throws IOException, InterruptedException {
     // iterative calculation in which the accumulation of 1 value 
    Long SUM = 0 ;
     for (LongWritable LongWritable: value) { 
        SUM + =. 1 ; 
        
    } 
    // key output 
    context.write (Key, new new LongWritable (SUM)); 
} 


}

3.3 WCApp

package com.zy.wc;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
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;

public class WCApp {

    public static void main(String[] args) throws Exception {
        //创建配置对象
        Configuration = the Configuration new new the Configuration ();
         // get job instance 
        the Job job = Job.getInstance (Configuration);
         // specified to run job class 
        job.setJarByClass (WCApp. Class ); 
        
        // specified in the job Mapper 
        job.setMapperClass (WCMapper . class );
         // specified mapper keys and values of the output type 
        job.setMapOutputKeyClass (the Text. class ); 
        job.setMapOutputValueClass (LongWritable. class ); 
        
        // specified in the reducer job 
        . job.setReducerClass (WCReduce class );
        job.setMapOutputKeyClass (the Text. class ); 
        job.setMapOutputValueClass (LongWritable. class ); 
        
        // specified input file 
        FileInputFormat.setInputPaths (Job, new new the Path ( "/ wc.txt" ));
         // the specified output file 
        FileOutputFormat.setOutputPath ( job, new new the Path ( "/ myWCResult" ));
         // submit jobs 
        job.waitForCompletion ( to true ); 
        
    } 

}

4, package upload

The project package (java labeled jar package, web projects labeled as war package), upload it to linux, and then run the jar package hadoop jar WCAPP.jar