Hadoop系列修炼入门笔记14

核心内容：

多输入

MutltiInputs（多输入）;使用多个输入作为job的输入来源。

也就是在InputFormat 前把添加各种不同的序列源
里面的方法也就是 addInputPath等等。。。。
map也可以在这个流程中套进来。

1.文本件TextFile的Map函数：

package com.shujuelin.hdfs.mr.shujuelin.hdfs.mr.multiinput;

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;

/**
 * 文本文件Text的Map
 */
public class WCTextMapper extends Mapper {

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        Text keyOut = new Text();
        IntWritable valueOut = new IntWritable();
        String[] arr = value.toString().split(" ");
        for(String s : arr){
            keyOut.set(s);
            valueOut.set(1);
            context.write(keyOut,valueOut);
        }
    }
}

2.序列文件SequenceFile的map函数：

package com.shujuelin.hdfs.mr.shujuelin.hdfs.mr.multiinput;


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

import java.io.IOException;

/**
 *Seqt 序列文件的 Map
 */
public class WCSeqtMapper extends Mapper {

    protected void map(IntWritable key, Text value, Context context) throws IOException, InterruptedException {
        Text keyOut = new Text();
        IntWritable valueOut = new IntWritable();
        String[] arr = value.toString().split(" ");
        for(String s : arr){
            keyOut.set(s);
            valueOut.set(1);
            context.write(keyOut,valueOut);
        }
    }
}

3、Reduce函数：

package com.shujuelin.hdfs.mr.shujuelin.hdfs.mr.multiinput;

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

import javax.xml.soap.Text;
import java.io.IOException;

public class WCReducer extends Reducer {

    @Override
    protected void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException {
        int count = 0 ;
        for(IntWritable iw : values){
            count = count + iw.get() ;
        }
        String tno = Thread.currentThread().getName();
        System.out.println(tno + " : WCReducer :" + key.toString() + "=" + count);
        context.write(key,new IntWritable(count));
    }
}

4、主函数

package com.shujuelin.hdfs.mr.shujuelin.hdfs.mr.multiinput;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.MultipleInputs;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import javax.xml.soap.Text;
import java.io.IOException;

/**
 * 多个输出
 */
public class WCApp {

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {

        Configuration conf = new Configuration();

        conf.set("fs.defaultFS", "file:///");

        Job job = Job.getInstance(conf);

        //设置job的各种属性
        job.setJobName("WCAppMulti");                        //作业名称
        job.setJarByClass(WCApp.class);                 //搜索类

        //多个输入
        MultipleInputs.addInputPath(job,new Path("file///e:/compress/hadoop01"),TextInputFormat.class,WCTextMapper.class);
        MultipleInputs.addInputPath(job,new Path("file///e:/compress/hadoop01"),SequenceFileInputFormat.class,WCSeqtMapper.class);

        //设置输出
        FileOutputFormat.setOutputPath(job,new Path(args[0]));

        job.setReducerClass(WCReducer.class);           //reducer类

        job.setNumReduceTasks(3);                       //reduce个数


        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);     //

        job.waitForCompletion(true);
    }

}

end:坚持