Hadoop 默认排序

Hadoop  默认排序

1       3

1       2

1       1

3       3

3       2

2       2

2       1

3       1

排序后：左右前面一列排序 后面一列不排序  要想第二列也排序  请看  Hadoop二次排序

1 3

1 2

1 1

2 2

2 1

3 3

3 2

3 1

代码为：

package com.hadoop.test.defaultsort;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.Mapper;

public class DefaultSortMapper extends Mapper<LongWritable, Text, LongWritable, LongWritable> {

@Override

protected void map(LongWritable key, Text value,

Context context)

throws IOException, InterruptedException {

String line = value.toString();

String[] arr = line.split("\t");

if(arr.length==2){

context.write(new LongWritable(Long.parseLong(arr[0])), new LongWritable(Long.parseLong(arr[1])));

}

}

}

package com.hadoop.test.defaultsort;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.mapreduce.Reducer;

public class Sortreducer extends Reducer<LongWritable, LongWritable, LongWritable, LongWritable> {

@Override

protected void reduce(LongWritable key, Iterable<LongWritable> values,Context context)

throws IOException, InterruptedException {

for (LongWritable value : values) {

context.write(key, value);

}

}

}

package com.hadoop.test.defaultsort;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.FileSystem;

import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.mapreduce.Job;

import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;

import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

/**

* 默认key排序 安装升序排序

* @author 小明

*

*/

public class JobMain {

public static void main(String[] args) throws Exception{

Configuration configuration = new Configuration();

Job job = new Job(configuration, "default-sort");

job.setJarByClass(JobMain.class);

job.setMapperClass(DefaultSortMapper.class);

job.setMapOutputKeyClass(LongWritable.class);

job.setMapOutputValueClass(LongWritable.class);

job.setReducerClass(Sortreducer.class);

job.setOutputKeyClass(LongWritable.class);

job.setOutputValueClass(LongWritable.class);

FileInputFormat.addInputPath(job, new Path(args[0]));

Path outputDir= new Path(args[1]);

FileSystem sys = FileSystem.get(configuration);

if(sys.exists(outputDir)){

sys.delete(outputDir, true);

}

FileOutputFormat.setOutputPath(job, outputDir);

job.waitForCompletion(true);

}

}