import java.io.IOException;

 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.Mapper;

import org.apache.hadoop.mapreduce.Reducer;

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

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

import org.apache.hadoop.util.GenericOptionsParser;

 public class Sort {

     //map将输入中的value化成IntWritable类型，作为输出的key

    public static class Map extends

　　　　　　Mapper<Object,Text,IntWritable,IntWritable>{

        private static IntWritable data=new IntWritable();

        //实现map函数

        public void map(Object key,Text value,Context context)

                throws IOException,InterruptedException{

            String line=value.toString();

            data.set(Integer.parseInt(line));

            context.write(data, new IntWritable(1));

        }

    }

    //reduce将输入中的key复制到输出数据的key上，

    //然后根据输入的value-list中元素的个数决定key的输出次数

    //用全局linenum来代表key的位次

    public static class Reduce extends

            Reducer<IntWritable,IntWritable,IntWritable,IntWritable>{

        private static IntWritable linenum = new IntWritable(1);

        //实现reduce函数

        public void reduce(IntWritable key,Iterable<IntWritable> values,Context context)

                throws IOException,InterruptedException{

            for(IntWritable val:values){

                context.write(linenum, key);

                linenum = new IntWritable(linenum.get()+1);

            }

        }

    }

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

        Configuration conf = new Configuration();

        conf.set("mapred.job.tracker", "192.168.1.2:9001");

        String[] ioArgs=new String[]{"sort_in","sort_out"};

     String[] otherArgs = new GenericOptionsParser(conf, ioArgs).getRemainingArgs();

     if (otherArgs.length != 2) {

     System.err.println("Usage: Data Sort <in> <out>");

         System.exit(2);

     }

     Job job = new Job(conf, "Data Sort");

     job.setJarByClass(Sort.class);

     //设置Map和Reduce处理类

     job.setMapperClass(Map.class);

     job.setReducerClass(Reduce.class);

     //设置输出类型

     job.setOutputKeyClass(IntWritable.class);

     job.setOutputValueClass(IntWritable.class);

     //设置输入和输出目录

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

     FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));

     System.exit(job.waitForCompletion(true) ? 0 : 1);

     }

}