Hadoop中排序

import java.io.IOException;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
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;

class Map extends Mapper<Object, Text, IntWritable, IntWritable>{
    public void map (Object key, Text value, Context context)
        throws IOException, InterruptedException{
        String line = value.toString();
        int num = Integer.parseInt(line);
        context.write(new IntWritable(num), new IntWritable(1));
    }
}

class Reduce extends Reducer<IntWritable, IntWritable,IntWritable,IntWritable>{
    private static int lineNum = 1;
    public void reduce (IntWritable key, Iterable<IntWritable> values, Context context)
        throws IOException, InterruptedException{
            for(IntWritable val:values){
                context.write(new IntWritable(lineNum),key);
                lineNum++;
            }
    }
}
public  class Sort{
    public static void main (String[] args) throws Exception{
        if (args.length != 2){
            System.err.println("can shu shao yu liang ge");
            System.exit(-1);
        }
        
        Job job = new Job();
        job.setJarByClass(Sort.class);
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
        
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        
        job.setOutputKeyClass(IntWritable.class);
        job.setOutputValueClass(IntWritable.class);
        System.exit(job.waitForCompletion(true)?0:1);
}    
}