MapReduce输入文件排序_运用mapreduce的思想,实现对输入文件的排序用伪代码

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;
 
 
 
public class Sort {
 
 
 
    //map
 
    public static class SortMapper extends Mapper<Object,Text,IntWritable,IntWritable>{
 
        public void map(Object key,Text value,Context context)throws IOException,InterruptedException{
 
            String text = value.toString();
 
            int t = Integer.parseInt(text);
 
            context.write(new IntWritable(t),new IntWritable(1));
 
        }
    }
 
 
    //reduce
 
    public static class SortReducer extends Reducer<IntWritable,IntWritable,IntWritable,IntWritable>{
 
        int row=1;
 
        public void reduce(IntWritable key,Iterable<IntWritable> values,Context context)throws IOException,InterruptedException{
 
            for(IntWritable value:values) {
 
                context.write(new IntWritable(row),key);
 
                row=row+1;
 
            }
        }
    }
 
    //main
 
    public static void main(String[] args)throws Exception{
 
        Configuration conf=new Configuration();
 
        Job job=Job.getInstance(conf,"sort");
 
        job.setJarByClass(Sort.class);
 
        job.setMapperClass(SortMapper.class);
 
        job.setReducerClass(SortReducer.class);
 
        job.setOutputKeyClass(IntWritable.class);
 
        job.setOutputValueClass(IntWritable.class);
 
        FileInputFormat.addInputPath(job,new Path("input"));
 
        FileOutputFormat.setOutputPath(job,new Path("output"));
 
        System.exit(job.waitForCompletion(true)?0:1);
 
    }
 
}
 

 代码部分完成后对文件进行打包，打包步骤详细内容在上一篇文章MapReduce文件合并与去重中。

按照要求在usr/local/hadoop目录下创建两个文本文件A.txt  B.txt ，之后进行如下操作：