使用复合键值对对key和value排序

 1 package keySort;
 2 import java.io.IOException;
 3 
 4 import org.apache.hadoop.conf.Configuration;
 5 import org.apache.hadoop.io.Text;
 6 import org.apache.hadoop.mapreduce.Job;
 7 import org.apache.hadoop.mapreduce.Mapper;
 8 import org.apache.hadoop.mapreduce.Partitioner;
 9 import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
10 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
11 import org.apache.hadoop.fs.Path;
12 public class keySort {
13     public static class MyMapper extends Mapper<Object, Text, Text, Text> {
14         private Text map_value=new Text("hello");        
15         public void map(Object key,Text value,Context context) throws IOException, InterruptedException{
16             context.write(value, map_value);
17         }
18     }
19     
20     public static class MyPartitioner extends Partitioner<Text, Text>{
21         public Text realKey=new Text();
22         @Override
23         public int getPartition(Text key, Text value, int numredtasks) {
24             // TODO 自动生成的方法存根
25             String[] kk=key.toString().split("\t");
26             realKey.set(kk[0]);
27             System.out.println("partition key is:"+realKey.toString());
28             return ((realKey.hashCode()&Integer.MAX_VALUE)%numredtasks);
29         }
30         
31     }
32 
33     public static void main(String[] args) throws Exception
34     {
35         if(args.length!=2){
36             System.err.println("Usage: MatrixMultiply <inputPathM> <inputPathN> <outputPath>");
37              System.exit(2);
38                    }
39         Configuration conf=new Configuration();
40         Job job=new Job(conf,"SeconderySort");
41         job.setNumReduceTasks(1);//设置为0的话，并不会执行分区过程，也就不能利用符合jian zhi
42         job.setJarByClass(keySort.class);
43         job.setMapperClass(MyMapper.class);
44         job.setPartitionerClass(MyPartitioner.class);
45         job.setOutputKeyClass(Text.class);
46         job.setOutputValueClass(Text.class);
47         FileInputFormat.setInputPaths(job, new Path(args[0]));
48         FileOutputFormat.setOutputPath(job, new Path(args[1]));
49         System.exit(job.waitForCompletion(true)?0:1);
50         
51     }
52         
53     }
54     
55     
56     
57     
58