hadoop二次排序<转>

数据
[@zw-hadoop-master hadoop]$ hadoop fs -cat /tmp/text.txt
1    9
2    8
3    7
4    6
5    5
6    4
7    3
8    2
9    1
0    0
9    9
8    8
7    7
6    6
5    5
4    4
3    3
2    2
1    1


结果输出 （按照第二列值  分区，分组  。以及按照 第二列，第一列 依次 排序 ）：

file_0 output
>-------0
0    0

>-------2
2    2
8    2

>-------4
4    4
6    4

>-------6
4    6
6    6

>-------8
2    8
8    8


file_1 output
>-------1
1    1
9    1

>-------3
3    3
7    3

>-------5
5    5
5    5

>-------7
3    7
7    7

>-------9
1    9
9    9

class MyMap extends Mapper<LongWritable, Text,                                 Text, NullWritable> {             @Override             public void map(LongWritable ll, Text row, Context context)                     throws IOException, InterruptedException {                 context.write( new Text(row.toString()), NullWritable.get());             }         }                  class MyReducer extends Reducer<Text, NullWritable,                                    Text, NullWritable> {             Text t = new Text();             public void reduce(Text key,                      Iterable<NullWritable> values, Context context)                     throws IOException, InterruptedException {                 t.set(">-------" + key.toString().split("\t")[1]);                 context.write(t, NullWritable.get());                 for (NullWritable value : values) {                     context.write(key, NullWritable.get());                 }             }         }         // 根据第二列 %2 分区         class MyPartitioner extends Partitioner<Text, NullWritable> {             @Override             public int getPartition(Text key,                       NullWritable value, int numPartitions) {                 String[] cols = key.toString().split("\t");                 return Integer.parseInt(cols[1]) % numPartitions;             }         }         //以此 第二列，第一列 排序         class MySort implements RawComparator<Text> {             @Override             public int compare(Text o1, Text o2) {                 String suv1 = o1.toString().split("\t")[1];                 String time1 = o1.toString().split("\t")[0];                 String suv2 = o2.toString().split("\t")[1];                 String time2 = o2.toString().split("\t")[0];                 int ii = suv1.compareTo(suv2);                 if (ii != 0)                     return ii;                 else {                     return time1.compareTo(time2);                 }             }             @Override             public int compare(byte[] b1, int s1, int l1,                             byte[] b2, int s2, int l2) {                 Text key1 = new Text();                 Text key2 = new Text();                 DataInputBuffer buffer = new DataInputBuffer();                 try {                     buffer.reset(b1, s1, l1);                     key1.readFields(buffer);                     buffer.reset(b2, s2, l2);                     key2.readFields(buffer);                 } catch (IOException e) {                     throw new RuntimeException(e);                 }                 return compare(key1, key2);             }         }                  // 以第二列 值 分组         class MyComparator implements RawComparator<Text> {             @Override             public int compare(byte[] b1, int s1, int l1,                          byte[] b2, int s2,int l2) {                 Text key1 = new Text();                 Text key2 = new Text();                 DataInputBuffer buffer = new DataInputBuffer();                 try {                     buffer.reset(b1, s1, l1);                     key1.readFields(buffer);                     buffer.reset(b2, s2, l2);                     key2.readFields(buffer);                 } catch (IOException e) {                     throw new RuntimeException(e);                 }                 String str1 = key1.toString().split("\t")[1];                 String str2 = key2.toString().split("\t")[1];                 return str1.compareTo(str2);             }             @Override             public int compare(Text o1, Text o2) {                 return 0;             }         }     public static void main(String[] args) throws IOException,             InterruptedException, ClassNotFoundException {         Configuration config = new Configuration(true);         config.set("mapred.child.java.opts", "-Xmx1024m -Xms512m");         config.set("io.sort.mb", "100");         MapreduceUtil mru = new MapreduceUtil(config);         String out_path_1 = mru.applicationSpace(null);         Job job = new Job(config);         job.setNumReduceTasks(2);         job.setOutputKeyClass(Text.class);         job.setOutputValueClass(NullWritable.class);         job.setMapperClass(MyMap.class);         job.setJarByClass(MapreduceUtil.class);         job.setReducerClass(MyReducer.class);         job.setPartitionerClass(MyPartitioner.class);                  job.setGroupingComparatorClass(MyComparator.class);         job.setSortComparatorClass(MySort.class);                  FileInputFormat.setInputPaths(job, new Path("/tmp/text.txt"));         FileOutputFormat.setOutputPath(job, new Path(out_path_1));         job.waitForCompletion(true);         System.out.println(out_path_1);     }