用MapReduce排序Hbase表中的成绩的代码

下面是用 MapReduce 排序 Hbase 表中的成绩的示例代码：

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;

public class HBaseSort {

  public static class HBaseMapper extends TableMapper<Text, IntWritable> {
    public static final byte[] CF = "cf".getBytes();
    public static final byte[] ATTR1 = "grade".getBytes();

    private final IntWritable grade = new IntWritable();
    private final Text row = new Text();

    @Override
    public void map(ImmutableBytesWritable row, Result value, Context context) throws IOException, InterruptedException {
      // 获取行键
      String rowKey = new String(row.get());
      this.row.set(rowKey);

      // 获取成绩
      byte[] bGrade = value.getValue(CF, ATTR1);
      int intGrade = Bytes.toInt(bGrade);
      grade.set(intGrade);

      // 输出行键和成绩
      context.write(row, grade);
    }
  }

  public static class HBaseReducer extends TableReducer<Text, IntWritable, ImmutableBytesWritable> {
    public static final byte[] CF = "cf".getBytes();
    public static final byte[] ATTR1 = "grade".getBytes();

    @Override
    public void reduce(Text row, Iterable<IntWritable> grades, Context context) throws IOException, InterruptedException {
      // 遍历成绩列表，将成绩写入 HBase 表
      for (IntWritable grade : grades) {
        Put put = new Put(Bytes.toBytes(row.toString()));
        put.addColumn(CF, ATTR1, Bytes.toBytes(grade.get()));
        context.write(new ImmutableBytesWritable(Bytes.toBytes(row.toString())), put);
      }
    }
  }

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