source: sample/hadoop-0.16/tw/org/nchc/demo/DemoHBaseSink.java @ 27

/**
 * Program: DemoHBaseSink.java
 * Editor: Waue Chen 
 * From :  NCHC. Taiwn
 * Last Update Date: 07/02/2008
 * Re-code from : Cloud9: A MapReduce Library for Hadoop
 */
/*
 * Cloud9: A MapReduce Library for Hadoop
 */

package tw.org.nchc.demo;

import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapred.TableReduce;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.lib.IdentityMapper;
import org.apache.hadoop.mapred.lib.IdentityReducer;

/**
 * 
 */
public class DemoHBaseSink {

  private static class ReduceClass extends TableReduce<LongWritable, Text> {

    // this is the column we're going to be writing
    private static final Text col = new Text("default:text");

    // this map holds the columns per row
    private MapWritable map = new MapWritable();

    public void reduce(LongWritable key, Iterator<Text> values,
        OutputCollector<Text, MapWritable> output, Reporter reporter)
        throws IOException {

      // contents must be ImmutableBytesWritable
      ImmutableBytesWritable bytes = new ImmutableBytesWritable(values
          .next().getBytes());

      // populate the current row
      map.clear();
      map.put(col, bytes);

      // add the row with the key as the row id
      output.collect(new Text(key.toString()), map);
    }
  }

  private DemoHBaseSink() {
  }

  /**
   * Runs the demo.
   */
  public static void main(String[] args) throws IOException {
    String filename = "/shared/sample";

    int mapTasks = 1;
    int reduceTasks = 1;

    JobConf conf = new JobConf(DemoHBaseSink.class);
    conf.setJobName("wordcount");

    // must initialize the TableReduce before running job
    TableReduce.initJob("test", ReduceClass.class, conf);

    conf.setNumMapTasks(mapTasks);
    conf.setNumReduceTasks(reduceTasks);
    conf.setInputPath(new Path(filename));
    conf.setMapperClass(IdentityMapper.class);
    conf.setCombinerClass(IdentityReducer.class);
    conf.setReducerClass(ReduceClass.class);

    JobClient.runJob(conf);
  }
}