source: sample/HBaseRecord2.java @ 11

/**
 * Program: HBaseRecord.java
 * Editor: Waue Chen 
 * From :  NCHC. Taiwn
 * Last Update Date: 06/13/2008
 */

/**
 * Purpose : 
 *  1.Auto generate HTable 
 *  2.Parse your record and then store in HBase.
 * 
 * HowToUse : 
 *  Make sure Hadoop file system and Hbase are running correctly.
 *  1. put test.txt in t1 directory which content is 
  ---------------
  name:locate:years 
  waue:taiwan:1981
  shellon:taiwan:1981
  ---------------
 *  2. hadoop_root/$ bin/hadoop dfs -put t1 t1
 *  3. hbase_root/$ bin/hbase shell
 *  4. hql > create table t1_table("person");
 *  5. Come to Eclipse and run this code, and we will let database as that 
  t1_table -> person
    ----------------
    |  name | locate | years |
    | waue  | taiwan | 1981 |
    | shellon | taiwan | 1981 |
    ----------------
 * Check Result:
 *  Go to hbase console, type : 
 *    hql > select * from t1_table; 
08/06/06 12:20:48 INFO hbase.HTable: Creating scanner over t1_table starting at key 
+-------------------------+-------------------------+-------------------------+
| Row                     | Column                  | Cell                    |
+-------------------------+-------------------------+-------------------------+
| 0                       | person:locate           | locate                  |
+-------------------------+-------------------------+-------------------------+
| 0                       | person:name             | name                    |
+-------------------------+-------------------------+-------------------------+
| 0                       | person:years            | years                   |
+-------------------------+-------------------------+-------------------------+
| 19                      | person:locate           | taiwan                  |
+-------------------------+-------------------------+-------------------------+
| 19                      | person:name             | waue                    |
+-------------------------+-------------------------+-------------------------+
| 19                      | person:years            | 1981                    |
+-------------------------+-------------------------+-------------------------+
| 36                      | person:locate           | taiwan                  |
+-------------------------+-------------------------+-------------------------+
| 36                      | person:name             | shellon                 |
+-------------------------+-------------------------+-------------------------+
| 36                      | person:years            | 1981                    |
+-------------------------+-------------------------+-------------------------+
3 row(s) in set. (0.04 sec)
 */




package tw.org.nchc.code;

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 HBaseRecord2 {

  /* Denify parameter */
  // one column family: person; three column qualifier: name,locate,years
  final String colstr;
  // Hbase table name
  static String[] col;
  String Table_Name = "Record1";
  //split character
  static String sp = ":";
  // file path in hadoop file system (not phisical file system)
  String file_path = "/user/waue/t1";



  public HBaseRecord2(){
    colstr ="person:name,locate,years";
  }
  public HBaseRecord2(String str){
    colstr = str; 
  }

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

    // Column id is created dymanically, 
    private static final Text col_name = new Text(baseId1);
    private static final Text col_local = new Text(baseId2);
    private static final Text col_year = new Text(baseId3);
    
    // this map holds the columns per row
    private MapWritable map = new MapWritable();  
    
    // on this sample, map is nonuse, we use reduce to handle
    public void reduce(LongWritable key, Iterator<Text> values,
        OutputCollector<Text, MapWritable> output, Reporter reporter)
        throws IOException {

      // values.next().getByte() can get value and transfer to byte form, there is an other way that let decode()
      // to substitude getByte() 
      String stro = new String(values.next().getBytes());
      String str[] = stro.split(sp);
      byte b_local[] = str[0].getBytes();
      byte b_name[] = str[1].getBytes();
      byte b_year[] = str[2].getBytes();
      
      // contents must be ImmutableBytesWritable
      ImmutableBytesWritable w_local = new ImmutableBytesWritable( b_local);
      ImmutableBytesWritable w_name = new ImmutableBytesWritable( b_name );
      ImmutableBytesWritable w_year = new ImmutableBytesWritable( b_year );

      // populate the current row
      map.clear();
      map.put(col_name, w_local);
      map.put(col_local, w_name);
      map.put(col_year, w_year);

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

  /**
   * Runs the demo.
   */
  public static void main(String[] args) throws IOException {
    // parse colstr to split column family and column qualify
    HBaseRecord2 work = new HBaseRecord2();
    
    String tmp[] = work.colstr.split(":");
    String Column_Family = tmp[0]+":";
    String CF[] = {Column_Family};
    String CQ[] = tmp[2].split(",");
    // check whether create table or not , we don't admit \ 
    // the same name but different structure
    
    BuildHTable build_table = new BuildHTable(work.Table_Name,CF);
    if (!build_table.checkTableExist(work.Table_Name)) {
      if (!build_table.createTable()) {
        System.out.println("create table error !");
      }
    }else{
      System.out.println("Table \"" + work.Table_Name +"\" has already existed !");
    }   

    JobConf conf = new JobConf(HBaseRecord2.class);
    int mapTasks = 1;
    int reduceTasks = 1;
    //Job name; you can modify to any you like  
    conf.setJobName("NCHC_PersonDataBase");

    // Hbase table name must be correct , in our profile is t1_table
    TableReduce.initJob(work.Table_Name, ReduceClass.class, conf);
    
    // below are map-reduce profile
    conf.setNumMapTasks(mapTasks);
    conf.setNumReduceTasks(reduceTasks);
    conf.setInputPath(new Path(work.file_path));
    conf.setMapperClass(IdentityMapper.class);
    conf.setCombinerClass(IdentityReducer.class);
    conf.setReducerClass(ReduceClass.class);
    JobClient.runJob(conf);
  }
}