文章內容

HBase Java API使用操作例子

發布時間: 2012/9/5 16:56:21

通過對HBase API的使用，下面例子舉例了常見對HBase的操作，如下所示：

package net.linuxidc.www;
-

import org.apache.Hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.BatchUpdate;

public class HBaseDBDao {

    //定義配置對象HBaseConfiguration
    static HBaseConfiguration cfg =null;
    static {
        Configuration configuration = new Configuration();
        cfg = new HBaseConfiguration(configuration);
    }

    //創建一張表，指定表名，列族
    public static void createTable(String tableName,String columnFarily)throws Exception{
        HBaseAdmin admin = new HBaseAdmin(cfg);
        if(admin.tableExists(tableName)){
            System.out.println(tableName+"不存在！");
            System.exit(0);
        }else{
            HTableDescriptor tableDesc = new HTableDescriptor(tableName);
            tableDesc.addFamily(new HColumnDescriptor(columnFarily+":"));
            System.out.println("創建表成功！");
        }
    }

    //添加數據，通過HTable。和BatchUpdate為已經存在的表添加數據data
    public static void addData(String tableName,String row,String columnFamily,String column,String data)throws Exception{
        HTable table = new HTable(cfg,tableName);
        BatchUpdate update = new BatchUpdate(row);
        update.put(columnFamily+":"+column, data.getBytes());
        table.commit(update);
        System.out.println("添加成功！");
    }

    //顯示所有數據，通過HTable Scan類獲取已有表的信息
    public static void getAllData(String tableName)throws Exception{
        HTable table = new HTable(cfg,tableName);
        Scan scan = new Scan();
        ResultScanner rs = table.getScanner(scan);
        for(Result r:rs){
            for(KeyValue kv:r.raw()){
                System.out.println(new String(kv.getColumn())+new String(kv.getValue()));
            }
        }
    }

    //測試函數
    public static void main(String[] args){
        try{
            String tableName = "student";
            HBaseDBDao.createTable(tableName, "c1");
            HBaseDBDao.addData(tableName, "row1", "c1", "1", "this is row 1 column c1:c1");
            HBaseDBDao.getAllData(tableName);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}