[Hadoop]Java access HBase

編譯及執行方式請依照Hadoop編譯執行方式來操作

CreateTable(執行時需傳入tablename及至少一個的column family參數)

import java.io.IOException;

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.client.HBaseAdmin;
import org.apache.hadoop.util.GenericOptionsParser;

public class CreateTable
{
	public static void createHBaseTable(String [] str) throws IOException
	{
		String tablename = str[0];
		// HTableDescriptor 用來描述table的屬性
    		HTableDescriptor htd = new HTableDescriptor(tablename);
		for(int i=1; i < str.length ; i++)
		{
    			// HTableDescriptor 透過 add() 方法來加入Column family
    			htd.addFamily(new HColumnDescriptor(str[i]));
		}
    		// HBaseConfiguration 能接收 hbase-site.xml 的設定值
    		HBaseConfiguration config = new HBaseConfiguration();
    		// 檔案的操作則使用 HBaseAdmin
    		HBaseAdmin admin = new HBaseAdmin(config);
		//檢查
		if (admin.tableExists(tablename))
		{
     			 System.out.println("Table: " + tablename + "Existed.");
    	}
		else
		{
      			// 建立
      			admin.createTable(htd);
      			System.out.println( tablename + " created.");
   		}
	}
	public static void main(String [] argv) throws IOException
	{
		System.out.println("create table:"+ argv[0]);
		createHBaseTable(argv);	
	}
}

GetColumn(執行時傳入tablename、rowkey、family、column)

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.util.GenericOptionsParser;

public class GetColumn
{
	public static String getColumn(String tablename,String row,String family,String column)
	{
		HBaseConfiguration conf = new HBaseConfiguration();
		String ret = "";
		try
		{
				HTable table = new HTable(conf, Bytes.toBytes(tablename));
      			Get g = new Get(Bytes.toBytes(row));
      			Result rowResult = table.get(g);
      			ret = Bytes.toString(rowResult.getValue(Bytes.toBytes(family + ":" + column)));
      			table.close();

		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
		return ret;
	}
	public static void main(String [] argv)throws IOException
	{
		System.out.println(getColumn(argv[0],argv[1],argv[2],argv[3]));	
	}
}

ScanColumn(執行時傳入tablename、family、column)

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
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.util.Bytes;
import org.apache.hadoop.util.GenericOptionsParser;

public class ScanColumn
{
	public static void scanColumn(String tablename,String family,String column)
	{
		HBaseConfiguration conf = new HBaseConfiguration();
		try
		{
			HTable table = new HTable(conf, Bytes.toBytes(tablename));
			ResultScanner scanner = table.getScanner(Bytes.toBytes(family));
			int i=1;
			for (Result rowResult : scanner)
			{
        			byte[] by = rowResult.getValue(Bytes.toBytes(family), Bytes.toBytes(column));
        			String str = Bytes.toString(by);
        			System.out.println("row " + i + " is \"" + str + "\"");
        			i++;
      		}
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	public static void main(String [] argv)
	{
		scanColumn(argv[0],argv[1],argv[2]);
	}
}

PutData(執行時傳入tablename、rowkey、family、column、value)

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.util.GenericOptionsParser;

public class PutData
{
	public static void putData(String tablename,String row,String family,String column,String value)
	throws IOException
	{
		// HBaseConfiguration 能接收 hbase-site.xml 的設定值
		HBaseConfiguration config = new HBaseConfiguration();
    	HTable table = new HTable(config, tablename);

		byte[] brow = Bytes.toBytes(row);
		byte[] bfamily = Bytes.toBytes(family);
    	byte[] bcolumn = Bytes.toBytes(column);
    	byte[] bvalue = Bytes.toBytes(value);

		Put p = new Put(brow);
		p.add(bfamily, bcolumn, bvalue);
    	table.put(p);
		System.out.println("輸入資料："+value+"  至Table："+tablename+"  "+family+":"+column);
	    table.close();

	}
	public static void main(String [] argv)throws IOException
	{
		putData(argv[0],argv[1],argv[2],argv[3],argv[4]);
	}
}

DropTable(執行時輸入tablename)

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.util.GenericOptionsParser;

public class DropTable
{
	static void drop(String tablename)
	{
		HBaseConfiguration conf = new HBaseConfiguration();
   		HBaseAdmin admin;
		try
		{
			admin = new HBaseAdmin(conf);
			if(admin.tableExists(tablename))
			{
				admin.disableTable(tablename);
        		admin.deleteTable(tablename);
        		System.out.println("Droped the table [" + tablename + "]");
			}
			else {System.out.println("Table [" + tablename + "] was not found!");}
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
	}
	public static void main (String [] argv)
	{
		drop(argv[0]);
	}
}