学步园

前面介绍了HBase的常用API并给出了实例：HBase之Java API

为了便于以后使用，把对HBase表的常见CRUD操作，封装在一个类HBaseUtil里面，实现为：

import java.io.IOException;
import java.util.HashMap;

import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.client.Put;
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.util.Bytes;

public class HBaseUtil {
  
	
	//禁用表
	public void disableTable(HBaseAdmin admin, String table)  {
		try {
			admin.disableTable(table);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
  
	
	//删除表
	public void dropTable(HBaseAdmin admin, String tableName)
			{
		if (existsTable(admin, tableName)) {
			disableTable(admin, tableName);
			try {
				admin.deleteTable(tableName);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
  
	
	//判定表是否存在
	public static boolean existsTable(HBaseAdmin admin, String tableName) {
		try {
			return admin.tableExists(tableName.getBytes());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return false;
		}
	}

	// 创建数据库
	public static void createTable(HBaseAdmin ha, String tableName, String cf) {
		HTableDescriptor hd = new HTableDescriptor(tableName);
		HColumnDescriptor hc = new HColumnDescriptor(cf);
	//	hc.setMaxVersions(10);
		hd.addFamily(hc);
		try {
			ha.createTable(hd);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public static Result getValues(HTableInterface htable, String rowkey,
			String cf) {
		Result result = null;
		Get get = new Get(rowkey.getBytes());
		get.addFamily(cf.getBytes());
		try {
			result = htable.get(get);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return result;
	}

	// 插入hbase中获得数据，傳入表名tableName,行键rowkey,列族cf,列名column,得到值value.
	public static String getValue(HTableInterface htable, 
			String rowkey, String cf, String column) {
		Get get = new Get(rowkey.getBytes());
		get.addColumn(cf.getBytes(), column.getBytes());
		String createTime = null;
		try {
			Result result = htable.get(get);
			if (result.value() != null) {
				createTime = new String(result.value());
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return createTime;
	}

	// 插入數據到Hbase中，傳入表名tableName,行键rowkey,列族cf,列名column,值value.
	public static void putToHBase(HTableInterface htable, 
			String rowkey, String cf, String column, String value) {

		Put put = new Put(rowkey.getBytes());
		put.add(cf.getBytes(), column.getBytes(), value.getBytes());
		try {
			htable.put(put);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public static void putOVC(HTableInterface htable,String rowkey, String cf,String column,int value,String day){
        // 得到day的时间戳
		Long ts = DateFormatUtil.formatStringTimeToLong(day);
		Put put=new Put(Bytes.toBytes(rowkey));
        // put.add(cf,column,timestamp,value)
		put.add(Bytes.toBytes(cf),Bytes.toBytes(column),ts,Bytes.toBytes(value+""));
		try {
			htable.put(put);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public static void scanOVC( HTableInterface htable, String cf,String colum,String day,HashMap<String,Integer> sumDevice_map)
			throws IOException {	
		Long timeStamp = DateFormatUtil.formatStringTimeToLong(day)-86400000;
		Scan scan = new Scan();
		scan.setTimeStamp(timeStamp); 
		scan.addColumn(Bytes.toBytes(cf), Bytes.toBytes(colum));
		ResultScanner scanner = htable.getScanner(scan);
		for(Result res:scanner){
			KeyValue[] keyvalue = res.raw();
			for (KeyValue kv : keyvalue) {
				sumDevice_map.put(new String(kv.getRow()), Integer.parseInt(new String(kv.getValue())));
			}
		}
		scanner.close();
	}	
}