HBase Java 控制-1

开始接触HBase，捣鼓了半天总算使用Java在HBase上成功创建了一个表。记录这个过程，供新手参考。

1. 环境

      HBase使用版本0.94.5.

      下载地址: hbase-0.94.5.tar.gz

       配置方法：

      这里使用standalone(单机模拟方式)模式

      java 版本: 1.6

      操作系统：centos 5.

2. 编写步骤

     创建Example_1.java文件

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;

public class Example_1
{
	private Configuration conf=null;
	
	public Example_1()
	{
		conf=HBaseConfiguration.create();//需要读取HBase-site.xml配置文件
	}
	/**
	 * 创建表操作
	 * @throws IOException
	 */
	public void createTable(String tablename, String[] cfs) throws IOException {
	    HBaseAdmin admin = new HBaseAdmin(conf);
	    if (admin.tableExists(tablename)) {
	        System.out.println("表已经存在");
	    }
	    else {
	        HTableDescriptor tableDesc = new HTableDescriptor(tablename);
	        for (int i = 0; i < cfs.length; i++) {
	            tableDesc.addFamily(new HColumnDescriptor(cfs[i]));
	        }
	        admin.createTable(tableDesc);
	        System.out.println("表创建成功！");
	    }
	    admin.close();
	}
	public static void main(String args[]) throws IOException
	{
		Example_1 e=new Example_1();
		
		String tablename="test";
		String columnFamilys[]={"cf1","cf2","cf3"};
		e.createTable(tablename, columnFamilys);
	}
}

        编译该文件使用的命令为:

HBASE_HOME=path-to-hbase-directory

javac -cp $HBASE_HOME/*:$HBASE_HOME/lib/* Example_1.java

4. 运行

    运行时，需要指定HBase配置。简单的方法是将HBase-site.xml文件拷贝到程序相同的目录下。也可以通过conf.set(name,value)方式写入代码中，但这种方式不太灵活.

       HBase-site.xml

      

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<configuration>
	<property>
		<name>hbase.rootdir</name>
		<value>file:///home/hbase/hbase-0.94.5/hbase_data</value>
	</property>
	<property>
		<name>hbase.zookeeper.property.dataDir</name>
		<value>file:///home/hbase/hbase-0.94.5/zookeeper_data</value>
	</property>
	<property>
		<name>hbase.zookeeper.property.clientPort</name>
		<value>2181</value>
	</property>
	<property>
		<name>hbase.zookeeper.quorum</name>
		<value>hadoop.master</value>
	</property>
	<property>
		<name>hbase.cluster.distributed</name>
		<value>false</value>
	</property>
</configuration>

       运行需要指定各个jar包。

     

HBASE_HOME=path-to-hbase-directory

java -cp .:$HBASE_HOME/*:$HBASE_HOME/lib/* Example_1

5. 结果

   代码运行成功后，会创建表test. 包括三个columnFamily: 'cf1', 'cf2', 'cf3'.

       使用hbase shell检查：

      

[hbase@hadoop hbase-example-1]$ hbase shell
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 0.94.5, r1443843, Fri Feb  8 05:51:25 UTC 2013
hbase(main):003:0> describe 'test'
DESCRIPTION                                                                                                                        ENABLED                                                                
 {NAME => 'test', FAMILIES => [{NAME => 'cf1', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '0', VER true                                                                   
 SIONS => '3', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => '2147483647', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536                                                                        
 ', IN_MEMORY => 'false', ENCODE_ON_DISK => 'true', BLOCKCACHE => 'true'}, {NAME => 'cf2', DATA_BLOCK_ENCODING => 'NONE', BLOOMFIL                                                                        
 TER => 'NONE', REPLICATION_SCOPE => '0', VERSIONS => '3', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => '2147483647', KEEP_D                                                                        
 ELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', ENCODE_ON_DISK => 'true', BLOCKCACHE => 'true'}, {NAME => 'c                                                                        
 f3', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '0', VERSIONS => '3', COMPRESSION => 'NONE', MIN_                                                                        
 VERSIONS => '0', TTL => '2147483647', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', ENCODE_ON_DISK =                                                                        
 > 'true', BLOCKCACHE => 'true'}]}                                                                                                                                                                        
1 row(s) in 0.0130 seconds

更多Java控制HBase的总结将不断更新.