HBase API 操作

环境准备

HBase API 需要依赖的 pom.xml

<dependency>
	<groupId>org.apache.hbase</groupId>
	<artifactId>hbase-server</artifactId>
	<version>1.3.1</version>
</dependency>

<dependency>
	<groupId>org.apache.hbase</groupId>
	<artifactId>hbase-client</artifactId>
	<version>1.3.1</version>
</dependency>

<dependency>
	<groupId>jdk.tools</groupId>
	<artifactId>jdk.tools</artifactId>
	<version>1.8</version>
	<scope>system</scope>
	<systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>
</dependency>

获取 Configuration 对象

public static Configuration conf; static{
//使用 HBaseConfiguration 的单例方法实例化
conf = HBaseConfiguration.create(); 
//                                   自己虚拟机的ip
conf.set("hbase.zookeeper.quorum", "192.168.100.150");
conf.set("hbase.zookeeper.property.clientPort", "2181");
}

判断表是否存在

public static boolean isTableExist(String tableName) throws MasterNotRunningException, ZooKeeperConnectionException, IOException{
	//在 HBase 中管理、访问表需要先创建 HBaseAdmin 对象
	//Connection connection = ConnectionFactory.createConnection(conf);
	//HBaseAdmin admin = (HBaseAdmin) connection.getAdmin();
	HBaseAdmin admin = new HBaseAdmin(conf);
	return admin.tableExists(tableName);
}

创建表

public static void createTable(String tableName, String... columnFamily) throws MasterNotRunningException, ZooKeeperConnectionException, IOException{
	HBaseAdmin admin = new HBaseAdmin(conf);
	//判断表是否存在
	if(isTableExist(tableName)){
		System.out.println("表" + tableName + "已存在");
		//System.exit(0);
	}else{
	//创建表属性对象,表名需要转字节
	HTableDescriptor descriptor = new HTableDescriptor(TableName.valueOf(tableName));
	//创建多个列族
	for(String cf : columnFamily){
		 descriptor.addFamily(new HColumnDescriptor(cf));
	}
	//根据对表的配置，创建表
	admin.createTable(descriptor);
	System.out.println("表" + tableName + "创建成功！");
}

删除表

public static void dropTable(String tableName) throws MasterNotRunningException, ZooKeeperConnectionException, IOException{
	HBaseAdmin admin = new HBaseAdmin(conf);
	if(isTableExist(tableName)){
		admin.disableTable(tableName); 
		admin.deleteTable(tableName);
		System.out.println("表" + tableName + "删除成功！");
	}else{
		System.out.println("表" + tableName + "不存在！");
	}
}

向表中插入数据

public static void addRowData(String tableName, String rowKey, String columnFamily, String column, String value) throws IOException{
	//创建 HTable 对象
	HTable hTable = new HTable(conf, tableName);
	//向表中插入数据
	Put put = new Put(Bytes.toBytes(rowKey));
	//向 Put 对象中组装数据
	put.add(Bytes.toBytes(columnFamily), Bytes.toBytes(column), Bytes.toBytes(value));
	hTable.put(put);
	hTable.close();
	System.out.println("插入数据成功");
}

删除多行数据

public static void deleteMultiRow(String tableName, String... rows) throws IOException{ 
	HTable hTable = new HTable(conf, tableName);
	List<Delete> deleteList = new ArrayList<Delete>(); 
	for(String row : rows){
		Delete delete = new Delete(Bytes.toBytes(row)); 
		deleteList.add(delete);
	}
	hTable.delete(deleteList); hTable.close();
}

获取所有数据

public static void getAllRows(String tableName) throws IOException{ 
	HTable hTable = new HTable(conf, tableName);
	//得到用于扫描 region 的对象
	Scan scan = new Scan();
	//使用 HTable 得到 resultcanner 实现类的对象ResultScanner 	
	resultScanner = hTable.getScanner(scan); 
	for(Result result : resultScanner){
		Cell[] cells = result.rawCells(); 
		for(Cell cell : cells){
			//得到 rowkey
			System.out.println("行键:" + Bytes.toString(CellUtil.cloneRow(cell)));
			//得到列族
			System.out.println("列族" + Bytes.toString(CellUtil.cloneFamily(cell))); 
			System.out.println("列:" + Bytes.toString(CellUtil.cloneQualifier(cell))); 
			System.out.println("值:" + Bytes.toString(CellUtil.cloneValue(cell)));
		}
	}
}

获取某一行数据

public static void getRow(String tableName, String rowKey) throws IOException{ 
	HTable table = new HTable(conf, tableName);
	Get get = new Get(Bytes.toBytes(rowKey));
	//get.setMaxVersions();显示所有版本
	//get.setTimeStamp();显示指定时间戳的版本
	Result result = table.get(get);
	for(Cell cell : result.rawCells()){
		System.out.println(" 行 键 :" + Bytes.toString(result.getRow())); 
		System.out.println("列族" + Bytes.toString(CellUtil.cloneFamily(cell))); 	
		System.out.println("列:" + Bytes.toString(CellUtil.cloneQualifier(cell))); 
		System.out.println(" 值 :" + Bytes.toString(CellUtil.cloneValue(cell))); 
		System.out.println("时间戳:" + cell.getTimestamp());
	}
}

获取某一行指定“列族:列”的数据

public static void getRowQualifier(String tableName, String rowKey, String family, String qualifier) throws IOException{
	HTable table = new HTable(conf, tableName); 
	Get get = new Get(Bytes.toBytes(rowKey));
	get.addColumn(Bytes.toBytes(family), Bytes.toBytes(qualifier)); 
	Result result = table.get(get);
	for(Cell cell : result.rawCells()){
		System.out.println(" 行 键 :" + Bytes.toString(result.getRow())); 
		System.out.println("列族" + Bytes.toString(CellUtil.cloneFamily(cell))); 
		System.out.println("列:" + Bytes.toString(CellUtil.cloneQualifier(cell))); 
		System.out.println("值:" + Bytes.toString(CellUtil.cloneValue(cell)));
	}
}

MapReduce
通过 HBase 的相关 JavaAPI，我们可以实现伴随 HBase 操作的 MapReduce 过程，比如使用MapReduce 将数据从本地文件系统导入到 HBase 的表中，比如我们从 HBase 中读取一些原始数据后使用 MapReduce 做数据分析。

HBase-MapReduce
查看 HBase 的 MapReduce 任务的执行
$ bin/hbase mapredcp