Hbase操作表和Java API_列出hbase中默认库的所有表名javaapi-优快云博客

本文链接：https://blog.youkuaiyun.com/weidong22/article/details/79086175

Hbasel列出表
使用list命令可列出所有表

hbase(main):001:0 > list

使用Java API列出表

下面给出的是使用Java API程序列出所有HBase中表的列表。

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;


public class ListTables {

   public static void main(String args[])throws MasterNotRunningException, IOException{

   // Instantiating a configuration class
   Configuration conf = HBaseConfiguration.create();

   // Instantiating HBaseAdmin class
   HBaseAdmin admin = new HBaseAdmin(conf);

   // Getting all the list of tables using HBaseAdmin object
   HTableDescriptor[] tableDescriptor =admin.listTables();

   // printing all the table names.
   for (int i=0; i<tableDescriptor.length;i++ ){
      System.out.println(tableDescriptor[i].getNameAsString());
   }

   }
 }

HBase禁用表
hbase禁用表使用 disable命令：

disable '表名'

使用is_disabled命令查看表是否被禁用，返回true或者false

hbase> is_disabled 'table name'

禁用所有表：disable_all

hbase> disable_all 'r.*'  禁用所有和 r.* 匹配的表

输出：

hbase(main):002:0> disable_all 'raj.*'
raja
rajani
rajendra
rajesh
raju
Disable the above 5 tables (y/n)?
y
5 tables successfully disabled

禁用表使用Java API

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;

public class DisableTable{

   public static void main(String args[]) throws MasterNotRunningException, IOException{

   // Instantiating configuration class
   Configuration conf = HBaseConfiguration.create();

   // Instantiating HBaseAdmin class
   HBaseAdmin admin = new HBaseAdmin(conf);

   // Verifying weather the table is disabled
   Boolean bool = admin.isTableDisabled("emp");
   System.out.println(bool);

   // Disabling the table using HBaseAdmin object
   if(!bool){
      admin.disableTable("emp");
      System.out.println("Table disabled");
   }

   }
}

HBase启用表
启用表：enable

hbase(main):005:0> enable 'emp'
0 row(s) in 0.4580 seconds

判断表是否被启用：is_enabled

hbase(main):031:0> is_enabled 'emp'
true
0 row(s) in 0.0440 seconds

使用Java API启用表

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;

public class EnableTable{

   public static void main(String args[]) throws MasterNotRunningException, IOException{

   // Instantiating configuration class
   Configuration conf = HBaseConfiguration.create();

   // Instantiating HBaseAdmin class
   HBaseAdmin admin = new HBaseAdmin(conf);

   // Verifying weather the table is disabled
   Boolean bool = admin.isTableEnabled("emp");
   System.out.println(bool);

   // Disabling the table using HBaseAdmin object
   if(!bool){
      admin.enableTable("emp");
      System.out.println("Table Enabled");
   }

   }
}

HBase表描述和修改

hbase(main):002:0> describe 'coupon:coupon_member'
Table coupon:coupon_member is ENABLED                                                                                                                                                                                                                                         
coupon:coupon_member                                                                                                                                                                                                                                                          
COLUMN FAMILIES DESCRIPTION                                                                                                                                                                                                                                                   
{NAME => 'info', BLOOMFILTER => 'ROW', VERSIONS => '1', IN_MEMORY => 'false', KEEP_DELETED_CELLS => 'FALSE', DATA_BLOCK_ENCODING => 'NONE', TTL => 'FOREVER', COMPRESSION => 'NONE', MIN_VERSIONS => '0', BLOCKCACHE => 'true', BLOCKSIZE => '65536', REPLICATION_SCOPE => '0'
}                                                                                                                                                                                                                                                                             
1 row(s) in 0.1830 seconds

修改

alter用于更改现有表的命令。使用此命令可以更改列族的单元，设定最大数量和删除表范围运算符，并从表中删除列家族。

更改列族单元格的最大数目
下面给出的语法来改变列家族单元的最大数目。

hbase> alter 't1', NAME => 'f1', VERSIONS => 5
在下面的例子中，单元的最大数目设置为5。

hbase(main):003:0> alter 'emp', NAME => 'personal data', VERSIONS => 5
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.3050 seconds

表范围运算符
使用alter，可以设置和删除表范围，运算符，如MAX_FILESIZE，READONLY，MEMSTORE_FLUSHSIZE，DEFERRED_LOG_FLUSH等。

设置只读
下面给出的是语法，是用以设置表为只读。

hbase>alter ‘t1’, READONLY(option)
在下面的例子中，我们已经设置表emp为只读。

hbase(main):006:0> alter 'emp', READONLY
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.2140 seconds

删除表范围运算符
也可以删除表范围运算。下面给出的是语法，从emp表中删除“MAX_FILESIZE”。

hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'MAX_FILESIZE'

删除列族
使用alter，也可以删除列族。下面给出的是使用alter删除列族的语法。

hbase> alter ‘ table name ’, ‘delete’ => ‘ column family ’

下面给出的是一个例子，从“emp”表中删除列族。

假设在HBase中有一个employee表。它包含以下数据：

hbase(main):006:0> scan 'employee'

         ROW                   COLUMN+CELL
row1 column=personal:city, timestamp=1418193767, value=hyderabad

row1 column=personal:name, timestamp=1418193806767, value=raju

row1 column=professional:designation, timestamp=1418193767, value=manager

row1 column=professional:salary, timestamp=1418193806767, value=50000

1 row(s) in 0.0160 seconds

现在使用alter命令删除指定的 professional 列族。

hbase(main):007:0> alter 'employee','delete'=>'professional'
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.2380 seconds

现在验证该表中变更后的数据。观察列族“professional”也没有了，因为前面已经被删除了。

hbase(main):003:0> scan 'employee'
 ROW             COLUMN+CELL
row1 column=personal:city, timestamp=14181936767, value=hyderabad

row1 column=personal:name, timestamp=1418193806767, value=raju

1 row(s) in 0.0830 seconds

使用Java API添加一列族

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;

public class AddColoumn{

   public static void main(String args[]) throws MasterNotRunningException, IOException{

      // Instantiating configuration class.
      Configuration conf = HBaseConfiguration.create();

      // Instantiating HBaseAdmin class.
      HBaseAdmin admin = new HBaseAdmin(conf);

      // Instantiating columnDescriptor class
      HColumnDescriptor columnDescriptor = new HColumnDescriptor("contactDetails");

      // Adding column family
      admin.addColumn("employee", columnDescriptor);
      System.out.println("coloumn added");
   }
}

使用Java API删除列族

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;

public class DeleteColoumn{

   public static void main(String args[]) throws MasterNotRunningException, IOException{

      // Instantiating configuration class.
      Configuration conf = HBaseConfiguration.create();

      // Instantiating HBaseAdmin class.
      HBaseAdmin admin = new HBaseAdmin(conf);

      // Deleting a column family
      admin.deleteColumn("employee","contactDetails");
      System.out.println("coloumn deleted"); 
   }
}