HBase Java API编程实践

1.HBase常用的API

1.org.apache.hadoop.hbase.client.HBaseAdmin

        HBaseAdmin类主要用于管理HBase数据库的表信息，包括创建或删除表、列出表项、使表有效或无效、添加或删除表的列族成员、检查HBase的运行状态等。HBaseAdmin类的主要方法如下所示。

 2.org.apache.hadoop.hbase.HBaseConfiguration

        该类主要用于管理HBase的配置信息。HBaseConfiguration主要方法如下表所示。

3. org.apache.hadoop.hbase.client.HTable

        该类用于与HBase进行通信。如果多个线程对一个HTable对象进行put或者delete操作的话，则写缓冲器可能会崩溃。因此，在多线程环境下，建议使用HTablePool。HTable类的主要方法如下表所示。

4.org.apache.hadoop.hbase.HTableDescriptor

         HTableDescriptor包含了HBase中表格的详细信息，如表中的列族、该表的类型(-ROOT-,.META.)、该表是否只读、MemStore的最大空间、Region什么时候应该分裂等。该类的主要方法如下表所示。

 5.org.apache.hadoop.hbase.HColumnDescriptor

        HColumnDescriptor包含了列族的详细信息，如列族的版本号、压缩设置等。HColumnDescriptor通常在添加列族或者创建表的时候使用。列族一旦建立就不能被修改，只能通过删除列族，再创建新的列族来间接修改列族。一旦列族被删除了，该列族包含的数据也随之被删除。HColumnDescriptor类主要方法如下表所示。

6.org.apache.hadoop.hbase.client.Put

        该类用来对单元格执行添加数据操作。Put类的主要方法如下表所示。

 7.org.apache.hadoop.hbase.client.Get

        该类用来获取单行的信息。Get类的主要方法如下表所示。

8.org.apache.hadoop.hbase.client.Result

        该类用于存放Get或Scan操作后的查询结果，并以的格式存储在map结构中，该类不是线程安全的。Result类的主要方法如下表所示。

 

 

9.org.apache.hadoop.hbase.client.ResultScanner

        该类为客户端获取值的接口，该接口的主要方法如下表所示。

10.org.apache.hadoop.hbase.client.Scan

        可以利用Scan类来限定需要查找的数据，如限定版本号、起始行号、列族、列限定符、返回数量的上限等。该类的主要方法如下表所示。

2.编程实践

        本文的实践主要是建表，插入数据，删除数据，查询等功能。以下根据不同功能编写不同的类。目标就是建立一个如下所示的表。

name	Info		score
	Id	grade	Math	Chinese	English
Carson	10101	4	97	90	80
Amy	10102	3	90	70	89
Bob	10103	5	95	99	86
Jason	10104	3	88	93	95

        具体实现类如下所示。

1.创建类，主要用于创建表。

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 java.io.IOException;

/**
 * @author carson0408
 * 该类主要用于建表，涉及到配置的读取，以及建表
 */
public class CreateDemo {
    /**
     * 创建表
     * @param tableName
     * @param columnFamily
     * @throws IOException
     */
    public static void create(String tableName,String[] columnFamily) throws IOException {
        //利用HBaseConfiguration的静态方法create()，生成Configuration对象
        Configuration cfg =  HBaseConfiguration.create();
        //利用Configuration对象生成HBaseAdmin对象，主要用于管理HBase数据库的表信息，包括创建或删除表
        HBaseAdmin admin = new HBaseAdmin(cfg);

        //创建表，根据数据库的建表习惯，都是先判断表是否存在，如果存在先删除后建表,但是HBase中删除表之前需要使表先无效再删除
        if(admin.tableExists(tableName)){
            admin.disableTable(tableName);
            admin.deleteTable(tableName);
        }

        //创建表，HBaseAdmin对象的createTable(HTableDescriptor desc)方法创建表，输入参数是HTableDescriptor对象
        //HTableDescriptor对象则是包含了HBase中表格的详细信息，通过tableName作为参数建立对象，并将列族添加进去。
        //添加列族时通过HTableDescriptor对象的addFamily(HColumnDescriptor hcd)添加的
        //HColumnDescriptor对象则是以列族名作为参数创建的。
        HTableDescriptor htd = new HTableDescriptor(tableName);
        for(String column:columnFamily){
            htd.addFamily(new HColumnDescriptor(column));
        }
        admin.createTable(htd);
    }
}

 2.插入数据类

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 java.io.IOException;

public class InsertDemo {

    /**
     *
     * @param tableName
     * @param row
     * @param columnFamily
     * @param column
     * @param data
     * @throws IOException
     */
    public static void insertData(String tableName,String row,String columnFamily,String column,String data) throws IOException {
        Configuration cfg = HBaseConfiguration.create();
        //HTable对象用于与HBase进行通信。
        HTable table = new HTable(cfg,tableName);
        //通过Put对象为已存在的表添加数据
        Put put = new Put(row.getBytes());
        if(column==null)//判断列限定符是否为空，如果为空，则直接添加列数据
            put.add(columnFamily.getBytes(),null,data.getBytes());
        else
            put.add(columnFamily.getBytes(),column.getBytes(),data.getBytes());
        //table对象的put输入参数是put对象，而put对象则表示每一单元格数据。
        table.put(put);


    }
}

3.查询数据类

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 java.io.IOException;

/**
 * 该类用于获取数据
 */
public class GetDemo {

    public static void getData(String tableName,String row,String columnFamily,String column) throws IOException {
        Configuration cfg = HBaseConfiguration.create();
        HTable table = new HTable(cfg,tableName);
        //根据行键建立Get对象
        Get get = new Get(row.getBytes());
        //通过get对象获取Result对象，Result对象表示一行的记录
        Result result = table.get(get);
        //再通过列族和列来确定单元格的数据。
        System.out.println(new String(result.getValue(columnFamily.getBytes(),column==null?null:column.getBytes())));
    }
}

4.删除数据类

 

5.测试类

a.首先建表，代码如下所示

import com.carson.HBase.create.CreateDemo;
import com.carson.HBase.insertData.InsertDemo;

import java.io.IOException;

public class TestDemo {

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

        //先创建一个scores的表，列族有info，score
        String[] columnFamily = {"info","score"};
        String tableName = "scores";
        CreateDemo.create(tableName,columnFamily);


        //插入数据
        //插入Carson的信息和成绩
        InsertDemo.insertData("scores","Carson","info","Id","10101");
        InsertDemo.insertData("scores","Carson","info","grade","4");
        InsertDemo.insertData("scores","Carson","score","Math","97");
        InsertDemo.insertData("scores","Carson","score","Chinese","90");
        InsertDemo.insertData("scores","Carson","score","English","80");
        //插入Amy的信息和成绩
        InsertDemo.insertData("scores","Amy","info","Id","10102");
        InsertDemo.insertData("scores","Amy","info","grade","3");
        InsertDemo.insertData("scores","Amy","score","Math","90");
        InsertDemo.insertData("scores","Amy","score","Chinese","70");
        InsertDemo.insertData("scores","Amy","score","English","89");
        //Bob
        InsertDemo.insertData("scores","Bob","info","Id","10103");
        InsertDemo.insertData("scores","Bob","info","grade","5");
        InsertDemo.insertData("scores","Bob","score","Math","95");
        InsertDemo.insertData("scores","Bob","score","Chinese","99");
        InsertDemo.insertData("scores","Bob","score","English","86");
        //Jason
        InsertDemo.insertData("scores","Jason","info","Id","10104");
        InsertDemo.insertData("scores","Jason","info","grade","3");
        InsertDemo.insertData("scores","Jason","score","Math","88");
        InsertDemo.insertData("scores","Jason","score","Chinese","93");
        InsertDemo.insertData("scores","Jason","score","English","95");



    }
}

运行之后，在HBase shell中输入scan "scores"，得到如下结果，可以看出，建立了之前说明的表，而且是根据行键的字典序排列的，与插入顺序无关。

                   

 

b.查询数据

import com.carson.HBase.create.CreateDemo;
import com.carson.HBase.getData.GetDemo;
import com.carson.HBase.insertData.InsertDemo;

import java.io.IOException;

public class TestDemo {

    public static void main(String[] args) throws IOException {
/**
        //先创建一个scores的表，列族有info，score
        String[] columnFamily = {"info","score"};
        String tableName = "scores";
        CreateDemo.create(tableName,columnFamily);


        //插入数据
        //插入Carson的信息和成绩
        InsertDemo.insertData("scores","Carson","info","Id","10101");
        InsertDemo.insertData("scores","Carson","info","grade","4");
        InsertDemo.insertData("scores","Carson","score","Math","97");
        InsertDemo.insertData("scores","Carson","score","Chinese","90");
        InsertDemo.insertData("scores","Carson","score","English","80");
        //插入Amy的信息和成绩
        InsertDemo.insertData("scores","Amy","info","Id","10102");
        InsertDemo.insertData("scores","Amy","info","grade","3");
        InsertDemo.insertData("scores","Amy","score","Math","90");
        InsertDemo.insertData("scores","Amy","score","Chinese","70");
        InsertDemo.insertData("scores","Amy","score","English","89");
        //Bob
        InsertDemo.insertData("scores","Bob","info","Id","10103");
        InsertDemo.insertData("scores","Bob","info","grade","5");
        InsertDemo.insertData("scores","Bob","score","Math","95");
        InsertDemo.insertData("scores","Bob","score","Chinese","99");
        InsertDemo.insertData("scores","Bob","score","English","86");
        //Jason
        InsertDemo.insertData("scores","Jason","info","Id","10104");
        InsertDemo.insertData("scores","Jason","info","grade","3");
        InsertDemo.insertData("scores","Jason","score","Math","88");
        InsertDemo.insertData("scores","Jason","score","Chinese","93");
        InsertDemo.insertData("scores","Jason","score","English","95");

**/
        //查询数据,查询Carson的语文成绩
        String tableName = "scores";
        String row = "Carson";
        String columnFamily = "score";
        String column = "Chinese";
        
        GetDemo.getData(tableName,row,columnFamily,column);


    }
}

 查询结果如下：

                                                

c.删除数据

  代码如下

import com.carson.HBase.create.CreateDemo;
import com.carson.HBase.deleteData.DeleteDemo;
import com.carson.HBase.getData.GetDemo;
import com.carson.HBase.insertData.InsertDemo;

import java.io.IOException;

public class TestDemo {

    public static void main(String[] args) throws IOException {
/**
        //先创建一个scores的表，列族有info，score
        String[] columnFamily = {"info","score"};
        String tableName = "scores";
        CreateDemo.create(tableName,columnFamily);


        //插入数据
        //插入Carson的信息和成绩
        InsertDemo.insertData("scores","Carson","info","Id","10101");
        InsertDemo.insertData("scores","Carson","info","grade","4");
        InsertDemo.insertData("scores","Carson","score","Math","97");
        InsertDemo.insertData("scores","Carson","score","Chinese","90");
        InsertDemo.insertData("scores","Carson","score","English","80");
        //插入Amy的信息和成绩
        InsertDemo.insertData("scores","Amy","info","Id","10102");
        InsertDemo.insertData("scores","Amy","info","grade","3");
        InsertDemo.insertData("scores","Amy","score","Math","90");
        InsertDemo.insertData("scores","Amy","score","Chinese","70");
        InsertDemo.insertData("scores","Amy","score","English","89");
        //Bob
        InsertDemo.insertData("scores","Bob","info","Id","10103");
        InsertDemo.insertData("scores","Bob","info","grade","5");
        InsertDemo.insertData("scores","Bob","score","Math","95");
        InsertDemo.insertData("scores","Bob","score","Chinese","99");
        InsertDemo.insertData("scores","Bob","score","English","86");
        //Jason
        InsertDemo.insertData("scores","Jason","info","Id","10104");
        InsertDemo.insertData("scores","Jason","info","grade","3");
        InsertDemo.insertData("scores","Jason","score","Math","88");
        InsertDemo.insertData("scores","Jason","score","Chinese","93");
        InsertDemo.insertData("scores","Jason","score","English","95");

**/

        //查询数据,查询Carson的语文成绩
        String tableName = "scores";
        String row = "Carson";
        String columnFamily = "score";
        String column = "Chinese";

        //GetDemo.getData(tableName,row,columnFamily,column);

        //删除数据Carson的info列族中的grade
        DeleteDemo.deleteData(tableName,row,"info","grade");


    }
}

运行之后，在HBase shell中输入scan "scores"，得到如下结果