HBase的编程实践（实验3_熟悉常用的HBase操作）

HBase的编程实践

✿ 准备工作：

■ 先启动hadoop，再启动hbase；（关闭：关闭先关hbase，再关闭hadoop）

□ 启动hadoop：

ssh localhost
cd /usr/local/hadoop
./sbin/start-dfs.sh

□ 启动hbase：(因为hbase 咱将其bin 目录配置了环境变量，相当于全局变量了，在终端命令可以直接使用， 而hadoop 没有配置系统的全局变量，所以需要切换到其安装目录下的sbin 目录)

start-hbase.sh

□ 进入shell界面：

hbase shell

□关闭hbase：

stop-hbase.sh

□关闭hadoop：

cd /usr/local/hadoop
./sbin/stop-dfs.sh

 可能遇到bug：org.apache.hadoop.hbase.PleaseHoldException:Maste is initializing

  logs中报错：master.HMaster: Master failed to complete initialization after 900000ms. Please consider submitting a bug report including a thread dump of this process.

 master.SplitLogManger:error while splitting logs in [hdfs:// localhost:9000/hbase/WALS...]

屋漏偏逢连夜雨：又卡住。。。。。

 解决：ctr+c，关闭hbase、关闭hadoop，然后，关掉shell，重启，然后重新登录。。。（ssh localhost 又发现。。。，直觉，这个问题无伤大雅，跳过它）

Failed to connect to https://changelogs.ubuntu.com/meta-relese-lts.Check your Internet connection or proxy settings.

 诡异的事。。。（前一秒成功创建了一张表，下一秒卡死）

 日志显示：【诡异的地方是在，我创建的表格名为user 就卡住，创建叫其他名字的表格就没事】

警告：WARN[ProcExecTimeout] assignment.AssignmentManger：STUCK Region-In-Transition rit=OPENING, location=null，table=user，region=d7e...

然后又：ERROR:master.HMasterCommandLine:Master exiting。。。

 至此越搞越多bug，我选择重新安装（因为重新安装对于解决问题的是一个优解，为什么不重新安装呢，办法没有高低贵贱，高效即最好。）

也许一开始的原因在于删除表的命令输入先后顺序有问题，我是先输入：truncate 'user' （‘user’ 是表名） 然后输入 drop 'user' #停用表之后才能删除

（好像输入 drop命令前已经停表了哈哈哈）问题不大，重新装一下即可

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

一、Hbase中使用Shell命令：

① HBase中创建表：（create 命令：第一个变量是表名，然后是列族名）

语法：create '表名称','列族名称1','列族名称2','列族名称N'

create 'student','Sname','Ssex','Sage','Sdept','course'

通过命令 describe 'student'  进行查看表的结构：（desc ‘表名’，查看表的结构）

接下来是hbase 常规操作（增删改查）

✿ 增加数据

② put：（put 命令：第一个变量是表名，第二个变量是行键，第三个变量开始就是添加列族情况啦（列限定符可选）

 注意 put 命令：一次只能为一个表的一行数据的一个列，也就是一次只能给一个单元格添加一个数据，

所以直接用shell命令插入数据效率很低，在实际应用中，一般都是利用编程操作数据。

语法：put '表名称','行名称','列名称:','值'

例子：student表添加了学号为95001，名字为LiYing的一行数据，其行键为95001。

put 'student', '95001','Sname','LiYing'

例子：为95001行下的course列族的math列添加了一个数据：

put 'student','95001','course:math','80'

在表格中的样子（大概如此，变量名不一定对得上哦，我只是为了展示表格的形式）：

 ✿ 删除数据

③ delete命令：

□ put 的反向操作：

□ 删除 一行中的所有数据：

□ 删除 表：

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

□ put 的反向操作：

delete 'student','95001','Sname:firstName'

 □ 删除 一行中的所有数据：

deleteall 'student','95001'

 □ 删除表 ：

disable 'student'      #让表不可用
drop 'student'         #删除表

✿ 查看数据：

□ get： 查看的是一行中的数据

□ scan： 查看的是表中的全部数据

get 'student','95001'

scan 'student'

 还可以查询部分细节的数据等等细节的数据，例如：查询 某个列族的数据：

 ✿  查询表历史数据：

④ 查询表的历史版本，需要两步。
1、在创建表的时候，指定保存的版本数（假设指定为5）

create 'teacher',{NAME=>'username',VERSIONS=>5}

2、插入数据然后更新数据，使其产生历史版本数据，注意：这里插入数据和更新数据都是用put命令

put 'teacher','91001','username','Mary'
put 'teacher','91001','username','Mary1'
put 'teacher','91001','username','Mary2'
put 'teacher','91001','username','Mary3'
put 'teacher','91001','username','Mary4'  
put 'teacher','91001','username','Mary5'

3、查询时，指定查询的历史版本数。默认会查询出最新的数据

get 'teacher','91001',{COLUMN=>'username',VERSIONS=>3}

 ✿ 退出HBase数据库操作

⑤ 命令： exit

注意：这里退出HBase数据库是退出对数据库表的操作，而不是停止启动HBase数据库后台运行。

 二、Hbase编程实践：

✿ 准备工作：导入jar包：

导包步骤：File -》 Project Structure -》Libraries -》+ -》选择需要导入的包，然后记得导入完成后，点击一下 Apply，再点 Ok

（1） 进入到“/usr/local/hbase/lib”目录，选中该目录下的所有jar文件（注意，不要选中client-facing-thirdparty、ruby、shaded-clients和zkcli这四个目录）

（2）  进入到“/usr/local/hbase/lib/client-facing-thirdparty”目录, 选中该目录下的所有jar文件。

例子：创建表，插入数据，查看表中数据

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.util.Bytes;
 
import java.io.IOException;
public class ExampleForHBase {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;
    public static void main(String[] args)throws IOException{
        init();　　　　//主要操作就是为了连接到数据库hbase
        createTable("student",new String[]{"score"});　　　　//创建表，shell命令：create '表名'，'列族名1'，'列族名2'，'列族名3' ...
        insertData("student","zhangsan","score","English","69"); //shell命令： put 'student'，'张三'，'score：English'，'69'
        insertData("student","zhangsan","score","Math","86");
        insertData("student","zhangsan","score","Computer","77");
        getData("student", "zhangsan", "score","English");
        close();
    }
 
    public static void init(){
        configuration  = HBaseConfiguration.create();
        configuration.set("hbase.rootdir","hdfs://localhost:9000/hbase");
        try{
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        }catch (IOException e){
            e.printStackTrace();
        }
    }
 
    public static void close(){
        try{
            if(admin != null){
                admin.close();
            }
            if(null != connection){
                connection.close();
            }
        }catch (IOException e){
            e.printStackTrace();
        }
    }
 
    public static void createTable(String myTableName,String[] colFamily) throws IOException {
        TableName tableName = TableName.valueOf(myTableName);
        if(admin.tableExists(tableName)){
            System.out.println("talbe is exists!");
        }else {
            TableDescriptorBuilder tableDescriptor = TableDescriptorBuilder.newBuilder(tableName);
            for(String str:colFamily){
                ColumnFamilyDescriptor family = 
ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(str)).build();
                tableDescriptor.setColumnFamily(family);
            }
            admin.createTable(tableDescriptor.build());
        } 
    }
 
    public static void insertData(String tableName,String rowKey,String colFamily,String col,String val) throws IOException { 
        Table table = connection.getTable(TableName.valueOf(tableName));
        Put put = new Put(rowKey.getBytes());
        put.addColumn(colFamily.getBytes(),col.getBytes(), val.getBytes());
        table.put(put);
        table.close(); 
    }
 
    public static void getData(String tableName,String rowKey,String colFamily, String col)throws  IOException{ 
        Table table = connection.getTable(TableName.valueOf(tableName));
        Get get = new Get(rowKey.getBytes());
        get.addColumn(colFamily.getBytes(),col.getBytes());
        Result result = table.get(get);
        System.out.println(new String(result.getValue(colFamily.getBytes(),col==null?null:col.getBytes())));
        table.close(); 
    }
}

运行程序后，到终端输入：scan ‘student’ 查看一下

三、实验：熟悉常用的HBase 操作：

（一）编程实现以下指定功能，并用 Hadoop 提供的 HBase Shell 命令完成相同任务：

1. 列出 HBase 所有的表的相关信息，例如表名；
2. 在终端打印出指定的表的所有记录数据；
3. 向已经创建好的表添加和删除指定的列族或列；
4. 清空指定的表的所有记录数据；
5. 统计表的行数。

1.列出 HBase 所有的表的相关信息，例如表名：

■ HBase Shell：List

■ Java Api:

/**
* 同样是正常的建立 数据库连接，执行操作，然后最后关闭连接
*  重点是：HTableDescriptor hTableDescriptors[] = admin.listTables(); 获取到 表格列表，然后遍历
*/
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import java.io.IOException;
public class Test_1 {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;
    /**
     * 建立连接
     */
    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 关闭连接
     */
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    /**
     * 
     * 查看已有表,通过方法listTables()
     * 
     * @throws IOException
     * 
     */
    public static void listTables() throws IOException {
        init();
        HTableDescriptor hTableDescriptors[] = admin.listTables();
        for (HTableDescriptor hTableDescriptor : hTableDescriptors) {
            System.out.println(hTableDescriptor.getNameAsString());
        }
        close();
    }
    
    public static void main(String[] args) {
        Test_1 t = new Test_1();
        try {
            System.out.println("以下为Hbase 数据库中所存的表信息");
            t.listTables();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2.在终端打印出指定的表的所有记录数据；

■ HBase Shell：scan 'student'

■ Java Api:

/**
* 同样是正常的建立 数据库连接，执行操作，然后最后关闭连接
* 重点是： 
* Table table = connection.getTable(TableName.valueOf(tableName));获取到表格对象
* Scan scan = new Scan(); ResultScanner scanner = table.getScanner(scan); 然后通过Scanner对象，获取到ResultScanner扫描结果对象，遍历输出
*/
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import java.io.IOException;
import java.util.Scanner;
public class Test_2 {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;
    // 建立连接
    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    // 关闭连接
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();

        }
    }
    /**
     * 
     * 根据表名查找表信息
     * 
     */
    public static void getData(String tableName) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Scan scan = new Scan();
        ResultScanner scanner = table.getScanner(scan);
        for (Result result : scanner)
        {
            showCell((result));
        }
        close();
    }

    /**
     * 
     * 格式化输出
     * 
     * @param result
     * 
     */
    public static void showCell(Result result) {
        Cell[] cells = result.rawCells();
        for (Cell cell : cells) {
            System.out.println("RowName(行键):" + new String(CellUtil.cloneRow(cell)) + " ");
            System.out.println("Timetamp(时间戳):" + cell.getTimestamp() + " ");
            System.out.println("column Family（列簇）:" + new String(CellUtil.cloneFamily(cell)) + " ");
            System.out.println("column Name（列名）:" + new String(CellUtil.cloneQualifier(cell)) + " ");
            System.out.println("value:（值）" + new String(CellUtil.cloneValue(cell)) + " ");
            System.out.println();
        }
    }
    public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
        Test_2 t = new Test_2();
        System.out.println("请输入要查看的表名");
        Scanner scan = new Scanner(System.in);
        String tableName = scan.nextLine();
        System.out.println("信息如下：");
        t.getData(tableName);
    }
}

3,向已经创建好的表添加和删除指定的列族或列:

■ HBase Shell：

put 'student','95003','Sname','wangjinxuan' 　　　　(添加列)

put 'student','95003','Sname:nickName','wang'　　　　(添加列族)

put 'student','95003','Sname:firstName','jinxuan'    （添加列族）

put的反向操作的delete：

delete 'student' ,’95003’,’Sname’

delete 'student' ,’95003’,’Sname:nickName’

deleteall 'student' ,’95003’   　(删除整个行记录)

■ Java Api:

/**
 * hbase只关注rowkey，column Family（列族），并没有说在创建表的时候指定cq（列限定修饰符）有多少，这也是hbase列式存储的特点，
 *     所以在hbase API中是没有提供delete 一个列下的所有数据的
 * 
 *     同样是正常的建立 数据库连接，执行操作，然后最后关闭连接
 * 1，Table table = connection.getTable(TableName.valueOf(tableName)); 先获取到表
 * 2，插入：（① 创建Put对象，② 然后通过方法 addColumn将列、列限定符、值 放到put对象，③ 最后将put对象put到表格）
 *     Put put = new Put(rowKey.getBytes());
 *  put.addColumn(colFamily.getBytes(), col.getBytes(), val.getBytes());
 *  table.put(put);        
 * 3，删除：
 * Table table = connection.getTable(TableName.valueOf(tableName)); 同样首先获取到表
 * Delete delete = new Delete(rowKey.getBytes());    //通过传入行键，new一个删除对象    
 * //删除对象添加要被删除的列或列族                        
 * ① 删除指定列族的所有数据（此情况是列族下无列限定符时的情况）：delete.addFamily(colFamily.getBytes());        
 * ② 删除指定列的数据（此列主要说的是列限定修饰符）：delete.addColumn(colFamily.getBytes(), col.getBytes());
 * table.delete(delete); //最后就是表格delete掉 delete对象
 */

import java.io.IOException;
import java.util.Scanner;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Delete;
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.client.Table;

public class Test_3 {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    // 建立连接
    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 关闭连接
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 向某一行的某一列插入数据
     * 
     * @param tableName 表名
     * @param rowKey    行键
     * @param colFamily 列族名
     * @param col       列名（如果其列族下没有子列，此参数可为空）
     * @param val       值
     * @throws IOException
     */
    public static void insertRow(String tableName, String rowKey, String colFamily, String col, String val)throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Put put = new Put(rowKey.getBytes());
        put.addColumn(colFamily.getBytes(), col.getBytes(), val.getBytes());
        table.put(put);
        table.close();
        close();
    }

    /**
     * 根据表名查找表信息
     */
    public static void getData(String tableName) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Scan scan = new Scan();
        ResultScanner scanner = table.getScanner(scan);
        for (Result result : scanner) {
            showCell((result));
        }
        close();
    }
    /**
     * 
      * 格式化输出
     * 
     * @param result
     * 
     */
    public static void showCell(Result result) {
        Cell[] cells = result.rawCells();
        for (Cell cell : cells) {
            System.out.println("RowName(行键):" + new String(CellUtil.cloneRow(cell)) + " ");
            System.out.println("Timetamp(时间戳):" + cell.getTimestamp() + " ");
            System.out.println("column Family（列簇）:" + new String(CellUtil.cloneFamily(cell)) + " ");
            System.out.println("column Name（列名）:" + new String(CellUtil.cloneQualifier(cell)) + " ");
            System.out.println("value:（值）" + new String(CellUtil.cloneValue(cell)) + " ");
            System.out.println();
        }
    }
    /**
     * 
     * 删除数据
     * 
     * @param tableName 表名
     * 
     * @param rowKey    行键
     * 
     * @param colFamily 列族名
     * 
     * @param col       列名
     * 
     * @throws IOException
     * 
     */
    public static void deleteRow(String tableName, String rowKey, String colFamily, String col) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Delete delete = new Delete(rowKey.getBytes());
        if(col == null) {
            //删除指定列族的所有数据（此情况是列族下无列限定符时的情况）
            delete.addFamily(colFamily.getBytes());
            table.delete(delete);
            table.close();
        }else {
            //删除指定列的数据（此列主要说的是列限定修饰符）
            delete.addColumn(colFamily.getBytes(), col.getBytes());
            table.delete(delete);
            table.close();
        }
        close();
    }

    public static void main(String[] args) {
        Test_3 t = new Test_3();
        boolean flag = true;
        while (flag){
            System.out.println("------------向已经创建好的表中添加和删除指定的列簇或列--------------------");
            System.out.println("              请输入您要进行的操作   1- 添加          2-删除                       ");
            Scanner scan = new Scanner(System.in);
            String choose1 = scan.nextLine();
            switch (choose1) {
            case "1":
                try {
                    //put 'student','95003','Sname','wangjinxuan' 　　　　(添加列)
                    //put 'student','95003','Sname:nickName','wang'　　　　(添加列族)
                    //put 'student','95003','Sname:firstName','jinxuan'  （添加列族）
//                    t.insertRow(tableName, rowKey, colFamily, col, val);
                    t.insertRow("student", "95003", "Sname",null, "wangjingxuan");
                    t.insertRow("student", "95003", "Sname", "nickName", "wang");
                    t.insertRow("student", "95003", "Sname", "firstName", "jingxuan");
                    System.out.println("插入成功：");
                    t.getData(tableName);
                } catch (IOException e) {
                    e.getMessage();
                }
                break;
            case "2":
                try {
                    System.out.println("----------------------删除前，表的原本信息如下---------------------");
                    t.getData(tableName);
                    //delete 'student' ,’95003’,’Sname’
                    //delete 'student' ,’95003’,’Sname:nickName’
//                    t.deleteRow(tableName, rowKey, colFamily, col);    
                    t.deleteRow("student", "95003", "Sname", "firstName");    
                    System.out.println("-----------------------删除成功-----------------------------\n");
                    System.out.println("---------------------删除后，表的信息如下---------------------");
                    t.getData(tableName);
                } catch (IOException e) {
                    e.getMessage();
                }
                break;
            }
            System.out.println(" 你要继续操作吗？ 是-true 否-false ");
            flag = scan.nextBoolean();
        }
        System.out.println("   程序已退出！    ");
    }
}

4，清空指定的表的所有记录数据：

■ HBase Shell：truncate 'student'

■ Java Api:

import java.io.IOException;
import java.util.Scanner;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.HBaseAdmin;
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.client.Table;
import org.apache.hadoop.hbase.util.Bytes;
public class Test_4 {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;
    // 建立连接
    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    // 关闭连接
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 
     * 清空制定的表的所有记录数据
     * 
     * @param args
     * 
     * @throws IOException
     * 
     */
    public static void clearRows(String tableName) throws IOException {
        init();
        HBaseAdmin admin1 = new HBaseAdmin(configuration);
        // 读取了之前表的表名 列簇等信息，然后再进行删除操作。
        HTableDescriptor tDescriptor = admin1.getTableDescriptor(Bytes.toBytes(tableName));
        // 总思想是先将原表结构保留下来，然后进行删除，再重新依据保存的信息重新创建表。
        TableName tablename = TableName.valueOf(tableName);
        // 删除表
        admin.disableTable(tablename);
        admin.deleteTable(tablename);
        // 重新建表
        admin.createTable(tDescriptor);
        close();
    }
    /**
     * 
     * 根据表名查找表信息
     * 
     */
    public static void getData(String tableName) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Scan scan = new Scan();
        ResultScanner scanner = table.getScanner(scan);
        for (Result result : scanner){
            showCell((result));
        }
        close();
    }

    /**
     * 
     * 格式化输出
     * 
     * @param result
     * 
     */
    public static void showCell(Result result) {
        Cell[] cells = result.rawCells();
        for (Cell cell : cells) {
            System.out.println("RowName(行键):" + new String(CellUtil.cloneRow(cell)) + " ");
            System.out.println("Timetamp(时间戳):" + cell.getTimestamp() + " ");
            System.out.println("column Family（列簇）:" + new String(CellUtil.cloneFamily(cell)) + " ");
            System.out.println("column Name（列名）:" + new String(CellUtil.cloneQualifier(cell)) + " ");
            System.out.println("value:（值）" + new String(CellUtil.cloneValue(cell)) + " ");
            System.out.println();
        }
    }

    public static void main(String[] args) {
        Test_4 test_4 = new Test_4();
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入要清空的表名");
        String tableName = scan.nextLine();
        try {
            System.out.println("表原来的信息：");
            test_4.getData(tableName);
            test_4.clearRows(tableName);
            System.out.println("表已清空：");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

5,统计表的行数:

■ HBase Shell：count 'student'

■ Java Api:

import java.io.IOException;
import java.util.Scanner;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
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.client.Table;
public class Test_5 {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;
    //建立连接
    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    // 关闭连接
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void countRows(String tableName) throws IOException{
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Scan scan = new Scan();
        ResultScanner scanner = table.getScanner(scan);
        int num = 0;
        for (Result result = scanner.next(); result != null; result = scanner.next()){
            num++;
        }
        System.out.println("行数：" + num);
        scanner.close();
        close();
    }
    public static void main(String[] args) throws IOException {
        Test_5 test_5 = new Test_5();
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入要统计行数的表名");
        String tableName = scan.nextLine();
        test_5.countRows(tableName);
    }
}

（二）现有以下关系型数据库中的表和数据，要求将其转换为适合于HBase存储的表并插入数据：

学生表（Student）、课程表（Course）、选课表（SC）：同时，请编程完成以下指定功能：

create 'Student','S_No','S_Name','S_Sex','S_Age'
put 'Student','s001','S_No','2015001'
put 'Student','s001','S_Name','Zhangsan'
put 'Student','s001','S_Sex','male'
put 'Student','s001','S_Age','23'
put 'Student','s002','S_No','2015002'
put 'Student','s002','S_Name','Mary'
put 'Student','s002','S_Sex','female'
put 'Student','s002','S_Age','22'
put 'Student','s003','S_No','2015003'
put 'Student','s003','S_Name','Lisi'
put 'Student','s003','S_Sex','male'
put 'Student','s003','S_Age','24'
—————————————————————————————————————————————————————————————————————————————
create 'Course','C_No','C_Name','C_Credit'
put 'Course','c001','C_No','123001'
put 'Course','c001','C_Name','Math'
put 'Course','c001','C_Credit','2.0'
put 'Course','c002','C_No','123002'
put 'Course','c002','C_Name','Computer'
put 'Course','c002','C_Credit','5.0'
put 'Course','c003','C_No','123003'
put 'Course','c003','C_Name','English'
put 'Course','c003','C_Credit','3.0'
————————————————————————————————————————————————————————————————————————————————
put 'SC','sc001','SC_Sno','2015001'
put 'SC','sc001','SC_Cno','123001'
put 'SC','sc001','SC_Score','86'
put 'SC','sc002','SC_Sno','2015001'
put 'SC','sc002','SC_Cno','123003'
put 'SC','sc002','SC_Score','69'
put 'SC','sc003','SC_Sno','2015002'
put 'SC','sc003','SC_Cno','123002'
put 'SC','sc003','SC_Score','77'
put 'SC','sc004','SC_Sno','2015002'
put 'SC','sc004','SC_Cno','123003'
put 'SC','sc004','SC_Score','99'
put 'SC','sc005','SC_Sno','2015003'
put 'SC','sc005','SC_Cno','123001'
put 'SC','sc005','SC_Score','98'
put 'SC','sc006','SC_Sno','2015003'
put 'SC','sc006','SC_Cno','123002'
put 'SC','sc006','SC_Score','95'

同时，请编程完成以下指定功能：

① createTable(String tableName, String[] fields)： 创建表，参数tableName为表的名称，字符串数组fields为存储记录各个域名称的数组。

（域名称即列族名称啦）要求当HBase已经存在名为tableName的表的时候，先删除原有的表，然后再创建新的表。

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.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;

import java.io.IOException;

public class CreateTable {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    public static void createTable(String tableName, String[] fields) throws IOException {
        init();
        TableName tablename = TableName.valueOf(tableName);
        if (admin.tableExists(tablename)) {
            System.out.println("table is exists!");
            admin.disableTable(tablename);
            admin.deleteTable(tablename);
        }
        HTableDescriptor hTableDescriptor = new HTableDescriptor(tablename);
        for (String str : fields) {
            HColumnDescriptor hColumnDescriptor = new HColumnDescriptor(str);
            hTableDescriptor.addFamily(hColumnDescriptor);
        }
        admin.createTable(hTableDescriptor);
        close();
    }

    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        String[] fields = {"Score"};
        try {
            createTable("person", fields);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

② addRecord(String tableName, String row, String[] fields, String[] values)： 向表tableName、行row（用S_Name表示）和字符串数组files指定的单元格中添加对应的数据values。其中fields中每个元素如果对应的列族下还有相应的列限定符的话，用"columnFamily:column"表示。例如，同时向"Math"、“Computer Science”、"English"三列添加成绩时，字符串数组fields为{“Score:Math”, “Score: Computer Science”, “Score:English”}，数组values存储这三门课的成绩。

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;

import java.io.IOException;

public class AddRecord {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    public static void addRecord(String tableName, String row, String[] fields, String[] values) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        for (int i = 0; i != fields.length; i++) {
            Put put = new Put(row.getBytes());
            String[] cols = fields[i].split(":");
            put.addColumn(cols[0].getBytes(), cols[1].getBytes(), values[i].getBytes());
            table.put(put);
        }
        table.close();
        close();
    }

    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        String[] fields = {"Score:Math", "Score:Computer Science", "Score:English"};
        String[] values = {"99", "80", "100"};
        try {
            addRecord("person", "Score", fields, values);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

③ scanColumn(String tableName, String column)： 浏览表tableName某一列的数据，如果某一行记录中该列数据不存在，则返回null。要求当参数column为某一列族名称时，如果底下有若干个列限定符，则要列出每个列限定符代表的列的数据；当参数column为某一列具体名称（例如"Score:Math"）时，只需要列出该列的数据。

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.util.Bytes;

import java.io.IOException;

public class ScanColumn {
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    public static void scanColumn(String tableName, String column) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Scan scan = new Scan();
        scan.addFamily(Bytes.toBytes(column));
        ResultScanner scanner = table.getScanner(scan);
        for (Result result = scanner.next(); result != null; result = scanner.next()) {
            showCell(result);
        }
        table.close();
        close();
    }

    public static void showCell(Result result) {
        Cell[] cells = result.rawCells();
        for (Cell cell : cells) {
            System.out.println("RowName:" + new String(CellUtil.cloneRow(cell)) + " ");
            System.out.println("Timetamp:" + cell.getTimestamp() + " ");
            System.out.println("column Family:" + new String(CellUtil.cloneFamily(cell)) + " ");
            System.out.println("row Name:" + new String(CellUtil.cloneQualifier(cell)) + " ");
            System.out.println("value:" + new String(CellUtil.cloneValue(cell)) + " ");
        }
    }

    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 关闭连接
    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        try {
            scanColumn("person", "Score");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

④ modifyData(String tableName, String row, String column)： 修改表tableName，行row（可以用学生姓名S_Name表示），列column指定的单元格的数据。

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;

import java.io.IOException;

public class ModifyData {

    public static long ts;
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    public static void modifyData(String tableName, String row, String column, String val) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Put put = new Put(row.getBytes());
        Scan scan = new Scan();
        ResultScanner resultScanner = table.getScanner(scan);
        for (Result r : resultScanner) {
            for (Cell cell : r.getColumnCells(row.getBytes(), column.getBytes())) {
                ts = cell.getTimestamp();
            }
        }
        put.addColumn(row.getBytes(), column.getBytes(), ts, val.getBytes());
        table.put(put);
        table.close();
        close();
    }

    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        try {
            modifyData("person", "Score", "Math", "100");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

⑤ deleteRow(String tableName, String row)： 删除表tableName中row指定的行的记录。

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;

import java.io.IOException;

public class ModifyData {

    public static long ts;
    public static Configuration configuration;
    public static Connection connection;
    public static Admin admin;

    public static void modifyData(String tableName, String row, String column, String val) throws IOException {
        init();
        Table table = connection.getTable(TableName.valueOf(tableName));
        Put put = new Put(row.getBytes());
        Scan scan = new Scan();
        ResultScanner resultScanner = table.getScanner(scan);
        for (Result r : resultScanner) {
            for (Cell cell : r.getColumnCells(row.getBytes(), column.getBytes())) {
                ts = cell.getTimestamp();
            }
        }
        put.addColumn(row.getBytes(), column.getBytes(), ts, val.getBytes());
        table.put(put);
        table.close();
        close();
    }

    public static void init() {
        configuration = HBaseConfiguration.create();
        configuration.set("hbase.rootdir", "hdfs://localhost:9000/hbase");
        try {
            connection = ConnectionFactory.createConnection(configuration);
            admin = connection.getAdmin();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void close() {
        try {
            if (admin != null) {
                admin.close();
            }
            if (null != connection) {
                connection.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        try {
            modifyData("person", "Score", "Math", "100");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

 参考：

《​​HBase2.2.2安装和编程实践指南_厦大数据库实验室博客 (xmu.edu.cn)​​》

《实验3 熟悉常用的 HBase 操作》​​​​

《实验3_熟悉常用的HBase操作》​

​

作者：一乐乐