JDBC——java连接mysql、hive、hbase教程

一、准备工作

1.1、创建Maven工程

工程ID

Maven工作目录

保存路径

进入工程，选择Enable Auto-Import，允许自动导包

1.2、修改pom文件

1.修改properties里的编译版本，此处用的是jdk1.8，所以改为1.8

1.3、修改Project Structure

Language level改成版本8

1.4、修改Settings

编译版本改成8

1.5、资源文件夹

1.创建文件夹
src->main下创建resources文件夹

2.设置为资源文件夹
右击resources文件夹，Mark Directory as->Resources Root

---

二、Java连接mysql

2.1、添加依赖

在<dependencies></dependencies>中添加依赖

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.38</version>
</dependency>

pom.xml文件内容如下

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>cn.template.jdbc</groupId>
  <artifactId>java2mhh</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>java2mhh</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.38</version>
    </dependency>
  </dependencies>

  <build>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.7.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

---

2.2、JDBC配置文件

resources文件夹下新建文件datasource.properties

文件内容如下

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://192.168.247.130:3306/mysqltest?useUnicode=true&characterEncoding=utf8&useSSL=true
username=root
password=javakb10

---

2.3、代码编写

（1）BaseConfig类，初始化连接

package cn.template.jdbc;

import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class BaseConfig {
    
    
    //定义内部类Config，使用其对象作为BaseConfig的成员变量，加载驱动等信息
    private class Config {
    
    
        String driver;
        String url;
        String username;
        String password;
    }

    private Config config;

    //正则匹配，检查url格式是否有效
    private boolean valid(String url) {
    
    
        Pattern p = Pattern.compile("jdbc:\\w+://((\\d{1,3}\\.){3}\\d{1,3}|\\w+):\\d{1,5}/\\w+");
        Matcher m = p.matcher(url);
        return m.matches();
    }

    //用代码块调用init方法,加载数据库配置信息并加载驱动driver
    {
    
    
        //静态代码块  异常无法抛出
        try {
    
    
            init();
            //驱动装载
            Class.forName(config.driver);
        } catch (Exception e) {
    
    
            System.err.println(e.getMessage());
        }
    }

    //init方法将配置信息加载到BaseConfig的成员变量config上
    private void init() throws Exception {
    
    
        //用线程读取读取资源文件datasource.properties的路径
        String path = Thread.currentThread().getContextClassLoader()
                .getResource("datasource.properties").getPath();
        //使用Properties包装类解析properties文件
        Properties pro = new Properties();
        pro.load(new FileReader(path));
        String url = pro.getProperty("url");
        if (url == null || !valid(url)) {
    
    
            throw new Exception("url is null or invalid!");
        }
        config = new Config();
        config.url = url;
        config.driver = pro.getProperty("driver", "com.mysql.jdbc.driver");
        config.username = pro.getProperty("username", "root");
        config.password = pro.getProperty("password", "root");
        pro.clear();

    }

    //获得数据库连接Connection
    protected Connection getCon() throws SQLException {
    
    
        return DriverManager.getConnection(config.url, config.username, config.password);
    }

    //关闭线程方法
    protected void close(AutoCloseable... acs) {
    
    
        if (acs != null) {
    
    
            for (AutoCloseable ac : acs) {
    
    
                try {
    
    
                    ac.close();
                } catch (Exception e) {
    
    
                    e.printStackTrace();
                }
            }
        }
    }
}

（2）Result类，获取sql语句结果

package cn.template.jdbc;

public class Result<T> {
    
    
    private T data;
    private boolean isErr;

    public Result( boolean isErr,T data) {
    
    
        this.data = data;
        this.isErr = isErr;
    }

    public T getData() {
    
    
        return data;
    }

    public boolean isErr() {
    
    
        return isErr;
    }

    public static <T>Result Succeed(T data){
    
    
        return new Result(false,data);
    }

    public static Result Fail(){
    
    
        return new Result(true,null);
    }
}

（3）BaseDao类，编译sql语句

package cn.template.jdbc;

import java.io.BufferedReader;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class BaseDao extends BaseConfig {
    
    

    //预编译执行器PreparedStatement（防止sql注入）
    private PreparedStatement getPst(Connection con, String sql, Object...params) throws SQLException {
    
    
        PreparedStatement pst=con.prepareStatement(sql);
        if(params.length>0){
    
    
            for (int i = 0; i < params.length; i++) {
    
    
                pst.setObject(i+1,params[i]);
            }
        }
        return  pst;
    }

    //非查询语句调用方法
    public Result exeNonQuery(String sql,Object...params){
    
    
        Connection con=null;
        PreparedStatement pst=null;
        try {
    
    
            con=getCon();
            pst=getPst(con,sql,params);
            return Result.Succeed(pst.executeUpdate());
        } catch (SQLException e) {
    
    
            e.printStackTrace();
            return Result.Fail();
        }finally {
    
    
            close(pst,con);
        }
    }

    //查询语句调用方法
    public Result exeQuery(String sql,Object...params){
    
    
        Connection con=null;
        PreparedStatement pst=null;
        ResultSet rst=null;
        List<List<String>> data=new ArrayList<>();
        try {
    
    
            con=getCon();
            pst=getPst(con,sql,params);
            rst=pst.executeQuery();
            final int COUNT=rst.getMetaData().getColumnCount();
            while (rst.next()){
    
    
                List<String> row=new ArrayList<>(COUNT);
                for (int i = 1; i <= COUNT; i++) {
    
    
                    row.add(rst.getObject(i).toString());
                }
                data.add(row);
            }
            return Result.Succeed(data);
        } catch (SQLException e) {
    
    
            e.printStackTrace();
            return Result.Fail();
        }finally {
    
    
            close(rst,pst,con);
        }
    }

    //readSql方法，用于读取本地文件中的sql语句
    public String readSql(String...paths) throws Exception {
    
    
        String path=paths.length==0?"sql/sql.sql":paths[0];
        StringBuilder builder=new StringBuilder();
        BufferedReader read=new BufferedReader(new FileReader(path));
        String line=null;
        while (null!=(line=read.readLine())){
    
    
            builder.append(line.trim()+" ");
        }
        return builder.toString();
    }
    
}

2.4、测试

①测试查询语句

public class Test {
    
    
    public static void main(String[] args) throws Exception{
    
    

        BaseDao dao=new BaseDao();
        Result<List<List<String>>> result = dao.exeQuery("select * from student");

        List<List<String>>  table=result.getData();
        table.forEach(tab->{
    
    
            tab.forEach(row->{
    
    
                System.out.print(row+"\t");
            });
            System.out.println();
        });

    }
}

查询结果

②用文件测试非查询语句

原course表

本地sql文件内容如下

执行测试代码

public class Test {
    
    
    public static void main(String[] args) throws Exception{
    
    
        BaseDao dao=new BaseDao();
        Result result = dao.exeNonQuery(dao.readSql());
        System.out.println(result.toString());
    }
}

结果

---

三、Java连接hive

3.1、添加依赖

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>cn.template.jdbc</groupId>
  <artifactId>java2mhh</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>java2mhh</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <hadoop.version>2.6.0</hadoop.version>
    <hive.version>1.1.0</hive.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.hive</groupId>
      <artifactId>hive-jdbc</artifactId>
      <version>${
    
    hive.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-auth</artifactId>
      <version>${
    
    hadoop.version}</version>
      <exclusions>
        <exclusion>
          <artifactId>jdk.tools</artifactId>
          <groupId>jdk.tools</groupId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-common</artifactId>
      <version>${
    
    hadoop.version}</version>
      <exclusions>
        <exclusion>
          <artifactId>jdk.tools</artifactId>
          <groupId>jdk.tools</groupId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-hdfs</artifactId>
      <version>${
    
    hadoop.version}</version>
      <exclusions>
        <exclusion>
          <artifactId>jdk.tools</artifactId>
          <groupId>jdk.tools</groupId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-client</artifactId>
      <version>${
    
    hadoop.version}</version>
      <exclusions>
        <exclusion>
          <artifactId>jdk.tools</artifactId>
          <groupId>jdk.tools</groupId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-mapreduce-client-core</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>
  </dependencies>

  <build>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.7.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

3.2、配置文件

datasource文件内容如下，不需要password，默认使用default数据库

driver=org.apache.hive.jdbc.HiveDriver
url=jdbc:hive2://192.168.247.130:10000/default
username=root

resources文件夹下添加文件log4j.properties，内容如下

log4j.rootLogger=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/hadoop.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

3.3、代码编写

与Java连接mysql区别不大，只需要修改BaseConfig类的init()方法

修改config.password，将密码的默认值设置为空，因为用不到

    private void init() throws Exception {
    
    
        //用线程读取读取资源文件datasource.properties的路径
        String path = Thread.currentThread().getContextClassLoader()
                .getResource("datasource.properties").getPath();
        //使用Properties包装类解析properties文件
        Properties pro = new Properties();
        pro.load(new FileReader(path));
        String url = pro.getProperty("url");
        if (url == null || !valid(url)) {
    
    
            throw new Exception("url is null or invalid!");
        }
        config = new Config();
        config.url = url;
        config.driver = pro.getProperty("driver", "com.mysql.jdbc.driver");
        config.username = pro.getProperty("username", "root");
        config.password = pro.getProperty("password", "");
        pro.clear();
    }

---

3.4、测试

hive中default数据库下有如下表

我们使用JDBC查询一下course表

public class Test {
    
    
    public static void main(String[] args) throws Exception{
    
    

        BaseDao dao=new BaseDao();
        Result<List<List<String>>> result = dao.exeQuery("select * from course");

        List<List<String>>  table=result.getData();
        table.forEach(tab->{
    
    
            tab.forEach(row->{
    
    
                System.out.print(row+"\t");
            });
            System.out.println();
        });

    }
}

查询结果如下

---

四、Java连接hbase

4.1、添加依赖

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>cn.template.jdbc</groupId>
  <artifactId>java2mhh</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>java2mhh</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <hadoop.version>2.6.0-cdh5.14.2</hadoop.version>
    <hive.version>1.1.0-cdh5.14.2</hive.version>
    <hbase.version>1.2.0-cdh5.14.2</hbase.version>
  </properties>

  <repositories>
    <repository>
      <id>cloudera</id>
      <url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
    </repository>
  </repositories>

  <dependencies>
    <!--hadoop-->
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-common</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-client</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-hdfs</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>

    <!--日志-->
    <dependency>
      <groupId>commons-logging</groupId>
      <artifactId>commons-logging</artifactId>
      <version>1.2</version>
    </dependency>

    <!--MapReduce-->
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-auth</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-mapreduce-client-core</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
      <version>${
    
    hadoop.version}</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->
    <!--zookeeper-->
    <dependency>
      <groupId>org.apache.zookeeper</groupId>
      <artifactId>zookeeper</artifactId>
      <version>3.4.5</version>
      <type>pom</type>
    </dependency>

    <!--hbase-->
    <dependency>
      <groupId>org.apache.hbase</groupId>
      <artifactId>hbase-client</artifactId>
      <version>${
    
    hbase.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hbase</groupId>
      <artifactId>hbase-common</artifactId>
      <version>${
    
    hbase.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.hbase</groupId>
      <artifactId>hbase-server</artifactId>
      <version>${
    
    hbase.version}</version>
    </dependency>

    <!--log4j-->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.17</version>
    </dependency>

    <!--测试-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <!--<scope>test</scope>-->
    </dependency>
  </dependencies>
</project>

4.2、windows主机映射

修改hosts文件，配置映射

4.3、代码编写

package cn.template.jdbc.hbase;

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 org.junit.Test;

import java.io.IOException;

public class HBaseClientDemo {
    
    
    //创建一个表
    @Test
    public void createTable() throws IOException {
    
    
        //1.获取hbase连接，配置
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum","single");
        conf.set("hbase.zookeeper.property.clientPort","2181");
        //2.创建连接
        Connection conn = ConnectionFactory.createConnection(conf);
        //3.创建admin
        Admin admin=conn.getAdmin();
        //4.创建表的相关信息,表名
        HTableDescriptor student = new HTableDescriptor(TableName.valueOf("HStudent"));
        //5.添加列族信息
        student.addFamily(new HColumnDescriptor("info"));
        student.addFamily(new HColumnDescriptor("score"));
        //6.调用创建表的方法进行建表操作
        admin.createTable(student);
        //7.关闭连接
        conn.close();
    }
    @Test
    public void putData2Table() throws IOException {
    
    
        //1.获取hbase连接，配置
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum","single");
        conf.set("hbase.zookeeper.property.clientPort","2181");
        //2.创建连接
        Connection conn = ConnectionFactory.createConnection(conf);
        //3.获取table
        Table student =conn.getTable(TableName.valueOf("HStudent"));
        //4.表中添加数据rowkey
        Put put=new Put(Bytes.toBytes("1001"));
        //5.添加列 info:name zhangsan
        put.addColumn(Bytes.toBytes("info"),Bytes.toBytes("name"),Bytes.toBytes("Dongue"));
        put.addColumn(Bytes.toBytes("info"),Bytes.toBytes("gender"),Bytes.toBytes("male"));
        put.addColumn(Bytes.toBytes("info"),Bytes.toBytes("age"),Bytes.toBytes("21"));
        //6.插入数据
        student.put(put);
        //7.关闭连接
        conn.close();
    }

    //读取数据
    @Test
    public void getDataFromTable() throws IOException {
    
    
        //1.获取hbase连接，配置
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum","single");
        conf.set("hbase.zookeeper.property.clientPort","2181");
        //2.创建连接
        Connection conn = ConnectionFactory.createConnection(conf);
        //3.获取table
        Table student =conn.getTable(TableName.valueOf("HStudent"));
        //4.读取数据，Get
        Get get = new Get(Bytes.toBytes("1001"));
        //5.获取结果
        Result result = student.get(get);
        //6.遍历
        Cell[] cells = result.rawCells();
        for (Cell cell : cells) {
    
    
            System.out.println("rowkey:"+Bytes.toString(CellUtil.cloneRow(cell)));
            System.out.println("列族:"+Bytes.toString(CellUtil.cloneFamily(cell)));
            System.out.println("列名:"+Bytes.toString(CellUtil.cloneQualifier(cell)));
            System.out.println("value:"+Bytes.toString(CellUtil.cloneValue(cell)));
            System.out.println("-----------------");
        }
        conn.close();
    }

    //删除
    @Test
    public void dropTable() throws IOException {
    
    
        //1.获取hbase连接，配置
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum","single");
        conf.set("hbase.zookeeper.property.clientPort","2181");
        //2.创建连接
        Connection conn = ConnectionFactory.createConnection(conf);
        //3.创建admin
        Admin admin=conn.getAdmin();
        //4.禁用表
        admin.disableTable(TableName.valueOf("HStudent"));
        //5.删除表
        admin.deleteTable(TableName.valueOf("HStudent"));
        conn.close();

    }
}

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