MySQL学习(四)

JDBC

1、数据库驱动

驱动:声卡、显卡、数据库

我们的程序会通过数据库厂商的数据库驱动和数据库打交道!

2、JDBC简介

SUN公司为了简化开发人员的(对数据库的统一)操作,提供了一个(Java操作数据库的)规范,俗称JDBC

这些规范的实现有具体的厂商去做

对于开发人员来说,我们只需要掌握JDBC接口的操作即可!

需要用到java.sql和javax.sql包,这两个包JDK自带;

还需要导入一个数据库驱动包:mysql-connector-java-5.1.47.jar

3、第一个JDBC程序

创建测试数据库

CREATE DATABASE jdbcStudy CHARACTER SET utf8 COLLATE utf8_general_ci;

USE jdbcStudy;

CREATE TABLE users(
    id INT PRIMARY KEY,
    NAME VARCHAR(40),
    PASSWORD VARCHAR(40),
    email VARCHAR(60),
    birthday DATE
);

INSERT INTO users(id,NAME,PASSWORD,email,birthday) 
VALUES(1,'zhansan','123456','zs@sina.com','1980-12-04'),
(2,'lisi','123456','lisi@sina.com','1981-12-04'),
(3,'wangwu','123456','wangwu@sina.com','1979-12-04');

1、创建一个普通项目

2、导入数据库驱动

创建lib,将jar包复制进去,右键,选中ADD as Library,OK

3、编写测试代码

首先给数据库中存入数据

CREATE DATABASE jdbcStudy CHARACTER SET utf8 COLLATE utf8_general_ci;

USE jdbcStudy;

CREATE TABLE users(
    id INT PRIMARY KEY,
    NAME VARCHAR(40),
    PASSWORD VARCHAR(40),
    email VARCHAR(60),
    birthday DATE
);

INSERT INTO users(id,NAME,PASSWORD,email,birthday) 
VALUES(1,'zhansan','123456','zs@sina.com','1980-12-04'),
(2,'lisi','123456','lisi@sina.com','1981-12-04'),
(3,'wangwu','123456','wangwu@sina.com','1979-12-04');
import java.sql.*;

public class JdbcFirstDemo {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        //1、加载驱动
        Class.forName("com.mysql.jdbc.Driver");//固定写法,加载驱动

        //2、用户信息和url
        String url = "jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=true";
        String name = "root";
        String password = "123456";

        //3、连接成功,返回数据库对象
        Connection connection = DriverManager.getConnection(url, name, password);

        //4、获取执行SQL的对象  Statement:是执行SQL的对象
        Statement statement = connection.createStatement();

        //5、执行SQL的对象 去 执行SQL,可能存在结果,查看返回结果
        String sql = "SELECT * FROM users";

        ResultSet resultSet = statement.executeQuery(sql);//返回结果集,结果集中封装了我们全部的查询出来的结果

        while(resultSet.next()){
            System.out.println("id = "+resultSet.getObject("id"));
            System.out.println("name = "+resultSet.getObject("name"));
            System.out.println("password = "+resultSet.getObject("password"));
            System.out.println("email = "+resultSet.getObject("email"));
            System.out.println("birthday = "+resultSet.getObject("birthday"));
            System.out.println("================================================");
        }

        //6、释放连接
        resultSet.close();
        statement.close();
        connection.close();

    }
}

步骤总结:

1、加载驱动

2、连接数据库DiverManger

3、获得之心sql的对象Statement

4、获得返回的结果集

5、释放连接

DiverManger

        Class.forName("com.mysql.jdbc.Driver");//固定写法,加载驱动
        Connection connection = DriverManager.getConnection(url, name, password);
        //conection 代表数据库
        //数据库设置自动提交
        //事务提交 事务回滚
        connection.rollback();
        connection.commit();
        connection.setAutoCommit();

URL

String url = "jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=true";

//mysql  -- 3306
//协议://主机地址:端口号/数据库?参数1&参数2&参数3

//oralce -- 1521
//jdbc:orcale:thin:@localhost:1521:sid

Statement 执行SQL的对象 PrepareStatement执行SQL的对象

String sql = "SELECT * FROM users";//编写SQL

statement.executeQuery();//查询操作返回ResultSet
statement.execute();//执行如何SQL
statement.executeUpdate();//更新、插入、删除、都是用这个,返回一个受影响的行数

ResultSet查询的结果集:封装了所有的查询结果

获得指定的数据类型

resultSet.getObject();//在不知道列类型的情况下使用
//如果知道列的类型就使用指定的类型
resultSet.getString();
resultSet.getInt();
resultSet.getFloat();
resultSet.getDate();
resultSet.getObject();

遍历,指针

resultSet.beforeFirst(); //移动到最前面
resultSet.afterLast();    //移动到最后面
resultSet.next();    //移动到下一个数据
resultSet.previous();    //移动到前一行
resultSet.absolute();    //移动到指定行

释放资源

//耗资源,用完关掉
resultSet.close();
statement.close();
connection.close();

4、statement对象

jdbc中的statement对象用于向数据库发送SQL语句,想完成对数据库的增删改查,只需要通过这个对象先该数据发送增删改查语句即可。

Statement对象的executeUpdate方法,用于向数据发送增、删、改的sql语句,executeUpdate执行完后,将会返回一个整数(即增删改语句导致了数据库几行数据发送了变化)。这个整数就是行数

Statement.executeQuery方法用于向数据库发送查询语句,executeQuery方法返回代表查询结果的Result对象。

CRUD操作-create

使用executeUpdate(String sql)方法完成数据添加操作,示例操作:

Statement st = conn.createStatement(); 
String sql = "insert into user(….) values(…..) "; 
int num = st.executeUpdate(sql); 
if(num>0){
    System.out.println("插入成功!!!"); 
}

CRUD操作-delete

使用executeUpdate(String sql)方法完成数据删除操作,示例操作:

Statement st = conn.createStatement(); 
String sql = "delete from user where id=1"; 
int num = st.executeUpdate(sql); 
if(num>0){    
    System.out.println(“删除成功!!!"); 
}

CRUD操作-update

使用executeUpdate(String sql)方法完成数据修改操作,示例操作:

Statement st = conn.createStatement(); 
String sql = "update user set name='' where name=''"; 
int num = st.executeUpdate(sql); 
if(num>0){
    System.out.println(“修改成功!!!"); 
}

CRUD操作-read

使用executeUpdate(String sql)方法完成数据查询操作,示例操作

Statement st = conn.createStatement(); 
String sql = "select * from user where id=1"; 
ResultSet rs = st.executeQuery(sql); 
while(rs.next()){
    //根据获取列的数据类型,分别调用rs的相应方法映射到java对象中 
}

代码实现

在src下建立资源文件db.properties

driver=com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=true
username = root
password = 123456

1、提取工具类

package com.star.lesson02.utils;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils {
    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;

    static {
        try {
            InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties properties = new Properties();
            properties.load(in);
            driver = properties.getProperty(JdbcUtils.driver);
            url = properties.getProperty(JdbcUtils.url);
            username = properties.getProperty(JdbcUtils.username);
            password = properties.getProperty(JdbcUtils.password);

            //驱动只需要加载一次
            Class.forName(driver);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //获取连接
    public static Connection getconnection() throws SQLException {
        return DriverManager.getConnection(url, username, password);
    }

    //释放连接
    public void release(Connection conn, Statement st, ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        
    }
}

2、编写增删改的方法,executeUpdate

package com.star.lesson02;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestInsert {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            st = conn.createStatement();//获得SQL的执行对象
            
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)"+
                    "VALUES(4,'kuangshen','123456','24736743@qq.com','202001-01')";
            
            int i = st.executeUpdate(sql);
            
            if(i>0){
                System.out.println("插入成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

package com.star.lesson02;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestDelete {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            st = conn.createStatement();//获得SQL的执行对象

            String sql = "DELETE FROM users WHERE id = 4";

            int i = st.executeUpdate(sql);

            if(i>0){
                System.out.println("删除成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

package com.star.lesson02;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestUpdate {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            st = conn.createStatement();//获得SQL的执行对象

            String sql = "UPDATE users SET `NAME`='lenstar',`email`='1412265423@qq.com' WHERE id=1";

            int i = st.executeUpdate(sql);

            if(i>0){
                System.out.println("修改成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

3、查询excuteQuery

package com.star.lesson02;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestSelect {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            st = conn.createStatement();//获得SQL的执行对象

            String sql = "SELECT `NAME` FROM USER WHERE id = 1";

            rs = st.executeQuery(sql);

            while (rs.next()){
                System.out.println(rs.getString("NAME"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

SQL注入的问题

sql存在漏洞,会被攻击导致数据泄露,SQL会被拼接or

package com.star.lesson02;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class SQL注入 {
    public static void main(String[] args) {
        login("'or'1=1","123456");
    }

    //登录业务
    public static void login(String username, String password) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            st = conn.createStatement();//获得SQL的执行对象

            String sql = "SELECT * FROM users WHERE `NAME` = '"+username+"' AND `PASSWORD`= '"+password+"'";

            rs = st.executeQuery(sql);

            while(rs.next()){
                System.out.print(rs.getString("NAME")+"  ");
                System.out.println(rs.getString("password"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

5、PreparedeStatement对象

PreparedStatement可以防止SQL注入,效率更好

1、新增

package com.star.lesson03;

import com.star.lesson02.utils.JdbcUtils;

import java.util.Date;
import java.sql.*;

public class TestInsert {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();
            //区别
            //使用? 站位符代替参数
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)"+
                    "VALUES(?,?,?,?,?)";

            st = conn.prepareStatement(sql);//预编译SQL,先写sql,然后不执行

            //手动给参数赋值
            st.setInt(1,4);
            st.setString(2,"lenstar");
            st.setString(3,"123456");
            st.setString(4,"1412265423@qq.com");
            //注意点:sql.Date 数据库 java.sql.Date()
            //  util.Date  Java new Date().getTime() 获得时间戳
            st.setDate(5,new java.sql.Date(new Date().getTime()));

            //执行
            int i = st.executeUpdate();
            if(i>0){
                System.out.println("插入成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

2、删除

package com.star.lesson03;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.*;

public class TestDelete {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();
            //区别
            //使用? 站位符代替参数
            String sql = "DELETE FROM users WHERE id = ?";

            st = conn.prepareStatement(sql);//预编译SQL,先写sql,然后不执行

            //手动给参数赋值
            st.setInt(1,4);

            //执行
            int i = st.executeUpdate();
            if(i>0){
                System.out.println("删除成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

3、修改

package com.star.lesson03;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.*;

public class TestUpdate {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();
            //区别
            //使用? 站位符代替参数
            String sql = "UPDATE users SET `NAME`='lenstar',`email`='1412265423@qq.com' WHERE id=?";

            st = conn.prepareStatement(sql);//预编译SQL,先写sql,然后不执行

            //手动给参数赋值
            st.setInt(1,1);

            //执行
            int i = st.executeUpdate();
            if(i>0){
                System.out.println("修改成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

4、查询

package com.star.lesson03;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.*;

public class TestSelect {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();
            String sql = "SELECT `NAME` FROM users WHERE id = ?";

            st = conn.prepareStatement(sql);

            st.setInt(1,2);
            rs = st.executeQuery();

            if(rs.next()){
                System.out.println(rs.getString("NAME"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

5、防止SQL注入

package com.star.lesson03;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.*;

public class 防止SQL注入 {
    public static void main(String[] args) {
        login("''or '1=1'","123456");
    }

    //登录业务
    public static void login(String username, String password) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getconnection();//获取数据库连接
            String sql = "SELECT * FROM users WHERE `NAME` = ? AND `PASSWORD`= ?";

            st = conn.prepareStatement(sql);//获得SQL的执行对象

            st.setString(1,username);
            st.setString(2,password);
            rs = st.executeQuery();

            while(rs.next()){
                System.out.print(rs.getString("NAME")+"  ");
                System.out.println(rs.getString("password"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

7、使用IDEA连接数据库

连接成功后,可以选择数据库

8、事务

ACID原则之前已经说过

代码实现

1、开启事务

2、一组业务执行完毕,提交事务

3、可以在catch语句中显示的定义回滚语句,但默认:失败就会回滚

/*创建账户表*/
CREATE TABLE account(
  id INT PRIMARY KEY AUTO_INCREMENT,
  NAME VARCHAR(40),
  money FLOAT
);

/*插入测试数据*/
insert into account(name,money) values('A',1000);
insert into account(name,money) values('B',1000);
insert into account(name,money) values('C',1000);

package com.star.lesson04;

import com.star.lesson02.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class TestTransaction1 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;
        try{
            conn = JdbcUtils.getconnection();
            //关闭数据库的自动提交,自动提交会开启事务
            conn.setAutoCommit(false);

            String sql1 = "update account set money = money-100 where name = 'A'";
            st = conn.prepareStatement(sql1);
            st.executeUpdate();


            String sql2 = "update account set money = money+100 where name = 'B'";
            st = conn.prepareStatement(sql2);
            st.executeUpdate();


            //业务完毕,提交事务
            conn.commit();
            System.out.println("成功!");

        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            conn.rollback();//如果失败则回滚事务
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

9、数据库连接池

数据库连接--执行完毕--释放

连接--释放 这个过程是十分浪费资源的

池化技术:准备一些预先的资源,过来就连接预先准备好的

比如:

常用连接数为: 10

最小连接数就为: 10

最大连接数就为: 100 即业务最高承载上限

设置等带超时:100ms

编写连接池,实现一个接口 DateSourece

开源数据源实现(拿来即用)

DBCP

C3P0

Druid

使用了这些数据连接池之后,我们在项目开发中就不需要编写连接数据库的代码了!

DBCP

需要用到的jar包:

commons-dbcp-1.4 、 commons-pool-1.6

package com.star.lessson05.utils;

import org.apache.commons.dbcp.BasicDataSourceFactory;

import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils_DBCP {

    private static DataSource dataSource = null;

    static {
        try {
            InputStream in = JdbcUtils_DBCP.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
            Properties properties = new Properties();
            properties.load(in);

            //创建数据源,工厂模式-->创建
            dataSource = BasicDataSourceFactory.createDataSource(properties);


        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //获取连接
    public static Connection getconnection() throws SQLException {
       return dataSource.getConnection();
    }

    //释放连接
    public static void release(Connection conn, Statement st, ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}
package com.star.lessson05;

import com.star.lessson05.utils.JdbcUtils_DBCP;

import java.util.Date;
import java.sql.*;

public class TestDBCP {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils_DBCP.getconnection();
            //区别
            //使用? 站位符代替参数
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)"+
                    "VALUES(?,?,?,?,?)";

            st = conn.prepareStatement(sql);//预编译SQL,先写sql,然后不执行

            //手动给参数赋值
            st.setInt(1,4);
            st.setString(2,"lenstar");
            st.setString(3,"123456");
            st.setString(4,"1412265423@qq.com");
            //注意点:sql.Date 数据库 java.sql.Date()
            //  util.Date  Java new Date().getTime() 获得时间戳
            st.setDate(5,new java.sql.Date(new Date().getTime()));

            //执行
            int i = st.executeUpdate();
            if(i>0){
                System.out.println("插入成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils_DBCP.release(conn,st,rs);
        }
    }
}

C3P0

需要用到的jar包:

c3p0-0.9.5.5、mchange-commons-java-0.2.19

package com.star.lessson05.utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JdbcUtils_C3P0 {

    private static DataSource dataSource = null;

    static {
        try {
//            dataSource = new ComboPooledDataSource();
//            ((ComboPooledDataSource) dataSource).setDriverClass();
//            ((ComboPooledDataSource) dataSource).setUser();
//            ((ComboPooledDataSource) dataSource).setPassword();
//            ((ComboPooledDataSource) dataSource).setJdbcUrl();
//            ((ComboPooledDataSource) dataSource).setMaxPoolSize();
//            ((ComboPooledDataSource) dataSource).setMinPoolSize();
            //创建数据源,工厂模式-->创建
           dataSource = new ComboPooledDataSource("MySQL");//配置文件写法


        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //获取连接
    public static Connection getconnection() throws SQLException {
       return dataSource.getConnection();
    }

    //释放连接
    public static void release(Connection conn, Statement st, ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}
package com.star.lessson05;

import com.star.lessson05.utils.JdbcUtils_C3P0;

import java.util.Date;
import java.sql.*;

public class TsetC3P0 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils_C3P0.getconnection();
            //区别
            //使用? 站位符代替参数
            String sql = "INSERT INTO users(id,`NAME`,`PASSWORD`,`email`,`birthday`)"+
                    "VALUES(?,?,?,?,?)";

            st = conn.prepareStatement(sql);//预编译SQL,先写sql,然后不执行

            //手动给参数赋值
            st.setInt(1,4);
            st.setString(2,"lenstar");
            st.setString(3,"123456");
            st.setString(4,"1412265423@qq.com");
            //注意点:sql.Date 数据库 java.sql.Date()
            //  util.Date  Java new Date().getTime() 获得时间戳
            st.setDate(5,new java.sql.Date(new Date().getTime()));

            //执行
            int i = st.executeUpdate();
            if(i>0){
                System.out.println("插入成功!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils_C3P0.release(conn,st,rs);
        }
    }
}

无论使用什么数据源,本质还是一样的,DateSource接口不会变,方法也不会变!

原文地址:https://www.cnblogs.com/lmx-181028/p/12289449.html