java 连接MySQL数据库和使用步骤

迈不过友情╰ 2022-10-12 04:27 158阅读 0赞

代码如下：

## 1 加载驱动 。 将mysql驱动注册到DriverManager中去。 ##

Class.forName(“com.mysql.cj.jdbc.Driver”);//也可以用com.mysql.jdbc.Driver

## 2 连接数据库 ##

DriverManager.getConnection(url, name, password);  
//如果关闭自动提交，还需要设置一下

## 3 执行 ##

//若关闭自动提交,需要commit

## 4 关闭数据库 ##

connection.close();

package com.yang.demo01_testJDBC;
    
    import org.junit.Test;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    
    
    public class TestDB { 
        private static Connection connection;
        //public Connection connection = null;
        @Test
        public  void  test() throws SQLException { 
            test_connection();
            System.out.println("测试成功");
        }
    
        public static  void test_connection() throws SQLException { 
            String url = "jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false";
            String name = "root";
            String password = "mysql";//你的密码
    
            //Connection connection = null;
            //1 加载驱动
            try { 
                Class.forName("com.mysql.cj.jdbc.Driver");//也可以用com.mysql.jdbc.Driver
    
    
            //2 连接数据库
                 connection = DriverManager.getConnection(url, name, password);
                //System.out.println("连接成功！");
                //System.out.println(connection);
    
    
            //3 通知数据库开启事务，默认是自动提交:即执行一个语句就提交
            connection.setAutoCommit(false);//关闭自动提交，变为手动
    
            String sql = "UPDATE account set money = money+90 WHERE id =4";
            connection.prepareStatement(sql).execute();
    
            //制作错误
            int i= 1/0;
    
            String sql2 = "UPDATE account set money = money-90 WHERE id =1";
            connection.prepareStatement(sql2).execute();
    
            connection.commit();//以上都提交成功了才成功
                // System.out.println("测试成功");
            } catch (ClassNotFoundException e) { 
                //如果失败，就回滚
                e.printStackTrace();
                connection.rollback();
             connection.close();
            }
    
        }
    }