java 连接MySQL数据库和使用步骤

Posted 2021-07-16 amcomputer

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();
        }

    }
}