JDBCJDBC连接mySQL数据库常见错误

Posted 2022-11-26 a box of Sweets

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1、正确的代码：

2、正确输出：

3、初学者常犯错误：

（1）第一种出错：驱动类写错，应该是com.mysql.jdbc.Driver

（2）第二种出错：数据库名写错，报：Unknown database 'employeedbs'错误

（3）第三种出错：连接用户名或密码错误：java.sql.SQLException: Access denied for user 'roots'@'localhost' (using password: YES)

（4）第四种出错：连接数据库报：Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

原因：MySQL在高版本需要指明是否进行SSL连接。

解决方案如下：在mysql连接字符串url中加入useSSL=true或者useSSL=false

编辑

正确的代码：

package java_project_jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JDBC_demo 
	static 
		// 加载驱动
		try 
			Class.forName("com.mysql.jdbc.Driver");
		 catch (ClassNotFoundException e) 
			e.printStackTrace();
		
	

	// 连接数据库
	public static Connection getConn() 
		Connection conn = null;
		try 
			conn = DriverManager.getConnection(
					"jdbc:mysql://localhost:3306/db_java?useUnicode=true&characterEncoding=utf8", "root", "12345678");
		 catch (SQLException e) 
			// TODO Auto-generated catch block
			e.printStackTrace();
		
		return conn;
	

	public static void main(String[] args) 
		System.out.println("连接+" + JDBC_demo.getConn());
		;