JavaWeb| Java连接MySQL的方法以及遇到的问题

淡淡的烟草味﹌ 2022-02-21 07:47 239阅读 0赞

# 环境 #

*  JDK 1.8+Tomcat v8.5
 *  mysql-connector-java-8.0.14
 *  MySQL 8.0
 *  Eclipse 4.10.0

# 连接MySQL的方法 #

调试没问题的版本：

public static Connection getConnection() {
        
    		Connection connection = null;
    		try {
        
    			Class.forName("com.mysql.cj.jdbc.Driver");
    			String url = "jdbc:mysql://127.0.0.1:3306/user"+"?serverTimezone=GMT%2B8";
    			connection = DriverManager.getConnection(url, "root", "123456");
    			return connection;
    		} catch (ClassNotFoundException nfe) {
        
    			nfe.printStackTrace();
    		} catch (SQLException sqle) {
        
    			sqle.printStackTrace();
    		}
    		return connection;	
    	}

最初遇到各种问题的版本：

public static Connection getConnection() {
        
    		Connection connection = null;
    		try {
        
    			Class.forName("com.mysql.jdbc.Driver");
    			String url = "jdbc:mysql://127.0.0.1:3306/user";
    			connection = DriverManager.getConnection(url, "root", "123456");
    			return connection;
    		} catch (ClassNotFoundException nfe) {
        
    			nfe.printStackTrace();
    		} catch (SQLException sqle) {
        
    			sqle.printStackTrace();
    		}
    		return connection;	
    	}

# 遇到问题 #

**Q1：** Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is`com.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

**A1：** 驱动的类换了个名字

将 
    Class.forName("com.mysql.jdbc.Driver");
    改为
    Class.forName("com.mysql.cj.jdbc.Driver");

**Q2：** java.sql.SQLException: The server time zone value ‘???ú±ê×??±??’ is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.  
**A2：** 因为 mysql 返回的时区有问题，需要显示指定时区：在url上加参数serverTimezone=GMT（如果想返回北京时间，则：serverTimezone=GMT%2B8）

在 url 中加上 "?serverTimezone=GMT%2B8" ，如下：
    String url = "jdbc:mysql://127.0.0.1:3306/user"+"?serverTimezone=GMT%2B8";

**Q3：** 在用户名和密码确定正确的情况下报错：java.sql.SQLException: Access denied for user 'root '@‘localhost’ (using password: YES)  
**A3：** 因为电脑上有 MySQL5.1 和 MySQL8.0，在服务中将5.1对应的服务关掉就好。  
![20190410162606725.png][]

**备注：**  
用 mysql-connector-java-5.1.47 + 服务开的是 MySQL80 也可以，注意用回 Class.forName(“com.mysql.jdbc.Driver”)， 不然会报错ClassNotFound

# 参考 #

[java jdbc 链接本地mysql数据库 报错 Access denied for user ‘root’@‘localhost’ (using password: YES)][java jdbc _mysql_ _ Access denied for user _root_localhost_ _using password_ YES]

[java 配置连接到mysql8.0的一些坑][java _mysql8.0]

[20190410162606725.png]: /images/20220221/582a2c8bb543470281fb718935e924ff.png
[java jdbc _mysql_ _ Access denied for user _root_localhost_ _using password_ YES]: https://www.cnblogs.com/vali/p/6437177.html
[java _mysql8.0]: https://blog.csdn.net/qq_40707685/article/details/83450720