项目启动，数据库连接错误：SQLNonTransientConnectionException: Could not create connection to database server

原：

<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

修改为：

<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.49</version>
		</dependency>

报错：java.sql.SQLException: com.mysql.cj.jdbc.Driver
修改为：

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.19</version>
		</dependency>