【jdbc连接错误】The driver has not received any packets from the server.

错误：The driver has not received any packets from the server.

大概率是MySQL版本与mysql-connector-java版本对应不上。
一开始百度搜的其他方法都试过了还是没用，后来发现自己MySQL版本是5.7，而pom.xml中的mysql-connector-java的版本为8.0的。
将pom.xml中的mysql-connector-java改为：

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.25</version>
		</dependency>

再将数据源的yml文件的driver-class-name去掉cj：

spring:
    datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        druid:
            driver-class-name: com.mysql.cj.jdbc.Driver

改为

spring:
    datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        druid:
            driver-class-name: com.mysql.jdbc.Driver