问题：
com.MysqL.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
数据库连接失败
解决：
MysqL版本：5.x
spring.datasource.url=jdbc:MysqL://localhost:3306/resource_sharingdb?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
