启动报错：

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received 

No appropriate protocol (protocol is disabled or cipher suites are inappropriate)

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

Exception in thread "main" com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

解决：

连接池url的设置问题，加上：

?useUnicode=true

而且

useSSL=false 要设置成false