异常信息：com.mysql.jdbc.exceptions.jdbc4.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.
翻译：com.mysql.jdbc.exceptions.jdbc4.CommunicationsException：通信链路失败
原文：https://www.cnblogs.com/suixinsanren/p/10958096.html