错误码：

java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specifc time zone value if you want to utilize time zone support.

在连接mysql的JDBC的url后面加上服务器的时区：serverTimezone=UTC

jdbc:mysql://localhost:3306/demo?serverTimezone=UTC