使用新版本6的jdbc驅動，會出現下面的問題
Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value 'Öйú±ê׼ʱ¼ä' 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.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_171]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_171]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_171]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_171]
就是未識別時區的問題，需要在jdbc連接的url上加上serverTimezone=UTC(世界標准時間)或者GMT（格林威治時間），寫成
private String url = "jdbc:mysql://localhost:3306/test?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&serverTimezone=UTC";
private String username = "root";
private String password = "root";
private String driverClassName = "com.mysql.cj.jdbc.Driver";
關於SSL連接的Warning
SSL 是Secure Sockets Layer（安全套接層），可以在URL后面再添加一個屬性useSSL=false就行了
如果你不需要使用SSL連接，你需要通過設置useSSL=false來顯式禁用SSL連接。
如果你需要用SSL連接，就要為服務器證書驗證提供信任庫，並設置useSSL=true
private String url = "jdbc:mysql://localhost:3306/test?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&serverTimezone=UTC&useSSL=false";