mysql-connector-java 6版本的jdbc连接问题

使用新版本6的jdbc驱动，会出现下面的问题

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]

就是未识别时区的问题，需要在jdbc连接的url上加上serverTimezone=UTC(世界标准时间)或者GMT（格林威治时间），写成

   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";

关于SSL连接的Warning
SSL 是Secure Sockets Layer（安全套接层），可以在URL后面再添加一个属性useSSL=false就行了
如果你不需要使用SSL连接，你需要通过设置useSSL=false来显式禁用SSL连接。
如果你需要用SSL连接，就要为服务器证书验证提供信任库，并设置useSSL=true

 private String url = "jdbc:mysql://localhost:3306/test?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&serverTimezone=UTC&useSSL=false";