How to change MySQL timezone in a database connection using Java?

MySQL runs with timezone "GMT+8", but Tomcat with "GMT". When I save datetime to my database, everything seems to be OK, but when I check the datetime value in the database, I see the "GMT" value.

Also when I try get the value from the database the value is changed, seems like the value in the database is taken as "GMT+8", so Java changes the value to "GMT".

I have set the connection URL like this:

useTimezone=true&serverTimezone=GMT

but it does not work.