像这样写时：Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1/mydb,"root","root");
出现Warning: Establishing SSL connection without server's identity verification is not recommended [duplicate]这个警告，改成下面这样就好了：
Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1/mydb?useSSL=false","root","root");
