Errore: "mysql_native_password" "Got packets out of order"

[Francesca Bisceglia]

When I try to connect to http://localhost:3306/biblio/index, it shows this message:
J���
5.6.16�N���,|NR/1Ke�ÿ÷�€����������;6;fp$Z{}!)K�mysql_native_passw ord�!��ÿ„#08S01Got packets out of order


I'm writing an app with a servlet running on Tomcat,and in this servlet I connect to database in this way:
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb" , "root" ," ");
The same error message compares when I only write :
http://localhost:3306, that it's weird I guess.

I'm using XAMPP with win8,and all the services (Apache,MySQL and Tomcat) are correctly running.