1. Your Tomcat should be running on Apache server, do not expose Tomcat directly to user
2. Do not run servers as root user, create specific user for it with certain set of privileges
3. Close connection to your database from outside and use localhost for connection
4. If you need to manipulate database learn how to do it from command line or learn how to use ssh to get you in touch with DB and set GUI tool access
5. You can always google for sql injection test, sql injection prevention java. First step ca be using PreparedStatement instead of plane statement, or even better learn Hibernate (HTML or PDF tutorial)
Indeed, I shouldn't have answered this question; from your posting history it seems that you have a knack for biting the hand which tries to help you. Enjoy the ignorance and the bliss which comes with it I guess...