It is likely that you don't need tomcat on android. After all tomcat is (apart from everything else) a web server. This means that the phone your app is run within should be serving requests from other clients. I doubt you can make sure your phone IP is fixed, and even if that's the case, phones are not meant to be servers.
What I suspect you have done is - you've implemented some functionality in the context of JSP and servlets, but this functionality can easily be run without jsp/servlets. Remove the servlet-api.jar from your classpath and make your functionality work without these. Then you can easily use it in an android app.