changingIPAdd,PortNodynamicallyinservlet

I’m calling a servlet from another servlet by passing the IPaddress and Port Number in the embedded html form tag in the calling servlet.
I want to change the IP Address and port number
dynamically without having to compile the calling servlet again.How do I do it?Is there any way I can store the IPAddress and portno in a file so that I can change there and use that in the calling servlet