URL rewriting is used for URLs that get sent from the server to the client, whereas POST is a way to transfer data from the client to the server. So the two don't intersect. Can you clarify what you mean?
Yuvraj your sample code has only a doGet() method. Now if a HTTP request uses GET, your code will work fine. But if a POST is used, it will fail, since your servlet does not support it. Refer to arulk's code for a sample implementation of both doGet() and doPost().
Along with the servlet, if you have the security constraints in your DD,then the DD must also support both these methods.