// some filter ...
 public   void  doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)  throws  IOException, ServletException {

  filterChain.doFilter(request, response);

  // а здесь уже делаешь то, что тебе надо

}
// ...

 package  com.web.filters;

 import  javax.servlet.*;
 import  javax.servlet.http.*;
 import  java.io.*;

 public   class  SomeFilter  implements  Filter {
   private   static   int  i =  0 ;
   public   void  init(FilterConfig filterConfig)  throws  ServletException {
  }

   public   void  doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)  throws  IOException, ServletException {
    System.out.println(++i);
    filterChain.doFilter(request, response);
    System.out.println(++i);
  }

   public   void  destroy() {
  }
}