logout back button problem

:banghead:
hey all sorry if i am repeating ths topic again, but i could'nt find any help( may be i could'nt understand)
please hav a look , i want a logout button , onclick of which i redirct it to a Action class, once logged out, if i click back i get the information as it was. please suggest me a good cache control technique

this is the java action class

package com.action;

import javax.servlet.http.HttpSession;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
public class LogoutAction extends Action {
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		 HttpSession session = (HttpSession) request.getSession(false);
		 System.out.println("calling logout ction");
		 //response.setDateHeader("Expires", 0);   
		 //response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");   
		 //response.addHeader("Cache-Control", "post-check=0, pre-check=0");   
		 //response.setHeader("Pragma", "no-cache");
		 session.removeAttribute("username");
	       session = null;
//		 session.invalidate();
		   
	      return mapping.findForward("success");

}
}