servlet及struts2清除页面缓存问题

?????session.setAttribute("logName", logName);//用户写入session

????? //清除页面

???? response.setHeader("Pragma","No-cache");
????? response.setHeader("Cache-Control","no-cache");
?????? response.setHeader("Cache-Control", "no-store");
????? response.setDateHeader("Expires", 0);

????? //跳转页面

??????? RequestDispatcher requestDispatcher = null;
?????? requestDispatcher = request.getRequestDispatcher("index.jsp");
?????? requestDispatcher.forward(request,response);

struts2

????????? HttpServletResponse response = ServletActionContext.getResponse();
????? //清除登陆页面缓存
????? response.setHeader("Pragma","No-cache");
????? response.setHeader("Cache-Control","no-cache");
????? response.setHeader("Cache-Control", "no-store");
????? response.setDateHeader("Expires", 0);

????? //页面重定位,倒计时。
????? String URL = "index.jsp";
????? String content=3+";URL="+URL;//3秒后进入主页
????? response.setHeader("REFRESH",content);

?

这样在调用session.invalidate()后，再按IE或firefox退出按钮时，就会出现页面已过期的提示了。?? response.setHeader("REFRESH",content);?? 是实现倒计时跳转页面。