清除页面数据
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);