工作室笔记
处理IE浏览器缓存：
resp.setDateHeader("expires",0);
resp.setHeader("Cache-Control","no-cache");
resp.setHeader("pragma","no-cache");requset延迟跳转页面
resp.setHeader("refresh","5;url=/ServletLession2/login.jsp");带参跳转页面
req.setAttribute("message","用户名或密码不正确，登录失败！");
req.getRequestDispatcher("/ServletLession2/refresh.jsp").forward(req,resp);