java的过滤器对session进行检查

 1 private void sendErrorToBrowser(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException{
 2     //请求类型
 3     String requestType = request.getHeader("X-Requested-With");
 4
 5     //ajax请求
 6     if("XMLHttpRequest".equals(requestType)){
 7         response.sendError(HttpServletResponse.SC_UNAUTHORIZED);
 8     }else{
 9         String path = request.getContextPath();
10         String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
11         response.sendRedirect(basePath+"login.jsp");
12     }
13 }

如果是页面请求：

跳转到未登陆处理页面参考：http://www.cnblogs.com/yangzhilong/archive/2013/01/28/2880135.html

如果是ajax请求：

$.ajax({
    type : "POST",
    url : url,
    data : parma,
    dataType : "json",
    success : function(jsonObj) {

    },
    error : function(XMLHttpRequest, textStatus, errorThrown) {
        if(401==XMLHttpRequest.status){
            alert("请登陆后再操作!");
            window.top.location.href = basepath + "login.jsp";
        }else{
            alert("计算失败,服务器发生错误,请联系系统管理员!");
       }
    },
    beforeSend: function(){

    }
});