asp.net mvc中的使用者登入驗證過濾器

在WEB專案中建立 類：
public class LoginFilter : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
//HttpContext.Current.Response.Write("OnActionExecuting:正要準備執行Action的時候但還未執行時執行
");
if (HttpContext.Current.Session"admin" == null)
{
//HttpContext.Current.Response.Write("js程式碼");
//HttpContext.Current.Response.End();
//return;

            var context = new ContentResult();
            context.Content = "
"); 
    } 

    public override void OnResultExecuting(ResultExecutingContext filterContext) 
    { 
        // HttpContext.Current.Response.Write("OnResultExecuting:OnResultExecuting也和OnActionExecuted一樣，但前者是在後者執行完後才執行
"); 
    } 

    public override void OnResultExecuted(ResultExecutedContext filterContext) 
    { 
        // HttpContext.Current.Response.Write("OnResultExecuted:是Action執行完後將要返回ActionResult的時候執行
"); 
    } 
} 

使用方法，直接在控制裡方法外面寫，如：
[LoginFilter]
public ActionResult Add()
{
Model.Userinfo loginuser = base.GetLoginUser();
Model.Product pro = new Model.Product() { userid = loginuser.id, username = loginuser.username };
return View(pro);
}