非.aspx/.aspx.cs 中引用Response,Request等使用类请使用，
HttpResponse resp = System.Web.HttpContext.Current.Response;
HttpRequest req = System.Web.HttpContext.Current.Request;
HttpServerUtility server = System.Web.HttpContext.Current.Server;
HttpSessionState session = System.Web.HttpContext.Current.Session;
// ....
所有这些使用类实例都作为Page中对应的实例属性公开
