asp.net cookie

HttpCookie ck = Request.Cookies["cktest"];
            if (ck == null)
            {
                ck = new HttpCookie("cktest");
                ck.Value = "123";

                ck.Expires = DateTime.Now.AddSeconds(20);//20秒的有效期
                Response.Cookies.Add(ck);
                Response.Write("new ck");
            }
            else
            {
                Response.Write(ck.Value.ToString());
            }

            //在一个Cookie中储存多个信息
            /**//*
            HttpCookie cookie = new HttpCookie("cktest");
            cookie.Values.Add("v1","1");
            cookie.Values.Add("v2","2");
            cookie.Values.Add("v3","3");
            Response.AppendCookie(cookie);


            HttpCookie cookies = Request.Cookies["cktest"];
            string value1 = cookies.Values["v1"];
            string value2 = cookies.Values["v2"];

            Response.Write(value1 + value2);

            */