public void AddCookie()
        {
            //方法一：
            HttpCookie Cookie1 = new HttpCookie("CookieName");
            Cookie1.Expires = DateTime.Now.AddDays(1);//设置过期时间
            Cookie1.Value = "Value";
            Response.Cookies.Add(Cookie1);//响应一个Cookies
            //System.Web.HttpContext.Current.Response.Cookies.Add(Cookie1);//作用同 Response.Cookies.Add(Cookie1)，响应一个Cookies
            //方法二：
            Response.Cookies["CookieName"].Value = "Value";
            // Response.Cookies["CookieName"].Values["Key"] = "Value";//存多值
            Response.Cookies["CookieName"].Expires = DateTime.Now.AddDays(1);//设置过期时间
            //方法三：
            HttpCookie cookie3 = new HttpCookie("CookieName");
            DateTime dt = DateTime.Now; //获取当前时间
            TimeSpan ts = new TimeSpan(0, 0, 1, 0, 0);//过期时间为1分钟
            cookie3.Expires = dt.Add(ts);//设置过期时间  
            cookie3.Values.Add("Key", "Value");
            cookie3.Values.Add("Key", "Value");
            //cookie3.Values.Set("Key", "Value");//设置cookie某项的值
            Response.AppendCookie(cookie3); //响应一个Cookies
            //注：如果使用response.Cookies创建cookie就不用写System.Web.HttpContext.Current.Response.Cookies了。
        }

public void ReadCookie()
        {
            //方法一：
            HttpCookie cookies1 = Request.Cookies["CookieName"];
            string Values1 = cookies1.Value;
            //string Values 1= cookies.Values["Key"];//获取多值
            //方法二：
            string Values2 = Request.Cookies["CookieName"].Value;
            //string Values2 = Request.Cookies["CookieName"].Values["Key"];//获取多值
            //方法三：（获取多值）
            string Values3 = Server.UrlDecode(Request.Cookies["CookieName"]["Key"]);
            //System.Web.HttpContext.Current.Request.Cookies["CookieName"];//同Request.Cookies
        }

public void UpdateCookie()
        {
            //修改只需要重新给要修改的cookie赋值就行，这样旧的就会被覆盖掉。
            //所以这里只写一种方法，更多请参考创建cookie
            HttpCookie Cookie = Request.Cookies["CookieName"];
            Cookie.Expires = DateTime.Now.AddDays(1);//设置过期时间
            Cookie.Value = "Value";//设置值
            Response.Cookies.Add(Cookie);//响应一个Cookies
        }

public void DeleteCookie()
        {
            //删除cookie只需修改的cookie的过期时间(expires)过去的时间即可
            //所以这里只写一种方法，更多请参考创建cookie
            HttpCookie Cookie = Request.Cookies["CookieName"];
            Cookie.Expires = DateTime.Now.AddDays(-1);//设置过期时间
            Response.Cookies.Add(Cookie);//响应一个Cookies
        }