//寫入
    protected void Button2_Click(object sender, EventArgs e)
     {
         HttpCookie cookie=new HttpCookie("MyCook");//初使化並設定Cookie的名稱
         DateTime dt=DateTime.Now;
         TimeSpan ts = new TimeSpan(0, 0, 1,0,0);//過期時間為1分鐘
         cookie.Expires = dt.Add(ts);//設定過期時間
         cookie.Values.Add("userid", "userid_value");
         cookie.Values.Add("userid2","userid2_value2");
         Response.AppendCookie(cookie);
        //輸出該Cookie的所有內容
        //Response.Write(cookie.Value); //輸出為：userid=userid_value&userid2=userid2_value2
     }

    //讀取
    protected void Button1_Click(object sender, EventArgs e)
     {

       // HttpCookie cokie = new HttpCookie("MyCook");//初使化
        if (Request.Cookies["MyCook"]!=null)
         {
            //Response.Write("Cookie中鍵值為userid的值:" + Request.Cookies["MyCook"]["userid"]);//整行
            //Response.Write("Cookie中鍵值為userid2的值" + Request.Cookies["MyCook"]["userid2"]);
             Response.Write(Request.Cookies["MyCook"].Value);//輸出全部的值
         }
     }

    //修改Cookie
    protected void Button3_Click(object sender, EventArgs e)
     {
        //獲取客戶端的Cookie物件
         HttpCookie cok = Request.Cookies["MyCook"];
       
        if (cok != null)
         {
         //修改Cookie的兩種方法
             cok.Values["userid"] = "alter-value";
             cok.Values.Set("userid", "alter-value");

          //往Cookie里加入新的內容
              cok.Values.Set("newid", "newValue");
              Response.AppendCookie(cok);
         }

     
     }
    //刪除Cookie
    protected void Button4_Click(object sender, EventArgs e)
     {

         HttpCookie cok = Request.Cookies["MyCook"];
        if (cok != null)
         {
            if (!CheckBox1.Checked)
             {
                 cok.Values.Remove("userid");//移除鍵值為userid的值
             }
            else
             {
                 TimeSpan ts = new TimeSpan(-1, 0, 0, 0);
                 cok.Expires = DateTime.Now.Add(ts);//刪除整個Cookie，只要把過期時間設定為現在
             }
             Response.AppendCookie(cok);
         }
     }

以前寫程式都沒去關注Cookie的應用，因為ASP.NET在客戶端儲存資料的方式比較多，且以前寫的程式都沒有用到Cookie，所以就沒去了解，今天有個程式總是用Cookie出錯。現在在網上查查Cookie的常用方法。
Cookie的用法也和ASP中差不多。比如我們建立一個名為user，值為111的cookie
HttpCookie cookie = new HttpCookie("user");
cookie.Value = "111";
Response.AppendCookie(cookie);
我們取出Cookie值也很簡單
HttpCookie cookie = Request.Cookies["user"];
cookieValue = cookie.Value;
有時候我們想在一個Cookie中儲存多個資訊，那也沒有問題。比如我們在名為user的cookie下加多個資訊
HttpCookie cookie = new HttpCookie("user");
cookie.Values.Add("name","222");
cookie.Values.Add("pwd","333");
cookie.Values.Add("member","admin");
Response.AppendCookie(cookie);
從客戶端獲取取資訊也一樣簡單
HttpCookie cookie = Request.Cookies["user"];
value1 = cookies.Values["name"];
value2 = cookies.Values["pwd"];