using System;
using System.Web;

namespace WebApplication4
{
    /// <summary>
    /// ASP.NET Cookie 操作, 以用戶登錄退出為例, 實現Cookie的獲取, 設置, 清除
    /// </summary>
    public partial class Default : System.Web.UI.Page
    {
        /// <summary>
        /// 載入, 獲取Cookie
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Page_Load(object sender, EventArgs e)
        {
            string user = "";
            // 讀取Cookie
            HttpCookie cookie = HttpContext.Current.Request.Cookies["User"];
            if (cookie != null)
            {
                user = cookie.Value;
            }
            Response.Write("當前登錄用戶: " + user);
        }

        /// <summary>
        /// 登錄, 設置Cookie
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnLogin_Click(object sender, EventArgs e)
        {
            // 設置Cookie, 5分鐘后過期
            HttpCookie cookie = new HttpCookie("User")
            {
                Value = "Admin",
                Expires = DateTime.Now.AddMinutes(+5)
            };
            HttpContext.Current.Response.Cookies.Add(cookie);

            // 如果未設置Cookie過期時間, 則Cookie的有效期只在當前頁面, 關閉瀏覽器再次進入就無效了過期了
            //HttpCookie cookie = new HttpCookie("User")
            //{
            //    Value = "Admin"
            //};
            //HttpContext.Current.Response.Cookies.Add(cookie);

            // 再次刷新頁面
            HttpContext.Current.Response.Redirect("Default.aspx", false);
        }

        /// <summary>
        /// 退出, 清除Cookie
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnLogOff_Click(object sender, EventArgs e)
        {
            // 清除Cookie
            HttpCookie cookie = HttpContext.Current.Request.Cookies["User"];
            if (cookie != null)
            {
                HttpContext.Current.Response.Cookies["User"].Expires = DateTime.Now.AddSeconds(-1);
            }

            // 再次刷新頁面
            HttpContext.Current.Response.Redirect("Default.aspx", false);
        }
    }
}