关于Cookies

(一)用法：
response.cookies用来设置cookies  
request.cookies用来读取cookies  

HttpCookie cookie = new HttpCookie["zh"];
cookie.Value = "中华人民共和国";
Response.AppendCookie(cookie);

取出Cookie值也很简单

HttpCookie cookie = Request.Cookies["zh"];
cookieValue = cookie.Value;
（二）问题处理：
1、在应用程序中有时会出现cookie混乱的问题，主要问题在RemoveCookie上，解决办法：
       /// <summary>
       /// 移除cookie,将Request和Response两个集合中的都清理
       ///  Code by KentLi
       /// </summary>
       /// <param name="cookieName">cookie名称</param>
      public void RemoveCookie(string cookieName)
      {
              HttpCookie Cookie =  HttpContext.Current.Request.Cookies[cookieName];
              if (Cookie != null)
              {
                    //过期时间设置为立即过期       
                     Cookie.Expires=  DateTime.Now;
                     HttpContext.Current.Request.Cookies.Remove(cookieName);
              }
              Cookie =  HttpContext.Current.Response.Cookies[cookieName];
              if (Cookie != null)
              {
                    Cookie.Expires=  DateTime.Now;
      HttpContext.Current.Response.Cookies.Remove(cookieName);
              }
      }
              public void appendcook(string cookies,string cookiesvalue,int days)
              {
                     HttpCookie usercookie=new HttpCookie(cookies,cookiesvalue);
                    usercookie.Expires = DateTime.Now.AddDays(days);
                     HttpContext.Current.Response.Cookies.Add(usercookie);
              }
2、中文cookie的问题，在Windows 2000正常，在Windows 2003有时会不正常(几率很小，但的确存在)，采用：
Server.UrlEncode();  
Server.UrlDecode();
编码和解码。

Cookie["MyCookie"] = Server.UrlEncode("中文")
Response.Write(Server.UrlDecode(Request.Cookies("MyCookie").Value()))

HttpContext.Current.Response.Cookies
HttpContext.Current.Request.Cookies

分别是需要写回用户客户端和从用户客户端读取的Cookie集合。

当修改Cookie的时候，为了保证同一个Asp.net 页面能访问修改后的Cookie，就必须同时修改这两个集合中的Cookie。