silverlight操作cookie

using System.Windows.Browser;
namespace SilverlightApplication1
{
    public class CookieHelp
    {
        //添加cookie
        public void SetCookie(string key, string value)
        {
            DateTime expires = DateTime.Now + TimeSpan.FromDays(7); //cookie的有效时间
            string cookie = String.Format("{0}={1};expires={2}", key, value, expires.ToString("R"));
            HtmlPage.Document.SetProperty("cookie", cookie);
        }

        //删除cookie，使用一个过期的cookie替代
        public void DelCookie(string key)
        {
            DateTime expires = DateTime.Now - TimeSpan.FromDays(1); //将有效时间换成昨天
            string cookie = String.Format("{0}=;expires={1}", key, expires.ToString("R"));
            HtmlPage.Document.SetProperty("cookie", cookie);
        }

        //获取cooike对应键值
        public string GetCookie(string key)
        {
            string[] cookies = HtmlPage.Document.Cookies.Split(';');//cookie里含多对值,将值按;分割
            foreach (string cookie in cookies)
            {
                string[] value = cookie.Split('=');//获取=两边的值
                if (value.Length == 2)
                {
                    if (value[0].ToString() == key)//判断键名
                    {
                        return value[1];//返回键值
                    }
                }
            }
            return "";
        }

        //获取cookie键值linq表达式
        public string GetCookie(string key)
        {
            String[] cookies = HtmlPage.Document.Cookies.Split(';');             
            String result = (from c in cookies
                             let keyValues = c.Split('=')
                             where keyValues.Length == 2 && keyValues[0].Trim() == key.Trim()
                             select keyValues[1]).FirstOrDefault();            
            return result;           
        }      
    }
}