C#字符串序列化与反序列化

private void cookieSerilizse()
        {
            //序列化
            string str = "I'm a test data";
            IFormatter fm = new BinaryFormatter();//实例化一个二进制序列化对象
            MemoryStream  ms=new MemoryStream();//实例如化一个内存流对象
            fm.Serialize(ms, str);//进行序列化
            ms.Seek(0, SeekOrigin.Begin);//指定当前流的位置
            StreamReader sr = new StreamReader(ms);//实例化流的新实例
            string st = sr.ReadToEnd();//将流中的数据全部读出并赋给字符串变量
            sr.Close();
            HttpCookie hc = new HttpCookie("trent");//创建COOKIE
            hc.Value = Server.UrlEncode(st);//将数据编码后赋给COOKIE
            hc.Expires = DateTime.Now.AddMinutes(5);//设置COOKIE的有效期
            Response.Cookies.Add(hc);//将数据写入COOKIE

            //反序列化
            HttpCookie hr = Request.Cookies["trent"];
            Response.Write("<h1>未反序列化:</h1>"+hr.Value+"<br>");
            string stri = Server.UrlDecode(hr.Value.ToString());
            byte[] bt = System.Text.Encoding.Default.GetBytes(stri);
            Stream smn = new MemoryStream(bt);
            IFormatter fmn = new BinaryFormatter();
            string strn =(string) fmn.Deserialize(smn);

            Response.Write("<h1>已反序列化:</h1>"+strn+"<b>");
        }