序列化 对象 不需要创建文件的方法？

            UserProfile profile = new UserProfile();

            XmlSerializer serializer = new XmlSerializer(typeof(UserProfile));
            MemoryStream ms = new MemoryStream();
            using(TextWriter w = new StreamWriter( ms,System.Text.Encoding.UTF8 ))
            {
                serializer.Serialize(ms,profile);
            }

            string xml=System.Text.Encoding.UTF8.GetString(ms.ToArray());

   XmlSerializer serializer = new XmlSerializer(typeof(ListItems));
                       XmlDocument doc = new XmlDocument();
                       const string root = @"<?xml version=""1.0""?>";
                       string xmlContent = root + HttpUtility.HtmlDecode(strExtend);
                       doc.LoadXml(xmlContent);
                       System.IO.MemoryStream stream = new System.IO.MemoryStream();
                       doc.Save(stream);
                       stream.Seek(0, SeekOrigin.Begin);
                       XmlSerializerNamespaces xmlns = new XmlSerializerNamespaces();
                       xmlns.Add(String.Empty, String.Empty);
                       ListItems  m_ItemList = serializer.Deserialize(stream) as ListItems;

   XmlSerializer serializer = new XmlSerializer(typeof(List<Option>));
                    string strContent = myRow["Options"].ToString();
                    XmlDocument doc = new XmlDocument();
                    doc.LoadXml(strContent.TrimEnd('？'));
                    System.IO.MemoryStream stream = new System.IO.MemoryStream();
                    doc.Save(stream);
                    stream.Seek(0, SeekOrigin.Begin);

                    List<Option> myList = serializer.Deserialize(stream) as List<Option>;