asp.net创建xml文档

//////////////
   // Create a new XmlTextWriter instance
   XmlTextWriter writer = new XmlTextWriter(Server.MapPath("userInfo.xml"), Encoding.UTF8);

   // start writing!
   writer.WriteStartDocument();
   
   // root
   writer.WriteStartElement("userInfo");

   // Creating the ＜browserInfo＞ element
   writer.WriteStartElement("browserInfo");

   if (Request.UrlReferrer == null)
    writer.WriteElementString("urlReferrer", "none");
   else
    writer.WriteElementString("urlReferrer", Request.UrlReferrer.PathAndQuery);

   writer.WriteElementString("userAgent", Request.UserAgent);
   writer.WriteElementString("userLanguages",  String.Join(", ", Request.UserLanguages));
   writer.WriteEndElement();

   // Creating the ＜visitInfo＞ element
   writer.WriteStartElement("visitInfo");
   writer.WriteAttributeString("timeVisited", DateTime.Now.ToString());
   writer.WriteElementString("ip", Request.UserHostAddress);
   writer.WriteElementString("rawUrl", Request.RawUrl);

   //结束  ＜visitInfo＞
   writer.WriteEndElement();

   //结束根
   writer.WriteEndElement();

   //结束文档
   writer.WriteEndDocument();

   writer.Close();
//////////////