XmlDocument xml = new XmlDocument();                    xml.Load(Server.MapPath("~/etao/IncrementIndex.xml"));                                    XmlNode item_ids = xml.GetElementsByTagName("item_ids")[0];                    XmlElement newElement = xml.CreateElement("outer_id");                    newElement.SetAttribute("action", "upload");                    newElement.InnerText =pid;                    item_ids.AppendChild(newElement);                    XmlNodeList modified = xml.GetElementsByTagName("modified");                    modified.Item(0).InnerText = DateTime.Now.ToString();                    xml.Save(Server.MapPath("~/etao/IncrementIndex.xml"));

xml:

       - 
        
       
        1.0
          
       
        2011-7-4 9:42:54
          
       
        官网
          
       
        etao/SellerCats.xml
          
       
        etao/item/
        - 
         
        
         ID1000018452
          //新增加的  
        
         ID1000018413