XmlDocument doc = new XmlDocument();             try             {                 doc.Load("new.xml");             }             catch             {                 XmlTextWriter xtw = new XmlTextWriter("new.xml", Encoding.UTF8);                 //新建XML文件                         xtw.WriteStartDocument();                 xtw.WriteStartElement("gnode");                 // gnode根节点                                  xtw.WriteStartElement("myxm1");                 // gnode根节点下的元素myxmls                              xtw.WriteEndElement();                 xtw.WriteEndElement();                 xtw.WriteEndDocument();                 xtw.Close();                 doc.Load("new.xml");             }             XmlNode xn = doc.DocumentElement;             //找到根节点                  XmlElement xe = doc.CreateElement("myxml2");             //在根节点下创建元素，如果是属性，则用XmlAttribute；              xe.InnerText = "hahaha";             //给子节点写入文本节点（值）                  xn.AppendChild(xe);             //根节点将其纳入                      doc.Save("new2.xml");             //利用XmlDocument保存文件         }

   using (SqlConnection con = new SqlConnection("Server=.;DataBase=HGSTUDY;uid=sa;pwd=yao"))             {                 con.Open();                 SqlCommand command = new SqlCommand("select * from GL_STUDY", con);                 command.CommandType = CommandType.Text;                 DataSet ds = new DataSet("DATASET");                 //DATASET将成为XML文件中的根节点名称，否则系统将其命名为NewDataSet                       SqlDataAdapter sda = new SqlDataAdapter();                 sda.SelectCommand = command;                 sda.Fill(ds, "DATATABLE");                 //DATATABLE为所生成XML文件中的子节点名称，否则系统将其命名为Table。                    ds.WriteXml("dbxml.xml");                 // DataSet的方法WriteXml将数据写入到XML文件，就是这么一句话。如果不保存到文件，直接ds.GetXML()                   }

[XmlRoot("Truck")]                 //----设置作为XML中的根元素名称           public Truck()            { }                      [XmlAttribute("id")]         //--------设置作为xml中的属性             public int ID                 {                         get{return this._id;}                  set { this._id = value; }                }               [XmlElement("chepai")]         //------设置作为XML中的元素（默认状态）           public string cheID            {                       get {                 return this._cheID;             }                     set {                 this._cheID = value;             }                }                private int _id = 0;          private string _cheID = "";  

class XXX {                  XmlSerializer ser = new XmlSerializer(Type.GetType("forxml.truck"));                   Truck tr = new Truck();                     tr.ID = 1;                    tr.cheID = "赣A T34923";            }