DataSet生成gb2312编码的xml
 
 DataSet ds = new DataSet("terminal");               

DataTable dt = new DataTable("terminalDev");               

dt.Columns.Add("devClass", typeof(string));              

 dt.Columns.Add("deviceId", typeof(string));               

dt.Columns.Add("version", typeof(string));
DataRow row = dt.NewRow();               

row["devClass"] = txtPlayerName.Text;               

row["deviceId"] = txtPlayerNo.Text;               

row["version"] = txtVersion.Text;
dt.Rows.Add(row);
ds.Tables.Add(dt);
string setPath = String.Format("{0}Terminal\\terminal.xml",GetCurrentPath()) ;     //GetCurrentPath（）是应用程序路径          

if (ds != null)                

{                   

FileStream fs = new FileStream(setPath, FileMode.Create);                   

XmlTextWriter xtr = new XmlTextWriter(fs, System.Text.Encoding.GetEncoding("gb2312"));                   

//加入了下面的指定就可以了                    

xtr.Formatting = Formatting.Indented;                  

 xtr.Indentation = 6;                   

xtr.WriteStartDocument();                   

ds.WriteXml(xtr);                   

xtr.Close();                   

fs.Close();                

}