public string ConvertDataTableToXML(DataTable xmlDS)   
        {   
            MemoryStream stream = null;   
            XmlTextWriter writer = null;   
            try  
            {   
                stream = new MemoryStream();   
                writer = new XmlTextWriter(stream, Encoding.Default);   
                xmlDS.WriteXml(writer);   
                int count = (int)stream.Length;   
                byte[] arr = new byte[count];   
                stream.Seek(0, SeekOrigin.Begin);   
                stream.Read(arr, 0, count);   
                return System.Text.Encoding.GetEncoding("gb2312").GetString(arr).Trim();   
            }   
            catch  
            {   
                return String.Empty;   
            }   
            finally  
            {   
                if (writer != null) writer.Close();   
            }   
        }   
  
        public DataSet ConvertXMLToDataSet(string xmlData)   
        {   
            StringReader stream = null;   
            XmlTextReader reader = null;   
            try  
            {   
                DataSet xmlDS = new DataSet();   
                stream = new StringReader(xmlData);   
                reader = new XmlTextReader(stream);   
                xmlDS.ReadXml(reader);   
                return xmlDS;   
            }   
            catch (Exception ex)   
            {   
                string strTest = ex.Message;   
                return null;   
            }   
            finally  
            {   
                if (reader != null)   
                    reader.Close();   
            }   
        }  


本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/tchjl2007/archive/2010/01/06/5143608.aspx