WCF 返回xml字符串

private string ConvertDataTableToXML(DataTable xmlDS)
        {
            MemoryStream stream = null;
            XmlTextWriter writer = null;
            try
            {
                stream = new MemoryStream();
                writer = new XmlTextWriter(stream, Encoding.UTF8);
                xmlDS.WriteXml(writer);
                int count = (int)stream.Length;
                byte[] arr = new byte[count];
                stream.Seek(0, SeekOrigin.Begin);
                stream.Read(arr, 0, count);
                UTF8Encoding utf = new UTF8Encoding();
                return utf.GetString(arr).Trim();
            }
            catch
            {
                return string.Empty;
            }
            finally
            {
                if (writer != null) writer.Close();
            }
        }

序列化，反序列化：使用XmlSerializer对象来处理.