用datatable 读写xml 及追加数据到xml

 /// <summary>
        /// 写错误日志
        /// </summary>
        /// <param name="ex"></param>
        public static void WriteErrorLog(Exception ex)
        {
           
            DataTable dt = new DataTable("ErrorLog");
            dt.Columns.Add("Date");
            dt.Columns.Add("Message");
            DataRow dr = dt.NewRow();
            dr["Date"] = DateTime.Now;
            dr["Message"] = ex.Message;
            dt.Rows.Add(dr);
            string path = Config.GetConfigValue("BASE_ERROR_FOLDER");//路径
            //目录是否存在
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            string fullPath = path + "errorLog.xml";
            //文件是否存在
            if (!File.Exists(fullPath))
            {
                dt.WriteXml(fullPath, XmlWriteMode.WriteSchema);
               
            }
            else {
                AppandXml(ex, fullPath);//存在，则追加
            }
           
        }

/// <summary>
        /// 追加写入XML文件
        /// </summary>
        /// <param name="ex"></param>
        /// <param name="fullPath">文件全路径</param>
        public static void AppandXml(Exception ex, string fullPath)
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(fullPath);
            XmlNode root = xmlDoc.SelectSingleNode("NewDataSet");//查找到根目录
            XmlElement errorLog_ele = xmlDoc.CreateElement("ErrorLog");

            XmlElement date_ele = xmlDoc.CreateElement("Date");
            date_ele.InnerText = DateTime.Now.ToString();
            errorLog_ele.AppendChild(date_ele);

            XmlElement message_ele = xmlDoc.CreateElement("Message");
            message_ele.InnerText =ex.Message;
            errorLog_ele.AppendChild(message_ele);

            root.AppendChild(errorLog_ele);
            xmlDoc.Save(fullPath);
        }
       

string filePath = (string)(Config.GetDataPath(StatType, Year, Week));

            DataTable dt = new DataTable();
            dt.ReadXml(filePath);