/// <summary>
        /// 將物件轉換成json字串
        /// </summary>
        /// <param name="obj">物件</param>
        /// <param name="dateFormat">物件中日期要轉換的格式</param>
        /// <returns></returns>
        public static String Json(object obj, String dateFormat = "yyyy-MM-dd")
        {
            IsoDateTimeConverter timeConverter = new IsoDateTimeConverter();
            timeConverter.DateTimeFormat = dateFormat;
            var jSetting = new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore,Converters={timeConverter}};
            var strjson=JsonConvert.SerializeObject(obj,Newtonsoft.Json.Formatting.Indented,jSetting);

            strjson = Regex.Replace(strjson, @"\\/Date\((\d+)\)\\/

", match =>
            {
                DateTime dt = new DateTime(1970, 1, 1);
                dt = dt.AddMilliseconds(long.Parse(match.Groups[1].Value));
                dt = dt.ToLocalTime();
                return dt.ToString(dateFormat);
            });
            return strjson;
        }