/// <summary>          /// 取中间文本          /// </summary>          /// <param name="SumString">总文本</param>          /// <param name="LeftString">左边文本</param>          /// <param name="RightString">右边文本</param>          /// <returns>找到返回取出的中间文本，没找到返回空</returns>         public static string GetMiddleString(string SumString, string LeftString, string RightString)        {            if (string.IsNullOrEmpty(SumString)) return "";            if (string.IsNullOrEmpty(LeftString)) return "";            if (string.IsNullOrEmpty(RightString)) return "";            int LeftIndex = SumString.IndexOf(LeftString);            if (LeftIndex == -1) return "";            LeftIndex = LeftIndex + LeftString.Length;            int RightIndex = SumString.IndexOf(RightString, LeftIndex);            if (RightIndex == -1) return "";            return SumString.Substring(LeftIndex, RightIndex - LeftIndex);        }