///<summary>
 /// 截前后字符(串)
 ///</summary>
 ///<param name="val">原字符串</param>
 ///<param name="str">要截掉的字符串</param>
 ///<param name="all">是否貪婪</param>
 ///<returns></returns>
        private string GetString(string val,string str,bool all)
        {
            return Regex.Replace(val, @"(^(" + str + ")" + (all ? "*" : "") + "|(" + str + ")"+(all ? "*" : "") + "$)", "");
        }

        /// <summary>
        ///
        /// </summary>
        /// <param name="val">原字符串</param>
        /// <param name="c">要截取的字符</param>
        /// <returns></returns>
        private string GetString(string val,char c)
        {
            return val.TrimStart(c).TrimEnd(c);
        }