获取日期是周几

/// <summary>
        /// 获取日期是周几
        /// </summary>
        /// <param name="time"></param>
        /// <returns></returns>
        public static string GetWeekIndexName(this DateTime time)
        {
            return GetLocalWeekDayChs(time.WeekDayIndex());
        }

        /// <summary>
        /// 获取该时间的星期索引
        /// </summary>
        /// <param name="time"></param>
        /// <returns></returns>
        public static int WeekDayIndex(this DateTime time)
        {
            var utcIndex = int.Parse(time.DayOfWeek.ToString("D")); //国际索引
            var localIndex = utcIndex == 0 ? 7 : utcIndex; //本地索引
            return localIndex;
        }