C# DateTime 转文本，例如：1年前，3个月前，3周前，6天前，15小时前，35分钟前

#region 时间转文本

        public static string ToRead(this DateTime src)
        {
            return ToRead(src as DateTime?);
        }
        public static string ToRead(this DateTime? src)
        {
            string result = null;
            if (src.HasValue)
            {
                result = DateTimeToStr2(src.Value);
            }
            return result;
        }

        private static string DateTimeToStr1(DateTime src)
        {
            string result = null;
            TimeSpan timeSpan = DateTime.Now - src;
            if (((int)timeSpan.TotalDays) > 365) //大于一年的
            {
                int years = (int)timeSpan.TotalDays / 365;
                //if (timeSpan.TotalDays % 365 > 0) years++;
                result = string.Format("{0}年之前", years);
            }
            else if (((int)timeSpan.TotalDays) > 30) //大于一个月的
            {
                int months = (int)timeSpan.TotalDays / 30;
                //if (timeSpan.TotalDays % 30 > 0) months++;
                result = string.Format("{0}个月前", months);
            }
            else if (((int)timeSpan.TotalDays) > 7) //大于一周的
            {
                int weeks = (int)timeSpan.TotalDays / 7;
                //if (timeSpan.TotalDays % 7 > 0) weeks++;
                result = string.Format("{0}周前", weeks);
            }
            else if (((int)timeSpan.TotalDays) > 0) //大于 0 天的
            {
                result = string.Format("{0}天前", (int)timeSpan.TotalDays);
            }
            else if (((int)timeSpan.TotalHours) > 0) //一小时以上的
            {
                result = string.Format("{0}小时", (int)timeSpan.TotalHours);
            }
            else if (((int)timeSpan.TotalMinutes) > 0) //一分钟以上的
            {
                result = string.Format("{0}分钟前", (int)timeSpan.TotalMinutes);
            }
            else if (((int)timeSpan.TotalSeconds) >= 0 && ((int)timeSpan.TotalSeconds) <= 60) //一分钟内
            {
                result = "刚刚";
            }
            else
            {
                result = src.ToString("yyyy-MM-dd HH:mm:ss");
            }
            return result;
        }

        private static string DateTimeToStr2(DateTime src)
        {
            string result = null;

            long currentSecond = (long)(DateTime.Now - src).TotalSeconds;

            long minSecond = 60;                //60s = 1min
            long hourSecond = minSecond * 60;   //60*60s = 1 hour
            long daySecond = hourSecond * 24;   //60*60*24s = 1 day
            long weekSecond = daySecond * 7;    //60*60*24*7s = 1 week
            long monthSecond = daySecond * 30;  //60*60*24*30s = 1 month
            long yearSecond = daySecond * 365;  //60*60*24*365s = 1 year

            if (currentSecond >= yearSecond)
            {
                int year = (int)(currentSecond / yearSecond);
                result = string.Format("{0}年前", year);
            }
            else if (currentSecond < yearSecond && currentSecond >= monthSecond)
            {
                int month = (int)(currentSecond / monthSecond);
                result = string.Format("{0}个月前", month);
            }
            else if (currentSecond < monthSecond && currentSecond >= weekSecond)
            {
                int week = (int)(currentSecond / weekSecond);
                result = string.Format("{0}周前", week);
            }
            else if (currentSecond < weekSecond && currentSecond >= daySecond)
            {
                int day = (int)(currentSecond / daySecond);
                result = string.Format("{0}天前", day);
            }
            else if (currentSecond < daySecond && currentSecond >= hourSecond)
            {
                int hour = (int)(currentSecond / hourSecond);
                result = string.Format("{0}小时前", hour);
            }
            else if (currentSecond < hourSecond && currentSecond >= minSecond)
            {
                int min = (int)(currentSecond / minSecond);
                result = string.Format("{0}分钟前", min);
            }
            else if (currentSecond < minSecond && currentSecond >= 0)
            {
                result = "刚刚";
            }
            else
            {
                result = src.ToString("yyyy-MM-dd HH:mm:ss");
            }
            return result;
        }

        #endregion