时间转换：DateTimeExtensions

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Beehive.CloudReader.Utility
{
    public static class DateTimeExtensions
    {
        /// <summary>
        ///
        /// </summary>
        /// <param name="dateTime"></param>
        /// <returns></returns>
        public static string ToRelativeDateTimeT(this DateTime dateTime)
        {
            var time = DateTime.Now - dateTime;

            //如果不在同一年 则直接显示年月日
            if ((int.Parse(dateTime.ToString("yyyy")) - int.Parse(DateTime.Now.ToString("yyyy"))) != ) // if (time.TotalDays > 365)
                return dateTime.ToString("yyyy-MM-dd");
            if (time.TotalDays > )
                return dateTime.ToString("M月d日 HH:mm");
            else
            {
                var day = DateTime.Now.Date - dateTime.Date;
                if (day.Days == )
                    return string.Format("前天{0:HH:mm}", dateTime);
                if (day.Days == )
                    return string.Format("昨天{0:HH:mm}", dateTime);
                if (time.TotalMinutes > )
                    return string.Format("今天{0:HH:mm}", dateTime);
                if (time.TotalSeconds > )
                    return string.Format("{0}分钟前", time.Minutes);
                if (time.TotalSeconds <  && time.TotalDays >= )
                    return "刚刚";
                else
                {
                    if (time.Days ==  && dateTime.Date == DateTime.Now.Date)
                        return string.Format("今天{0:HH:mm}", dateTime);
                    if (time.TotalDays >= -)
                        return string.Format("明天{0:HH:mm}", dateTime);
                    if (time.TotalDays < - && time.TotalDays > -)
                        return string.Format("后天{0:HH:mm}", dateTime);
                    return dateTime.ToString("M月d日 HH:mm");
                }
            }
        }

        public static string ToRelativeDateTimeDay(this DateTime dateTime)
        {
            var time = DateTime.Now - dateTime;

            //如果不在同一年 则直接显示年月日
            if ((int.Parse(dateTime.ToString("yyyy")) - int.Parse(DateTime.Now.ToString("yyyy"))) != ) // if (time.TotalDays > 365)
                return dateTime.ToString("yyyy-MM-dd");
            if (time.TotalDays > )
                return dateTime.ToString("M月d日");
            else
            {
                var day = DateTime.Now.Date - dateTime.Date;
                if (day.Days == )
                    return string.Format("前天", dateTime);
                if (day.Days == )
                    return string.Format("昨天", dateTime);
                if (time.TotalMinutes > )
                    return string.Format("{0:HH:mm}", dateTime);
                if (time.TotalSeconds > )
                    return string.Format("{0}分钟前", time.Minutes);
                if (time.TotalSeconds <  && time.TotalDays >= )
                    return "刚刚";
                else
                {
                    if (time.Days ==  && dateTime.Date == DateTime.Now.Date)
                        return string.Format("{0:HH:mm}", dateTime);
                    if (time.TotalDays >= -)
                        return string.Format("明天", dateTime);
                    if (time.TotalDays < - && time.TotalDays > -)
                        return string.Format("后天", dateTime);
                    return dateTime.ToString("M月d日");
                }
            }
        }

        /// <summary>
        ///
        /// </summary>
        /// <param name="dateTime"></param>
        /// <returns></returns>
        public static long ToTimeStamp(this DateTime dateTime)
        {
            var stamp = dateTime.Ticks - new DateTime(, , ).Ticks;
            return stamp /  -  *  * ;
        }

        public static string ToWelcome(this DateTime dateTime)
        {
            var hour = DateTime.Now.Hour;
            var msg = "";
            if (hour >=  && hour < )
            {
                msg = "早上好";
            }
            else if (hour >=  && hour < )
            {
                msg = "上午好";
            }
            else if (hour >=  && hour < )
            {
                msg = "中午好";
            }
            else if (hour >=  && hour < )
            {
                msg = "下午好";
            }
            else
            {
                msg = "晚上好";
            }
            return msg;
        }
    }
}