C# Net 计算周（可正推和逆推）

C# Net 计算周（可正推和逆推）

拷贝代码（方法）：

        /// <summary>
        /// 计算周
        /// </summary>
        /// <param name="Time">一个时间点，用来计算周（必须有年月日）</param>
        /// <param name="WeekCount">推测的周数量</param>
        /// <param name="Add">是正推（加）还是负推（减）</param>
        /// <param name="ThisWeek">是否包含此时间点所在的周</param>
        /// <returns></returns>
        public static List<TimeWeek> GetTimeWeek(DateTime Time, int WeekCount, bool Add, bool ThisWeek)
        {
            List<TimeWeek> timeWeeks = new List<TimeWeek>();
            TimeWeek week = new TimeWeek();
            week.Week = ConvertWeekOfYear(Time);
            int dayOfTheWeek = (int)Time.DayOfWeek;
            int CountLength = dayOfTheWeek == 0 ? 7 : dayOfTheWeek;
            //如果包含当前周，就加入到返回列表.同时推算的周数减一
            if (ThisWeek)
            {
                DateTime mon = Time.Date.AddDays(1 - CountLength);//本周一
                DateTime sun = Time.Date.AddDays(7 - CountLength).AddDays(1).AddSeconds(-1);//本周日
                week.BeginTime = mon;
                week.EndTime = sun;
                timeWeeks.Add(week);
                WeekCount--;
            }
            if (Add)
            {
                for (int i = 1; i <= WeekCount; i++)
                {
                    DateTime mon = Time.Date.AddDays(1 - CountLength + i * 7);//往前推的周数计算星期一
                    DateTime sun = Time.Date.AddDays(7 - CountLength + i * 7).AddDays(1).AddSeconds(-1);
                    TimeWeek Downweek = new TimeWeek();
                    Downweek.Week = ConvertWeekOfYear(mon);
                    Downweek.BeginTime = mon;
                    Downweek.EndTime = sun;
                    timeWeeks.Add(Downweek);
                }
            }
            else
            {
                for (int i = 1; i <= WeekCount; i++)
                {
                    DateTime mon = Time.Date.AddDays(1 - CountLength - i * 7);//往回推的周数计算星期一
                    DateTime sun = Time.Date.AddDays(7 - CountLength - i * 7).AddDays(1).AddSeconds(-1);
                    TimeWeek upweek = new TimeWeek();
                    upweek.Week = ConvertWeekOfYear(mon);
                    upweek.BeginTime = mon;
                    upweek.EndTime = sun;
                    timeWeeks.Add(upweek);
                }
            }
            return timeWeeks.OrderBy(t => t.BeginTime).ToList();
        }

        /// <summary>
        /// 返回指定年份的周
        /// </summary>
        /// <param name="time"></param>
        /// <returns></returns>
        public static int ConvertWeekOfYear(DateTime time)
        {
            System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
            return gc.GetWeekOfYear(time, System.Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Monday);
        }

拷贝代码（自定义类）：

    /// <summary>
    /// 时间周
    /// </summary>
    public class TimeWeek
    {
        /// <summary>
        /// 第几周（从开年的1月1日计算）
        /// </summary>
        public int Week { get; set; }
        /// <summary>
        /// 这周的开始时间（一般是周一）
        /// </summary>
        public DateTime BeginTime { get; set; }
        /// <summary>
        /// 这周的结束时间（一般是周日）
        /// </summary>
        public DateTime EndTime { get; set; }
    }