获取星期一，获取第几周代码,Asp.NET代码库,德仔网

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【Asp.NET】获取星期一，获取第几周
作者:天哲 / 发布于2016/9/13/ 649
protected void Page_Load(object sender, EventArgs e)  
    {  
        DateTime dt1 = Convert.ToDateTime("2012/4/1");  
        //第一天按周日算  
        Response.Write(WeekOfMonth(dt1, true) + "<br/>");  
        //第一天按周一算  
        Response.Write(WeekOfMonth(dt1, false)+"<br/>");  
  
        Response.Write(GetDayOfWeek("2012-04-19", 1)+"<br/>");  
        Response.Write(GetLastDayOfWeek(2012, 4, 1)+"<br/>");  
  
        Response.Write(Convert.ToDateTime("2012-04-01").AddDays(-6)+"<br/>");  
        Response.Write(GetMonday(Convert.ToDateTime("2012-07-01"))+"<br/>");  
        Response.Write(GetSundayM(Convert.ToDateTime("2012-05-31")) + "<br/>");  
    }  
  
    /// <summary>  
    /// 获取某日期是本月的第几周  
    /// </summary>  
    /// <param name="dtSel">DateTime 时间对象</param>  
    /// <param name="sundayStart">true:第一天按周日算 false:第一天按周一算</param>  
    /// <returns>获取第几周</returns>  
    public static int WeekOfMonth(DateTime dtSel, bool sundayStart)  
    {  
        //如果要判断的日期为1号，则肯定是第一周了   
        if (dtSel.Day == 1) return 1;  
        else  
        {  
            //得到本月第一天   
            DateTime dtStart = new DateTime(dtSel.Year, dtSel.Month, 1);  
            //得到本月第一天是周几   
            int dayofweek = (int)dtStart.DayOfWeek;  
            //如果不是以周日开始，需要重新计算一下dayofweek，详细DayOfWeek枚举的定义   
            if (!sundayStart)  
            {  
                dayofweek = dayofweek - 1;  
                if (dayofweek < 0) dayofweek = 7;  
            }  
            //得到本月的第一周一共有几天   
            int startWeekDays = 7 - dayofweek;  
            //如果要判断的日期在第一周范围内，返回1   
            if (dtSel.Day <= startWeekDays) return 1;  
            else  
            {  
                int aday = dtSel.Day + 7 - startWeekDays;  
                return aday / 7 + (aday % 7 > 0 ? 1 : 0);  
            }  
        }  
    }  
  
    /// <summary>  
    /// 输入日期，判断该日期是所在 月、年的第几周  
    /// </summary>  
    /// <param name="datetype">指定日期类型，"m"表示返回指定日期在所在月的第几周，"y"表示返回指定日期在所在年的第几周</param>  
    /// <param name="curdate">指定的日期 string类型</param>  
    /// <param name="daystart">确定日期计算时间，1表示月、年起始周从第一个星期日开始计算，其他表示默认</param>  
    /// <returns></returns>  
    public static string GetWeek(string datetype, string curdate, int daystart)  
    {  
        if (datetype == "m")  
        {  
            int days = Convert.ToDateTime(curdate).Day;  
            int weeks = 0;  
            int dayofweek = 0;  
            weeks = (days - 1) / 7 + 1;  
            dayofweek = Convert.ToInt32(Convert.ToDateTime(curdate).DayOfWeek);  
            DateTime daydate = new DateTime(Convert.ToDateTime(curdate).Year, Convert.ToDateTime(curdate).Month, 1);  
            int da = System.Convert.ToInt32(daydate.DayOfWeek);  
            if (dayofweek < da)  
            {  
                weeks++;  
            }  
            string startdayofweek = daydate.DayOfWeek.ToString();  
            if (daystart == 1)  
            {  
                if (startdayofweek == "Sunday")  
                {  
                    return weeks.ToString();  
                }  
                else  
                {  
                    weeks = weeks - 1;  
                    if (weeks != 0)  
                    {  
                        return weeks.ToString();  
                    }  
                    if (weeks == 0)  
                    {  
                        curdate = System.Convert.ToDateTime(curdate).AddDays(0 - dayofweek).ToString();  
                        string tmpweekofmonth = GetWeek("m", curdate, 1);  
                        return tmpweekofmonth;  
                    }  
                    return null;  
                }  
            }  
            else  
            {  
                return weeks.ToString();  
            }  
            return null;  
        }  
        if (datetype == "y")  
        {  
            System.Globalization.CalendarWeekRule startday = new System.Globalization.CalendarWeekRule();  
            if (daystart == 1)  
            {  
                startday = System.Globalization.CalendarWeekRule.FirstFullWeek;  
            }  
            else  
            {  
                startday = System.Globalization.CalendarWeekRule.FirstDay;  
            }  
            System.Globalization.GregorianCalendar gcyear = new System.Globalization.GregorianCalendar();  
            int weekofyear = gcyear.GetWeekOfYear(Convert.ToDateTime(curdate), startday, DayOfWeek.Sunday);  
            return weekofyear.ToString();  
        }  
        return null;  
    }  
  
    /// <summary>  
    /// 判断某月有多少天  
    /// </summary>  
    /// <remarks>  
    /// 创建人：zhujt<br/>  
    /// 创建日期：2012-04-19 13:51:07<br/>  
    /// </remarks>  
    /// <param name="year">年</param>  
    /// <param name="month">月</param>  
    /// <returns></returns>  
    public static int GetDay(int year, int month)  
    {  
        switch (month)  
        {  
            case 1:  
            case 3:  
            case 5:  
            case 7:  
            case 8:  
            case 10:  
            case 12:  
                return 31;  
            case 4:  
            case 6:  
            case 9:  
            case 11:  
                return 30;  
            case 2:  
                if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)  
                    return 29;  
                else  
                    return 28;  
            default:  
                return 0;  
        }   
    }  
  
    /// <summary>  
    /// 获取某日是周几  
    /// </summary>  
    /// <remarks>  
    /// 创建人：zhujt<br/>  
    /// 创建日期：2012-04-19 13:29:58  
    /// </remarks>  
    /// <param name="date">日期</param>  
    /// <param name="type">显示形式 0：汉字 1：阿拉伯数字</param>  
    /// <returns></returns>  
    public static string GetDayOfWeek(string date, int type)  
    {  
        DateTime dt = Convert.ToDateTime(date);  
        return GetDayOfWeek(type, ref dt);  
    }  
  
    /// <summary>  
    /// 获取某月最后一周是星期几  
    /// </summary>  
    /// <param name="year">年</param>  
    /// <param name="month">月</param>  
    /// <param name="type">显示形式 0：汉字 1：阿拉伯数字</param>  
    /// <returns></returns>  
    public static string GetLastDayOfWeek(int year, int month, int type)  
    {  
        DateTime dt = Convert.ToDateTime(year + "-" + month + "-" + GetDay(year, month));  
        return GetDayOfWeek(1, ref dt);  
    }  
  
    /// <summary>  
    /// 获取日是周几  
    /// </summary>  
    /// <remarks>  
    /// 创建人：zhujt<br/>  
    /// 创建日期：2012-04-19 13:29:58  
    /// </remarks>  
    /// <param name="date">日期</param>  
    /// <param name="type">显示形式 0：汉字 1：阿拉伯数字</param>  
    /// <returns></returns>  
    private static string GetDayOfWeek(int type, ref DateTime dt)  
    {  
        string temp = "";  
        switch (dt.DayOfWeek)  
        {  
            case DayOfWeek.Sunday:  
                temp = type == 0 ? "星期天" : "7";  
                break;  
            case DayOfWeek.Monday:  
                temp = type == 0 ? "星期一" : "1";  
                break;  
            case DayOfWeek.Tuesday:  
                temp = type == 0 ? "星期二" : "2";  
                break;  
            case DayOfWeek.Wednesday:  
                temp = type == 0 ? "星期三" : "3";  
                break;  
            case DayOfWeek.Thursday:  
                temp = type == 0 ? "星期四" : "4";  
                break;  
            case DayOfWeek.Friday:  
                temp = type == 0 ? "星期五" : "5";  
                break;  
            case DayOfWeek.Saturday:  
                temp = type == 0 ? "星期六" : "6";  
                break;  
        }  
        return temp;  
    }  
 
    #region 得到一周的周一和周日的日期  
  
    /// <summary>   
    /// 计算本周的周一日期   
    /// </summary>   
    /// <returns></returns>   
    public static DateTime GetMondayDate()  
    {  
        return GetMondayDate(DateTime.Now);  
    }  
  
    /// <summary>   
    /// 计算本周周日的日期   
    /// </summary>   
    /// <returns></returns>   
    public static DateTime GetSundayDate()  
    {  
        return GetSundayDate(DateTime.Now);  
    }  
  
    ///   <summary>      
    ///   计算某日起始日期（礼拜一的日期）      
    ///   </summary>      
    ///   <param name="someDate">该周中任意一天</param>      
    ///   <returns>返回礼拜一日期，后面的具体时、分、秒和传入值相等</returns>      
    public static DateTime GetMondayDate(DateTime someDate)  
    {  
        int i = someDate.DayOfWeek - DayOfWeek.Monday;  
        if (i == -1) i = 6;//   i值   >   =   0   ，因为枚举原因，Sunday排在最前，此时Sunday-Monday=-1，必须+7=6。      
        TimeSpan ts = new TimeSpan(i, 0, 0, 0);  
        return someDate.Subtract(ts);  
    }  
  
    ///   <summary>      
    ///   计算某日结束日期（礼拜日的日期）      
    ///   </summary>      
    ///   <param name="someDate">该周中任意一天</param>      
    ///   <returns>返回礼拜日日期，后面的具体时、分、秒和传入值相等</returns>      
    public static DateTime GetSundayDate(DateTime someDate)  
    {  
        int i = someDate.DayOfWeek - DayOfWeek.Sunday;  
        if (i != 0) i = 7 - i;//   因为枚举原因，Sunday排在最前，相减间隔要被7减。      
        TimeSpan ts = new TimeSpan(i, 0, 0, 0);  
        return someDate.Add(ts);  
    }  
    #endregion  
  
    /// <summary>  
    /// 从第一周的周一到最后一周的周日  
    /// 比如2012-04-01 是周日 那么2012年4月第一周周一为2012-03-16  
    /// 2012-04-30为周一 那么2012-04-30属于五月份  
    /// 也就是说2012年4月份从2012-03-16到2012-04-29  
    /// </summary>  
    /// <param name="year">年</param>  
    /// <param name="month">月</param>  
    /// <returns></returns>  
    //public static string[] GetEffective(string year, string month)  
    //{   
  
    //}  
 
    #region 获取有效日期  
    /// <summary>  
    /// 根据日期获取某周星期一  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <returns></returns>  
    public static string GetMonday(DateTime dt)  
    {  
        int temp = GetTemp(ref dt);  
  
        if (temp != 1)  // 如果日期不是周一   
            return dt.AddDays(-temp+1).ToString("yyyy-MM-dd");  
        else  
            return dt.ToString("yyyy-MM-dd");   
    }  
  
    /// <summary>  
    /// 根据日期获取某周星期日  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <returns></returns>  
    public static string GetSundayM(DateTime dt)  
    {  
        int temp = GetTemp(ref dt);  
  
        if (temp != 7)  // 如果日期不是周一   
            return dt.AddDays(- temp).ToString("yyyy-MM-dd");  
        else  
            return dt.ToString("yyyy-MM-dd");  
    }  
  
    /// <summary>  
    /// 根据日期获取某周星期日  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <returns></returns>  
    public static string GetSunday(DateTime dt)  
    {  
        int temp = GetTemp(ref dt);  
  
        if (temp != 7)  // 如果日期不是周一   
            return dt.AddDays(7 - temp).ToString("yyyy-MM-dd");  
        else  
            return dt.ToString("yyyy-MM-dd");  
    }  
  
    /// <summary>  
    /// 计算该日期为周几  
    /// </summary>  
    /// <param name="dt"></param>  
    /// <returns></returns>  
    private static int GetTemp(ref DateTime dt)  
    {  
        int temp = 0;  
        switch (dt.DayOfWeek)  
        {  
            case DayOfWeek.Sunday:  
                temp = 7;  
                break;  
            case DayOfWeek.Monday:  
                temp = 1;  
                break;  
            case DayOfWeek.Tuesday:  
                temp = 2;  
                break;  
            case DayOfWeek.Wednesday:  
                temp = 3;  
                break;  
            case DayOfWeek.Thursday:  
                temp = 4;  
                break;  
            case DayOfWeek.Friday:  
                temp = 5;  
                break;  
            case DayOfWeek.Saturday:  
                temp = 6;  
                break;  
        }  
        return temp;  
    }   
     
    #endregion
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