DatetimeHelper，时间帮助类

public static class DateTimeEx
{
/// <summary>
/// 得到中文形式的日期
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static string GetChineseDate(DateTime dt)
{
return dt.Year.ToString() + "年" + dt.Month.ToString() + "月" + dt.Day.ToString() + "日";
}

/// <summary>
/// 得到中文形式的时间
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static string GetChineseTime(DateTime dt)
{
return dt.Hour.ToString() + "点" + dt.Minute.ToString() + "分" + dt.Second.ToString() + "秒";
}

/// <summary>
/// 得到中文形式的日期时间
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static string GetChineseDateTime(DateTime dt)
{
return GetChineseDate(dt) + GetChineseTime(dt);
}

/// <summary>
/// 得到某月的最后一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回最后一天的日期</returns>
public static DateTime GetLastDateOfMonth(DateTime dt)
{
return GetLastDateOfMonth(dt.Year, dt.Month);
}

/// <summary>
/// 得到某月的最后一天
/// </summary>
/// <param name="year">年</param>
/// <param name="month">月</param>
/// <returns>返回最后一天的日期</returns>
public static DateTime GetLastDateOfMonth(int year, int month)
{
if (month < 1) month = 1;
if (month > 12) month = 12;
return (new DateTime(year, month, 1)).AddMonths(1).AddDays(-1);
}

/// <summary>
/// 得到某月的最后一豪秒
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回最后一豪秒的日期</returns>
public static DateTime GetLastDateTimeOfMonth(DateTime dt)
{
return GetLastDateTimeOfMonth(dt.Year, dt.Month);
}

/// <summary>
/// 得到某月的最后一豪秒
/// </summary>
/// <param name="year">年</param>
/// <param name="month">月</param>
/// <returns>返回最后一豪秒的日期</returns>
public static DateTime GetLastDateTimeOfMonth(int year, int month)
{
if (month < 1) month = 1;
if (month > 12) month = 12;
return (new DateTime(year, month, 1)).AddMonths(1).AddSeconds(-1);
}

/// <summary>
/// 得到某月的第一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回第一天的日期</returns>
public static DateTime GetFirstDateOfMonth(DateTime dt)
{
return GetFirstDateOfMonth(dt.Year, dt.Month);
}

/// <summary>
/// 得到某月的第一天
/// </summary>
/// <param name="year">年</param>
/// <param name="month">月</param>
/// <returns>返回第一天的日期</returns>
public static DateTime GetFirstDateOfMonth(int year, int month)
{
if (month < 1) month = 1;
if (month > 12) month = 12;
return new DateTime(year, month, 1);
}

/// <summary>
/// 得到某年的第一天
/// </summary>
/// <param name="year">年</param>
/// <returns>返回第一天的日期</returns>
public static DateTime GetFirstDateOfYear(int year)
{
return new DateTime(year, 1, 1);
}

/// <summary>
/// 得到某年的第一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回第一天的日期</returns>
public static DateTime GetFirstDateOfYear(DateTime dt)
{
return GetFirstDateOfYear(dt.Year);
}

/// <summary>
/// 得到某年的最后一天
/// </summary>
/// <param name="year">年</param>
/// <returns>返回最后一天的日期</returns>
public static DateTime GetLastDateOfYear(int year)
{
return new DateTime(year, 12, 31);
}

/// <summary>
/// 得到某年的最后一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回最后一天的日期</returns>
public static DateTime GetLastDateOfYear(DateTime dt)
{
return GetLastDateOfYear(dt.Year);
}

/// <summary>
/// 得到某年的最后一毫秒
/// </summary>
/// <param name="year">年</param>
/// <returns>返回最后一毫秒的日期时间对象</returns>
public static DateTime GetLastDateTimeOfYear(int year)
{
return new DateTime(year + 1, 1, 1).AddSeconds(-1);
}

/// <summary>
/// 得到某年的最后一毫秒
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回最后一毫秒的日期时间对象</returns>
public static DateTime GetLastDateTimeOfYear(DateTime dt)
{
return GetLastDateTimeOfYear(dt.Year);
}

/// <summary>
/// 计算某段时间内，每月的天数
/// </summary>
/// <param name="beginTime">开始时间</param>
/// <param name="endTime">结束时间</param>
/// <returns>返回天数</returns>
public static float GetDaysOfMonth(DateTime beginTime, DateTime endTime)
{
float days;
if (beginTime.Year == endTime.Year && beginTime.Month == endTime.Month)
{
//如果是同一个月，返回这个月的天数
DateTime t1 = new DateTime(beginTime.Year, beginTime.Month, 1);
DateTime t2 = t1.AddMonths(1);
TimeSpan interval = t2.Subtract(t1);
days = interval.Days;
}
else if (beginTime.Year == endTime.Year)
{
//如果是同一年，返回这一年的平均月天数
DateTime t1 = new DateTime(beginTime.Year, 1, 1);
DateTime t2 = new DateTime(beginTime.Year + 1, 1, 1);
TimeSpan interval = t2.Subtract(t1);
days = (float)(1.0 * interval.Days / 12);
}
else
{
//否则返回每4年的平均月天数
days = (float)((365.0 * 3 + 366) / 48);
}
return days;
}

/// <summary>
/// 得到某日所在周的第一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回某日所在周的第一天</returns>
public static DateTime GetFirstDateOfWeek(DateTime dt)
{
int days = (int)dt.DayOfWeek;
TimeSpan ts = new TimeSpan(days, 0, 0, 0);
return dt.Date - ts;
}

/// <summary>
/// 得到某日所在周的最后一天
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回某日所在周的最后一天</returns>
public static DateTime GetLastDateOfWeek(DateTime dt)
{
int days = 6 - (int)dt.DayOfWeek;
TimeSpan ts = new TimeSpan(days, 0, 0, 0);
return dt.Date + ts;
}

/// <summary>
/// 得到某日所在周的最后一豪秒
/// </summary>
/// <param name="dt">日期</param>
/// <returns>返回某日所在周的最后一毫秒</returns>
public static DateTime GetLastDateTimeOfWeek(DateTime dt)
{
int days = 6 - (int)dt.DayOfWeek;
TimeSpan ts = new TimeSpan(days, 0, 0, 0);
DateTime lastDate = dt.Date + ts;
return new DateTime(lastDate.Year, lastDate.Month, lastDate.Day, 23, 59, 59, 59);
}

/// <summary>
/// 得到本月已经过去的天数
/// </summary>
/// <returns>返回本月已经过去的天数</returns>
public static int GetThisMonthPastDays()
{
int days;
DateTime today = DateTime.Today;
DateTime firstDayOfCurMonth = DateTimeEx.GetFirstDateOfMonth(today);
TimeSpan ts = today - firstDayOfCurMonth;
days = (int)ts.TotalDays;
if (days < 1)
days = 1;
return days;
}

/// <summary>
/// 得到本年已经过去的天数
/// </summary>
/// <returns>返回本年已经过去的天数</returns>
public static int GetThisYearPastDays()
{
int days;
DateTime today = DateTime.Today;
DateTime firstDayOfCurYear = DateTimeEx.GetFirstDateOfYear(today);
TimeSpan ts = today - firstDayOfCurYear;
days = (int)ts.TotalDays;
if (days < 1) days = 1;
return days;
}

/// <summary>
/// 得到本周已经过去的天数
/// </summary>
/// <returns>返回本周已经过去的天数</returns>
public static int GetThisWeekPastDays()
{
int days;
DateTime today = DateTime.Today;
DateTime firstDayOfCurWeek = DateTimeEx.GetFirstDateOfWeek(today);
TimeSpan ts = today - firstDayOfCurWeek;
days = (int)ts.TotalDays;
if (days < 1) days = 1;
return days;
}

/// <summary>
/// 得到某日所在季度的第一天
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static DateTime GetFirstDateOfQuarter(DateTime dt)
{
int year = dt.Year;
int month;
int dtMonth = dt.Month;
if (dtMonth == 1 || dtMonth == 2 || dtMonth == 3)
month = 1;
else if (dtMonth == 4 || dtMonth == 5 || dtMonth == 6)
month = 4;
else if (dtMonth == 7 || dtMonth == 8 || dtMonth == 9)
month = 7;
else
month = 10;
return new DateTime(year, month, 1);
}

/// <summary>
/// 得到某日所在季度的最后一天
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static DateTime GetLastDateOfQuarter(DateTime dt)
{
return GetFirstDateOfQuarter(dt).AddMonths(3).AddDays(-1); //即下一季度第1天减1天
}

/// <summary>
/// 得到某日所在季度的最后一天的最后一秒
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static DateTime GetLastDateTimeOfQuarter(DateTime dt)
{
return GetFirstDateOfQuarter(dt).AddMonths(3).AddSeconds(-1); //即下一季度第1天减1秒
}

/// <summary>
/// 转换成中文形式的时间间隔“xx天xx时xx分xx秒”
/// </summary>
/// <param name="ts">时间间隔</param>
/// <param name="showSeconds">是否显示秒</param>
/// <returns>返回中文形式的时间间隔</returns>
public static string GetChineseTimeSpan(TimeSpan ts, bool showSeconds)
{
int days, hours, minutes, seconds;
StringBuilder sbTs = new StringBuilder();
if (ts.Ticks == 0)
{
days = 0;
hours = 0;
minutes = 0;
seconds = 0;
}
else
{
//如果时间间隔为负，将其转成正数
if (ts.Ticks < 0)
{
sbTs.Append("-");
ts = ts.Negate();
}
//计算天、小时、分钟和秒
days = ts.Days;
if (days != 0)
ts = ts.Subtract(new TimeSpan(days, 0, 0, 0));
hours = ts.Hours;
if (hours != 0)
ts = ts.Subtract(new TimeSpan(0, hours, 0, 0));
minutes = ts.Minutes;
if (minutes != 0)
ts = ts.Subtract(new TimeSpan(0, 0, minutes, 0));
seconds = ts.Seconds;
}
sbTs.AppendFormat("{0}天{1}时{2}分{3}", days, hours, minutes, showSeconds ? (seconds.ToString() + "秒") : "");
return sbTs.ToString();
}

/// <summary>
/// 获取日期所在年的周数
/// </summary>
/// <param name="dt"></param>
/// <returns></returns>
public static int GetWeekOfYear(DateTime dt)
{
DateTime yearD = new DateTime(dt.Year, 1, 1);
int diff = Convert.ToInt32(yearD.DayOfWeek);
int dayOfYear = dt.DayOfYear + diff;
return (int)(Math.Ceiling(dayOfYear / 7.0));
}
}