我要复职，因为今天我必须找到一种方法，不仅排除周六和周日工作日，还排除假日。更具体地说，我需要处理各种可能的假期，包括：
- 国家/地区不变的假期（至少对于西方国家而言，例如01月1日）。
- 计算出的假期（例如复活节和复活节星期一）。
- 特定国家/地区的假期（例如意大利解放日或美国ID4）。
- 特定于城镇的假期（例如罗马圣守护神日）。
- 任何其他定制的假期（例如“明天我们的办公室将关闭”）。
最终，我得出了以下一组帮助程序/扩展类：尽管它们并不是很优雅，但由于它们确实大量使用了无效循环，因此它们足以解决我的问题。我将整个源代码放在这里，希望对其他人也有用。
源代码
/// <summary>
/// Helper/extension class for manipulating date and time values.
/// </summary>
public static class DateTimeExtensions
{
/// <summary>
/// Calculates the absolute year difference between two dates.
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <returns>A whole number representing the number of full years between the specified dates.</returns>
public static int Years(DateTime dt1,DateTime dt2)
{
return Months(dt1,dt2)/12;
//if (dt2<dt1)
//{
// DateTime dt0=dt1;
// dt1=dt2;
// dt2=dt0;
//}
//int diff=dt2.Year-dt1.Year;
//int m1=dt1.Month;
//int m2=dt2.Month;
//if (m2>m1) return diff;
//if (m2==m1 && dt2.Day>=dt1.Day) return diff;
//return (diff-1);
}
/// <summary>
/// Calculates the absolute year difference between two dates.
/// Alternative, stand-alone version (without other DateTimeUtil dependency nesting required)
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <returns></returns>
public static int Years2(DateTime start, DateTime end)
{
return (end.Year - start.Year - 1) +
(((end.Month > start.Month) ||
((end.Month == start.Month) && (end.Day >= start.Day))) ? 1 : 0);
}
/// <summary>
/// Calculates the absolute month difference between two dates.
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <returns>A whole number representing the number of full months between the specified dates.</returns>
public static int Months(DateTime dt1,DateTime dt2)
{
if (dt2<dt1)
{
DateTime dt0=dt1;
dt1=dt2;
dt2=dt0;
}
dt2=dt2.AddDays(-(dt1.Day-1));
return (dt2.Year-dt1.Year)*12+(dt2.Month-dt1.Month);
}
/// <summary>
/// Returns the higher of the two date time values.
/// </summary>
/// <param name="dt1">The first of the two <c>DateTime</c> values to compare.</param>
/// <param name="dt2">The second of the two <c>DateTime</c> values to compare.</param>
/// <returns><c>dt1</c> or <c>dt2</c>, whichever is higher.</returns>
public static DateTime Max(DateTime dt1,DateTime dt2)
{
return (dt2>dt1?dt2:dt1);
}
/// <summary>
/// Returns the lower of the two date time values.
/// </summary>
/// <param name="dt1">The first of the two <c>DateTime</c> values to compare.</param>
/// <param name="dt2">The second of the two <c>DateTime</c> values to compare.</param>
/// <returns><c>dt1</c> or <c>dt2</c>, whichever is lower.</returns>
public static DateTime Min(DateTime dt1,DateTime dt2)
{
return (dt2<dt1?dt2:dt1);
}
/// <summary>
/// Adds the given number of business days to the <see cref="DateTime"/>.
/// </summary>
/// <param name="current">The date to be changed.</param>
/// <param name="days">Number of business days to be added.</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns>A <see cref="DateTime"/> increased by a given number of business days.</returns>
public static DateTime AddBusinessDays(
this DateTime current,
int days,
IEnumerable<DateTime> holidays = null)
{
var sign = Math.Sign(days);
var unsignedDays = Math.Abs(days);
for (var i = 0; i < unsignedDays; i++)
{
do
{
current = current.AddDays(sign);
}
while (current.DayOfWeek == DayOfWeek.Saturday
|| current.DayOfWeek == DayOfWeek.Sunday
|| (holidays != null && holidays.Contains(current.Date))
);
}
return current;
}
/// <summary>
/// Subtracts the given number of business days to the <see cref="DateTime"/>.
/// </summary>
/// <param name="current">The date to be changed.</param>
/// <param name="days">Number of business days to be subtracted.</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns>A <see cref="DateTime"/> increased by a given number of business days.</returns>
public static DateTime SubtractBusinessDays(
this DateTime current,
int days,
IEnumerable<DateTime> holidays)
{
return AddBusinessDays(current, -days, holidays);
}
/// <summary>
/// Retrieves the number of business days from two dates
/// </summary>
/// <param name="startDate">The inclusive start date</param>
/// <param name="endDate">The inclusive end date</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns></returns>
public static int GetBusinessDays(
this DateTime startDate,
DateTime endDate,
IEnumerable<DateTime> holidays)
{
if (startDate > endDate)
throw new NotSupportedException("ERROR: [startDate] cannot be greater than [endDate].");
int cnt = 0;
for (var current = startDate; current < endDate; current = current.AddDays(1))
{
if (current.DayOfWeek == DayOfWeek.Saturday
|| current.DayOfWeek == DayOfWeek.Sunday
|| (holidays != null && holidays.Contains(current.Date))
)
{
// skip holiday
}
else cnt++;
}
return cnt;
}
/// <summary>
/// Calculate Easter Sunday for any given year.
/// src.: https://stackoverflow.com/a/2510411/1233379
/// </summary>
/// <param name="year">The year to calcolate Easter against.</param>
/// <returns>a DateTime object containing the Easter month and day for the given year</returns>
public static DateTime GetEasterSunday(int year)
{
int day = 0;
int month = 0;
int g = year % 19;
int c = year / 100;
int h = (c - (int)(c / 4) - (int)((8 * c + 13) / 25) + 19 * g + 15) % 30;
int i = h - (int)(h / 28) * (1 - (int)(h / 28) * (int)(29 / (h + 1)) * (int)((21 - g) / 11));
day = i - ((year + (int)(year / 4) + i + 2 - c + (int)(c / 4)) % 7) + 28;
month = 3;
if (day > 31)
{
month++;
day -= 31;
}
return new DateTime(year, month, day);
}
/// <summary>
/// Retrieve holidays for given years
/// </summary>
/// <param name="years">an array of years to retrieve the holidays</param>
/// <param name="countryCode">a country two letter ISO (ex.: "IT") to add the holidays specific for that country</param>
/// <param name="cityName">a city name to add the holidays specific for that city</param>
/// <returns></returns>
public static IEnumerable<DateTime> GetHolidays(IEnumerable<int> years, string countryCode = null, string cityName = null)
{
var lst = new List<DateTime>();
foreach (var year in years.Distinct())
{
lst.AddRange(new[] {
new DateTime(year, 1, 1), // 1 gennaio (capodanno)
new DateTime(year, 1, 6), // 6 gennaio (epifania)
new DateTime(year, 5, 1), // 1 maggio (lavoro)
new DateTime(year, 8, 15), // 15 agosto (ferragosto)
new DateTime(year, 11, 1), // 1 novembre (ognissanti)
new DateTime(year, 12, 8), // 8 dicembre (immacolata concezione)
new DateTime(year, 12, 25), // 25 dicembre (natale)
new DateTime(year, 12, 26) // 26 dicembre (s. stefano)
});
// add easter sunday (pasqua) and monday (pasquetta)
var easterDate = GetEasterSunday(year);
lst.Add(easterDate);
lst.Add(easterDate.AddDays(1));
// country-specific holidays
if (!String.IsNullOrEmpty(countryCode))
{
switch (countryCode.ToUpper())
{
case "IT":
lst.Add(new DateTime(year, 4, 25)); // 25 aprile (liberazione)
break;
case "US":
lst.Add(new DateTime(year, 7, 4)); // 4 luglio (Independence Day)
break;
// todo: add other countries
case default:
// unsupported country: do nothing
break;
}
}
// city-specific holidays
if (!String.IsNullOrEmpty(cityName))
{
switch (cityName)
{
case "Rome":
case "Roma":
lst.Add(new DateTime(year, 6, 29)); // 29 giugno (s. pietro e paolo)
break;
case "Milano":
case "Milan":
lst.Add(new DateTime(year, 12, 7)); // 7 dicembre (s. ambrogio)
break;
// todo: add other cities
default:
// unsupported city: do nothing
break;
}
}
}
return lst;
}
}
使用信息
该代码是不言自明的，但是这里有几个示例来说明如何使用它。
添加10个工作日（仅跳过周六和周日）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10);
添加10个工作日（跳过2019年的星期六，星期日和所有国家/地区不变的假日）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019));
增加10个工作日（跳过2019年的星期六，星期日和所有意大利假日）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019, "IT"));
添加10个工作日（跳过2019年的星期六，星期日，所有意大利假日和罗马特定假日）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019, "IT", "Rome"));
我的博客的这篇帖子进一步解释了上述功能和代码示例。