如何在一周中的特定日子为每个第一/第二/第三/第四周创建重复工作？

Question

我正在寻找表达式，以通过 hangfire 在特定周数和星期几创建有效的重复 每月 工作，根据：

RecurringJob.AddOrUpdate 有两种方法可以创建 Cron 表达式（hangfire 的帮助类和自身的字符串表达式）帮助类包含每月表达式的方法，但问题是它只有天数和时间的参数，以及何时我正在寻找有效的表达我发现了以下主题：

Hangfire Cron expressions are not valid 我试图找到任何有效的方法来为我的目的创建表达式，但是当我尝试用 http://cron.schlitt.info 或 https://crontab.guru(they 解析它们时，我发现的所有表达式都失败了，例如特定周的天数范围hangfire 用来解析表达式）：

1-7 first week
8-14 second week
15-21 third week
22-28 forth week
29-31 fifth week

Answer 1

据我了解，cron 表达式不能包含周数，请参阅下面的 cron 标准：

minute (0-59)
hour (0-23)
day of the month (1-31)
month of the year (1-12)
day of the week (0-6 with 0=Sunday)

话虽如此，但在不了解您的确切情况的情况下，这里有两种可能的解决方案：

解决方案 1：

忽略周数并计算天数：

        RecurringJob.AddOrUpdate(() => Execute(), "0 6 1,2,3,4,5,6,7 * *");// Run every morning @ 6 if day between 1 and 7
        RecurringJob.AddOrUpdate(() => Execute(), "0 6 8,9,10,11,12,13,14 * *");// Run every morning @ 6 if day between 8 and 14
        RecurringJob.AddOrUpdate(() => Execute(), "0 6 15,16,17,18,19,20,21 * *");// Run every morning @ 6 if day between 15 and 21
        RecurringJob.AddOrUpdate(() => Execute(), "0 6 22,23,24,25,26,27,28 * *");// Run every morning @ 6 if day between 22 and 28
        RecurringJob.AddOrUpdate(() => Execute(), "0 6 29,30,31 * *");// Run every morning @ 6 if day between 29 and 31

解决方案 2：

也可以根据您的业务需求解决问题的伪代码：

每天 6 点运行一次的主要作业，如果适用，它将排队其他作业。

static void Main(string[] args)
    {
        RecurringJob.AddOrUpdate(() => Execute(), "0 6 * * *");// Run every morning @ 6
    }

    private static void Execute()
    {
        int currentWeekNumber = GetWeekNumberOfMonth(DateTime.Now);
        int dayNumber = (int)DateTime.Now.DayOfWeek;

        if ((currentWeekNumber == 1) && (dayNumber == (int)DayOfWeek.Wednesday))
            BackgroundJob.Enqueue(() => Console.WriteLine("Week 1 Job"));

        if ((currentWeekNumber == 2) && (dayNumber == (int)DayOfWeek.Monday))
            BackgroundJob.Enqueue(() => Console.WriteLine("Week 2 Job"));

        if ((currentWeekNumber == 3) && (dayNumber == (int)DayOfWeek.Thursday))
            BackgroundJob.Enqueue(() => Console.WriteLine("Week 3 Job"));

        if ((currentWeekNumber == 4) && (dayNumber == (int)DayOfWeek.Friday))
            BackgroundJob.Enqueue(() => Console.WriteLine("Week 4 Job"));
    }


    private static int GetWeekNumberOfMonth(DateTime date)
    {
        date = date.Date;
        DateTime firstMonthDay = new DateTime(date.Year, date.Month, 1);
        DateTime firstMonthMonday = firstMonthDay.AddDays((DayOfWeek.Monday + 7 - firstMonthDay.DayOfWeek) % 7);
        if (firstMonthMonday > date)
        {
            firstMonthDay = firstMonthDay.AddMonths(-1);
            firstMonthMonday = firstMonthDay.AddDays((DayOfWeek.Monday + 7 - firstMonthDay.DayOfWeek) % 7);
        }
        return (date - firstMonthMonday).Days / 7 + 1;
    }