如何在一天中的特定时间运行 .net Core IHosted 服务？

Question

我有以下计时器在 .Net 核心 Ihosted 服务中运行，

TimeSpan ScheduledTimespan;
string[] formats = { @"hh\:mm\:ss", "hh\\:mm" };
string strTime = Startup.Configuration["AppSettings:JobStartTime"].ToString();
var success = TimeSpan.TryParseExact(strTime, formats, CultureInfo.InvariantCulture, out ScheduledTimespan);
Timer _timer = new Timer(JobToRun, null, TimeSpan.Zero, ScheduledTimespan);

我正在使用这个特定的重载，

public Timer(TimerCallback callback, object state, TimeSpan dueTime, TimeSpan period);

但是JobToRun一旦控制到达它就会执行。如何让它在每天的特定时间运行？提前致谢。

Answer 1

使用 Cron 作业

1. 创建 ASP.NET Core Web 项目

2. 添加 NuGet 包 Microsoft.Extensions.Hosting

3. 添加 NuGet 包 Cronos

4. Crete 抽象类 CronJobService - 在这个 CronJobService 中，我们使用一个定时器来跟踪时间并在时间达到预定时间时触发后台任务

   public abstract class CronJobService : IHostedService, IDisposable
   {
     private System.Timers.Timer _timer;
     private readonly CronExpression _expression;
     private readonly TimeZoneInfo _timeZoneInfo;
   
     protected CronJobService(string cronExpression, TimeZoneInfo timeZoneInfo)
     {
       _expression = CronExpression.Parse(cronExpression);
       _timeZoneInfo = timeZoneInfo;
     }
   
     public virtual async Task StartAsync(CancellationToken cancellationToken)
     {
      await ScheduleJob(cancellationToken);
     }
   
     protected virtual async Task ScheduleJob(CancellationToken cancellationToken)
     {
        var next = _expression.GetNextOccurrence(DateTimeOffset.Now, _timeZoneInfo);
        if (next.HasValue)
        {
          var delay = next.Value - DateTimeOffset.Now;
          if (delay.TotalMilliseconds <= 0)   // prevent non-positive values from being passed into Timer
          {
             await ScheduleJob(cancellationToken);
          }
          _timer = new System.Timers.Timer(delay.TotalMilliseconds);
          _timer.Elapsed += async (sender, args) =>
          {
             _timer.Dispose();  // reset and dispose timer
             _timer = null;
   
             if (!cancellationToken.IsCancellationRequested)
             {
                 await DoWork(cancellationToken);
             }
   
             if (!cancellationToken.IsCancellationRequested)
             {
                 await ScheduleJob(cancellationToken);    // reschedule next
             }
          };
          _timer.Start();
        }
        await Task.CompletedTask;
     }
   
     public virtual async Task DoWork(CancellationToken cancellationToken)
     {
        await Task.Delay(5000, cancellationToken);  // do the work
     }
   
     public virtual async Task StopAsync(CancellationToken cancellationToken)
     {
       _timer?.Stop();
       await Task.CompletedTask;
     }
   
     public virtual void Dispose()
     {
       _timer?.Dispose();
     }
   }
   

5. 继承自 CronJobService

     public class XXXCronJob:CronJobService
     {
       private readonly ILogger<CronJob> _logger;
   
       public XXXCronJob(IScheduleConfig<CronJob > config, ILogger<CronJob> logger)
       : base(config.CronExpression, config.TimeZoneInfo)
       {
        _logger = logger;
       }
   
       public override Task StartAsync(CancellationToken cancellationToken)
       {
        _logger.LogInformation("CronJob  starts.");
        return base.StartAsync(cancellationToken);
       }
   
       public override Task DoWork(CancellationToken cancellationToken)
       {
        _logger.LogInformation($"{DateTime.Now:hh:mm:ss} CronJob  is working.");
        return Task.CompletedTask;
       }
   
       public override Task StopAsync(CancellationToken cancellationToken)
       {
        _logger.LogInformation("CronJob  is stopping.");
        return base.StopAsync(cancellationToken);
       }
    }
   

6. 添加新接口IScheduleConfig

    public interface IScheduleConfig<T>
    {
      string CronExpression { get; set; }
      TimeZoneInfo TimeZoneInfo { get; set; }
    }
   

7. 实现 IScheduleConfig

    public class ScheduleConfig<T> : IScheduleConfig<T>
    {
      public string CronExpression { get; set; }
      public TimeZoneInfo TimeZoneInfo { get; set; }
    }
   

8. 添加扩展类 ScheduledServiceExtensions

    public static class ScheduledServiceExtensions
    {
       public static IServiceCollection AddCronJob<T>(this IServiceCollection services, Action<IScheduleConfig<T>> options) where T : CronJobService
       {
          if (options == null)
          {
             throw new ArgumentNullException(nameof(options), @"Please provide Schedule Configurations.");
          }
          var config = new ScheduleConfig<T>();
          options.Invoke(config);
          if (string.IsNullOrWhiteSpace(config.CronExpression))
          {
             throw new ArgumentNullException(nameof(ScheduleConfig<T>.CronExpression), @"Empty Cron Expression is not allowed.");
          }
   
          services.AddSingleton<IScheduleConfig<T>>(config);
          services.AddHostedService<T>();
         return services;
       }
    }
   

9. 使用泛型调度多个 Cron 作业

    public void ConfigureServices(IServiceCollection services)
    {
      services.AddCronJob<XXXCronJob>(c =>
      {
        c.TimeZoneInfo = TimeZoneInfo.Local;
        c.CronExpression = @"00 05 * * *";
      });
      services.AddCronJob<YYYCronJob>(c =>
      {
        c.TimeZoneInfo = TimeZoneInfo.Local;
        c.CronExpression = @"00 08 * * *";
      });
      services.AddCronJob<ZZZCronJob>(c =>
      {
        c.TimeZoneInfo = TimeZoneInfo.Local;
        c.CronExpression = @"30 14 * * *";
      });
    }
   

   第一个是 05:00 AM。

   第二个是 08:00 AM

   最后一个是下午 14:30。

Answer 2

以下函数返回解析的作业运行时间

private static TimeSpan getScheduledParsedTime()
{
     string[] formats = { @"hh\:mm\:ss", "hh\\:mm" };
     string jobStartTime = "07:10";
     TimeSpan.TryParseExact(jobStartTime, formats, CultureInfo.InvariantCulture, out TimeSpan ScheduledTimespan);
     return ScheduledTimespan;
}

以下函数返回从当天当前时间开始的延迟时间。如果当天的当前时间超过了作业运行时间，则会在作业运行中添加适当的延迟，如下所示，

private static TimeSpan getJobRunDelay()
{
    TimeSpan scheduledParsedTime = getScheduledParsedTime();
    TimeSpan curentTimeOftheDay = TimeSpan.Parse(DateTime.Now.TimeOfDay.ToString("hh\\:mm"));
    TimeSpan delayTime = scheduledParsedTime >= curentTimeOftheDay
        ? scheduledParsedTime - curentTimeOftheDay
        : new TimeSpan(24, 0, 0) - curentTimeOftheDay + scheduledParsedTime;
    return delayTime;
}

下面的计时器将调用methodToExecute基于JobRunDelay每天

_timer = new Timer(methodToExecute, null, getJobRunDelay(), new TimeSpan(24, 0, 0));