如何使用.NET Timer类在特定时间触发事件？ [英] How to use the .NET Timer class to trigger an event at a specific time?

问题描述

我想在我的应用程序时在一定的时间之日其连续运行触发的事件，称下午4:00。我想过运行计时器每一秒，当时间等于下午4:00运行事件。这样可行。但我不知道是否有一种方法在下午4:00到刚刚拿到回调一次，不必继续检查。

I would like to have an event triggered in my app which runs continuously during the day at a certain time, say at 4:00pm. I thought about running the timer every second and when the time is equal to 4:00pm run the event. That works. But I'm wondering if there's a way to just get the callback once at 4:00pm and not having to keep checking.

推荐答案

如何这样的事情，使用<$c$c>System.Threading.Timer上课吗？

How about something like this, using the System.Threading.Timer class?

var t = new Timer(TimerCallback);

// Figure how much time until 4:00
DateTime now = DateTime.Now;
DateTime fourOClock = DateTime.Today.AddHours(16.0);

// If it's already past 4:00, wait until 4:00 tomorrow    
if (now > fourOClock)
{
    fourOClock = fourOClock.AddDays(1.0);
}

int msUntilFour = (int)((fourOClock - now).TotalMilliseconds);

// Set the timer to elapse only once, at 4:00.
t.Change(msUntilFour, Timeout.Infinite);

请注意，如果您使用 System.Threading.Timer ，由 TimerCallback 指定的回调将被执行的一个线程池（非UI）线程，所以如果你在4:00做你的UI策划的东西，你就会有code恰当（例如，使用元帅控制.Invoke 在Windows窗体应用程序，或 Dispatcher.Invoke 在一个WPF应用程序）。

Note that if you use a System.Threading.Timer, the callback specified by TimerCallback will be executed on a thread pool (non-UI) thread—so if you're planning on doing something with your UI at 4:00, you'll have to marshal the code appropriately (e.g., using Control.Invoke in a Windows Forms app, or Dispatcher.Invoke in a WPF app).

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