C# 创建后台计时器以异步运行
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Creating a background timer to run asynchronously
提问by Mike Baxter
I'm really struggling with this. I'm creating a winformsapplication in visual studio and need a background timer that ticks once every half hour - the purpose of this is to pull down updates from a server.
我真的很挣扎。我正在winformsVisual Studio 中创建一个应用程序，需要一个每半小时滴答一次的后台计时器 - 这样做的目的是从服务器拉下更新。
I have tried a couple of different approaches but they have failed, either due to poor tutorial/examples, or to my own shortcomings in C#. I think it would be a waste of time to show you what I have tried so far as it seems what I tried was pretty far off the mark.
我尝试了几种不同的方法，但它们都失败了，要么是由于教程/示例不佳，要么是我自己在C#. 我认为向您展示我所尝试的内容是浪费时间，因为我尝试的内容似乎离目标很远。
Does anyone know of a clear and simple way of implementing an asynchronous background timer that is easily understandable by a C#newbie?
有谁知道实现一个C#新手很容易理解的异步后台计时器的清晰而简单的方法吗？
采纳答案by Mitch Wheat
// Create a 30 min timer
timer = new System.Timers.Timer(1800000);
// Hook up the Elapsed event for the timer.
timer.Elapsed += OnTimedEvent;
timer.Enabled = true;
...
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
// do stuff
}
with the usual caveats of: timer won't be hugely accurate and might need to GC.KeepAlive(timer)
与通常的警告：计时器不会非常准确，可能需要 GC.KeepAlive(timer)
See also: Why does a System.Timers.Timer survive GC but not System.Threading.Timer?
另请参阅：为什么 System.Timers.Timer 在 GC 中存活，而 System.Threading.Timer 不能存活？
回答by JSJ
I think you need to know about all timer classes. See Jon's answer below.
我认为您需要了解所有计时器课程。请参阅下面乔恩的回答。
What kind of timer are you using?
- System.Windows.Forms.Timer will execute in the UI thread
- System.Timers.Timer executes in a thread-pool thread unless you specify a SynchronizingObject
- System.Threading.Timer executes its callback in a thread-pool thread
In all cases, the timer itself will be asynchronous - it won't "take up" a thread until it fires.
你用的是什么定时器？
- System.Windows.Forms.Timer 将在 UI 线程中执行
- System.Timers.Timer 在线程池线程中执行，除非您指定 SynchronizingObject
- System.Threading.Timer 在线程池线程中执行其回调
在所有情况下，计时器本身都是异步的——它不会“占用”一个线程，直到它被触发。
回答by the_virt
Declare member variable in your form:
在表单中声明成员变量：
System.Timers.Timer theTimer;
On form load (or whatever other time you need to start update polling), do:
在表单加载时（或任何其他需要开始更新轮询的时间），请执行以下操作：
theTimer = new System.Timers.Timer(1800000);
theTimer.Elapsed += PollUpdates;
theTimer.Start();
Declare your PollUpdates member function like this:
像这样声明你的 PollUpdates 成员函数：
private void PollUpdates(object sender, EventArgs e)
{
}
