我正在使用一个计时器来周期性地运行一个事件（间隔为2分钟），这个已经正常工作。但是我希望在计时器创建时立即触发事件，而不是等待2分钟。
请注意，我不能通过调用方法来实现这一点，因为它需要一些时间才能运行，并且会阻塞应用程序。我需要计时器像平常一样触发并在单独的线程中运行事件。
目前我能想到的最好的方法是子类化计时器并创建一个TriggerManually方法，该方法会执行以下操作：
这将立即触发过去的事件，然后我可以将所有设置恢复为正常状态。
虽然这似乎有点绕，但有更好的方法吗？
你不能直接手动调用计时器的已过时间事件吗？
即使你期望它在线程池线程上执行，你仍然可以调用它。
class Blah
{
private Timer mTimer;
public Blah()
{
mTimer = new Timer(120000);
ElapsedEventHandler handler = new ElapsedEventHandler(Timer_Elapsed);
mTimer.Elapsed += handler;
mTimer.Enabled = true;
//Manually execute the event handler on a threadpool thread.
handler.BeginInvoke(this, null, new AsyncCallback(Timer_ElapsedCallback), handler);
}
private static void Timer_Elapsed(object source, ElapsedEventArgs e)
{
//Do stuff...
}
private void Timer_ElapsedCallback(IAsyncResult result)
{
ElapsedEventHandler handler = result.AsyncState as ElapsedEventHandler;
if (handler != null)
{
handler.EndInvoke(result);
}
}
}
EagerTimer类，它是System.Timers.Timer的子类，并添加了此功能。（这些提示来自这些文章）System.Threading.Timer，但这个类对于我的应用程序来说更简单并且运作良好。
EagerTimer
/// <summary>
// EagerTimer is a simple wrapper around System.Timers.Timer that
// provides "set up and immediately execute" functionality by adding a
// new AutoStart property, and also provides the ability to manually
// raise the Elapsed event with RaiseElapsed.
/// </summary>
public class EagerTimer : Timer
{
public EagerTimer()
: base() { }
public EagerTimer(double interval)
: base(interval) { }
// Need to hide this so we can use Elapsed.Invoke below
// (otherwise the compiler complains)
private event ElapsedEventHandler _elapsedHandler;
public new event ElapsedEventHandler Elapsed
{
add { _elapsedHandler += value; base.Elapsed += value; }
remove { _elapsedHandler -= value; base.Elapsed -= value; }
}
public new void Start()
{
// If AutoStart is enabled, we need to invoke the timer event manually
if (AutoStart)
{
this._elapsedHandler.BeginInvoke(this, null, new AsyncCallback(AutoStartCallback), _elapsedHandler); // fire immediately
}
// Proceed as normal
base.Start();
}
private void AutoStartCallback(IAsyncResult result)
{
ElapsedEventHandler handler = result.AsyncState as ElapsedEventHandler;
if (handler != null) handler.EndInvoke(result);
}
// Summary:
// Gets or sets a value indicating whether the EagerTimer should raise
// the System.Timers.Timer.Elapsed event immediately when Start() is called,
// or only after the first time it elapses. If AutoStart is false, EagerTimer behaves
// identically to System.Timers.Timer.
//
// Returns:
// true if the EagerTimer should raise the System.Timers.Timer.Elapsed
// event immediately when Start() is called; false if it should raise the System.Timers.Timer.Elapsed
// event only after the first time the interval elapses. The default is true.
[Category("Behavior")]
[DefaultValue(true)]
[TimersDescription("TimerAutoStart")]
public bool AutoStart { get; set; }
/// <summary>
/// Manually raises the Elapsed event of the System.Timers.Timer.
/// </summary>
public void RaiseElapsed()
{
if (_elapsedHandler != null)
_elapsedHandler(this, null);
}
}
单元测试
[TestClass]
public class Objects_EagerTimer_Tests
{
private const int TimerInterval = 10; // ms
private List<DateTime> _timerFires = new List<DateTime>();
private DateTime _testStart;
[TestInitialize]
public void TestSetup()
{
_timerFires.Clear();
_testStart = DateTime.Now;
}
[TestMethod]
public void Objects_EagerTimer_WithAutoStartDisabled()
{
// EagerTimer should behave as a normal System.Timers.Timer object
var timer = new EagerTimer(TimerInterval);
timer.AutoReset = false;
timer.Elapsed += timerElapsed;
timer.Start();
// Wait (not enough time for first interval)
Thread.Sleep(5);
Assert.IsFalse(_timerFires.Any());
// Wait a little longer
Thread.Sleep(TimerInterval);
Assert.AreEqual(1, _timerFires.Count);
}
[TestMethod]
public void Objects_EagerTimer_WithAutoStartEnabled()
{
// EagerTimer should fire immediately on Start()
var timer = new EagerTimer(TimerInterval);
timer.AutoReset = false;
timer.AutoStart = true;
timer.Elapsed += timerElapsed;
timer.Start();
// Wait (not enough time for first interval)
Thread.Sleep(5);
Assert.IsTrue(_timerFires.Any());
// Wait a little longer, now it will have fired twice
Thread.Sleep(TimerInterval);
Assert.AreEqual(2, _timerFires.Count);
}
[TestMethod]
public void Objects_EagerTimer_WhenRaisingManually()
{
// EagerTimer should fire immediately on Start()
var timer = new EagerTimer(TimerInterval);
timer.AutoReset = false;
timer.AutoStart = false;
timer.Elapsed += timerElapsed;
Assert.IsFalse(_timerFires.Any());
timer.RaiseElapsed();
Assert.IsTrue(_timerFires.Any());
}
private void timerElapsed(object sender, ElapsedEventArgs e) {
_timerFires.Add(DateTime.Now);
}
}
您可以考虑使用System.Threading.Timer代替吗？ 它有一个构造函数，允许您选择间隔以及延迟（可以设置为0以立即开始）。 http://msdn.microsoft.com/en-us/library/2x96zfy7.aspx
System.Threading.Timer回调中未处理的异常会导致您的应用程序崩溃。 - ivan_pozdeev
public void Start(bool withAutoStart) { if (withAutoStart) { AutoStart = true; } Start(); }- Jez