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Timer.Elapsed 事件

定義

發生於間隔耗盡時。

public:
 event System::Timers::ElapsedEventHandler ^ Elapsed;
public event System.Timers.ElapsedEventHandler Elapsed;
[System.Timers.TimersDescription("TimerIntervalElapsed")]
public event System.Timers.ElapsedEventHandler Elapsed;
member this.Elapsed : System.Timers.ElapsedEventHandler 
[<System.Timers.TimersDescription("TimerIntervalElapsed")>]
member this.Elapsed : System.Timers.ElapsedEventHandler 
Public Custom Event Elapsed As ElapsedEventHandler 

事件類型

屬性

範例

下列範例會具現化 Timer 物件,每隔兩秒 (2000 毫秒) 引發其 Timer.Elapsed 事件、設定事件的事件處理常式,然後啟動計時器。 事件處理常式會在每次引發時顯示 屬性的值 ElapsedEventArgs.SignalTime

using namespace System;
using namespace System::Timers;

public ref class Example
{
private:
    static System::Timers::Timer^ aTimer;

public:
    static void Demo()
    {
        // Create a timer and set a two second interval.
        aTimer = gcnew System::Timers::Timer();
        aTimer->Interval = 2000;

        // Hook up the Elapsed event for the timer. 
        aTimer->Elapsed += gcnew System::Timers::ElapsedEventHandler(Example::OnTimedEvent);

        // Have the timer fire repeated events (true is the default)
        aTimer->AutoReset = true;

        // Start the timer
        aTimer->Enabled = true;

        Console::WriteLine("Press the Enter key to exit the program at any time... ");
        Console::ReadLine();
    }

private:
    static void OnTimedEvent(Object^ source, System::Timers::ElapsedEventArgs^ e)
    {
        Console::WriteLine("The Elapsed event was raised at {0}", e->SignalTime);
    }
};

int main()
{
    Example::Demo();
}
// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM
using System;
using System.Timers;

public class Example
{
    private static Timer aTimer;

    public static void Main()
    {
        // Create a timer and set a two second interval.
        aTimer = new System.Timers.Timer();
        aTimer.Interval = 2000;

        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;

        // Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = true;

        // Start the timer
        aTimer.Enabled = true;

        Console.WriteLine("Press the Enter key to exit the program at any time... ");
        Console.ReadLine();
    }

    private static void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
    }
}
// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM
open System.Timers

let onTimedEvent source (e: ElapsedEventArgs) =
    printfn $"The Elapsed event was raised at {e.SignalTime}"

// Create a timer and set a two second interval.
let aTimer = new Timer()
aTimer.Interval <- 2000

// Hook up the Elapsed event for the timer. 
aTimer.Elapsed.AddHandler onTimedEvent

// Have the timer fire repeated events (true is the default)
aTimer.AutoReset <- true

// Start the timer
aTimer.Enabled <- true

printfn "Press the Enter key to exit the program at any time... "
stdin.ReadLine() |> ignore

// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM
Imports System.Timers

Public Module Example
    Private aTimer As Timer

    Public Sub Main()
        ' Create a timer and set a two second interval.
        aTimer = New System.Timers.Timer()
        aTimer.Interval = 2000

        ' Hook up the Elapsed event for the timer.  
        AddHandler aTimer.Elapsed, AddressOf OnTimedEvent

        ' Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = True

        ' Start the timer
        aTimer.Enabled = True

        Console.WriteLine("Press the Enter key to exit the program at any time... ")
        Console.ReadLine()
    End Sub

    Private Sub OnTimedEvent(source As Object, e As System.Timers.ElapsedEventArgs)
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime)
    End Sub
End Module
' The example displays output like the following: 
'       Press the Enter key to exit the program at any time... 
'       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
'       The Elapsed event was raised at 5/20/2015 8:49:06 PM

備註

Elapsed如果 Enabled 屬性為 true ,且屬性所 Interval 定義的時間間隔 (以毫秒為單位,則會引發事件) 。 AutoReset如果 屬性為 true ,則會以 屬性定義的 Interval 間隔重複引發事件;否則,只會在第一次耗用值時 Interval 引發事件一次。

如果在 Interval 啟動之後 Timer 設定 ,則會重設計數。 例如,如果您將間隔設定為 5 秒,然後將 設定 Enabledtrue ,則會在設定時間 Enabled 開始計數。 如果您在計數為 3 秒時將間隔重設為 10 秒,則會 Elapsed 在 設定為 之後 Enabledtrue 的第一次 13 秒引發事件。

SynchronizingObject如果 屬性為 null ,則會 ElapsedThreadPool 執行緒上引發 事件。 如果事件的處理 Elapsed 時間超過 Interval ,則事件可能會在另一個 ThreadPool 執行緒上再次引發。 在此情況下,事件處理常式應該重新進入。

注意

事件處理方法可能會在另一個執行緒呼叫 Stop 方法,或將 Enabled 屬性設定為 false 時,于一個執行緒上執行。 這可能會導致 Elapsed 在計時器停止之後引發事件。 方法的 Stop 範例程式碼示範一種方式,以避免這種競爭狀況。

即使 不是 ,事件也可能發生在 呼叫 或 Stop 方法之後 Dispose ,或 屬性設定為 false 之後 Enabled ,因為引發 Elapsed 事件的訊號一律排入佇列,以線上程集區執行緒上執行。 ElapsednullSynchronizingObject 解決此競爭條件的其中一種方法是設定旗標,告知事件的事件處理常式 Elapsed 忽略後續事件。

元件 Timer 會攔截並隱藏事件事件處理常式 Elapsed 擲回的所有例外狀況。 未來版本的.NET Framework可能會變更此行為。

適用於

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