Timer.Elapsed 事件

定義

命名空間:

System.Timers

組件:

System.ComponentModel.TypeConverter.dll

來源:

Timer.cs

發生於間隔耗盡時。

public:
 event System::Timers::ElapsedEventHandler ^ Elapsed;

public event System.Timers.ElapsedEventHandler Elapsed;

member this.Elapsed : System.Timers.ElapsedEventHandler 

Public Custom Event Elapsed As ElapsedEventHandler 

事件類型

ElapsedEventHandler

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 Enabled 為 true ，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 Elapsed 在 ThreadPool 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。

另請參閱

• Interval
• AutoReset
• Elapsed
• ElapsedEventArgs
• ElapsedEventHandler
• Enabled