Timer 類別

定義

public ref class Timer : System::ComponentModel::Component, System::ComponentModel::ISupportInitialize

public class Timer : System.ComponentModel.Component, System.ComponentModel.ISupportInitialize

type Timer = class
    inherit Component
    interface ISupportInitialize

Public Class Timer
Inherits Component
Implements ISupportInitialize

繼承

Object

MarshalByRefObject

Component

Timer

實作

ISupportInitialize

範例

下列範例會具現化 System.Timers.Timer 每兩秒引發其 Timer.Elapsed 事件的 物件， (2，000 毫秒) 、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屬性時顯示其值 ElapsedEventArgs.SignalTime 。

using System;
using System.Timers;

public class Example
{
   private static System.Timers.Timer aTimer;
   
   public static void Main()
   {
      SetTimer();

      Console.WriteLine("\nPress the Enter key to exit the application...\n");
      Console.WriteLine("The application started at {0:HH:mm:ss.fff}", DateTime.Now);
      Console.ReadLine();
      aTimer.Stop();
      aTimer.Dispose();
      
      Console.WriteLine("Terminating the application...");
   }

   private static void SetTimer()
   {
        // Create a timer with a two second interval.
        aTimer = new System.Timers.Timer(2000);
        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;
        aTimer.AutoReset = true;
        aTimer.Enabled = true;
    }

    private static void OnTimedEvent(Object source, ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
                          e.SignalTime);
    }
}
// The example displays output like the following:
//       Press the Enter key to exit the application...
//
//       The application started at 09:40:29.068
//       The Elapsed event was raised at 09:40:31.084
//       The Elapsed event was raised at 09:40:33.100
//       The Elapsed event was raised at 09:40:35.100
//       The Elapsed event was raised at 09:40:37.116
//       The Elapsed event was raised at 09:40:39.116
//       The Elapsed event was raised at 09:40:41.117
//       The Elapsed event was raised at 09:40:43.132
//       The Elapsed event was raised at 09:40:45.133
//       The Elapsed event was raised at 09:40:47.148
//
//       Terminating the application...

open System
open System.Timers

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

// Create a timer with a two second interval.
let aTimer = new Timer 2000
// Hook up the Elapsed event for the timer. 
aTimer.Elapsed.AddHandler onTimedEvent
aTimer.AutoReset <- true
aTimer.Enabled <- true

printfn "\nPress the Enter key to exit the application...\n"
printfn $"""The application started at {DateTime.Now.ToString "HH:mm:ss.fff"}"""
stdin.ReadLine() |> ignore
aTimer.Stop()
aTimer.Dispose()

printfn "Terminating the application..."

// The example displays output like the following:
//       Press the Enter key to exit the application...
//
//       The application started at 09:40:29.068
//       The Elapsed event was raised at 09:40:31.084
//       The Elapsed event was raised at 09:40:33.100
//       The Elapsed event was raised at 09:40:35.100
//       The Elapsed event was raised at 09:40:37.116
//       The Elapsed event was raised at 09:40:39.116
//       The Elapsed event was raised at 09:40:41.117
//       The Elapsed event was raised at 09:40:43.132
//       The Elapsed event was raised at 09:40:45.133
//       The Elapsed event was raised at 09:40:47.148
//
//       Terminating the application...

Imports System.Timers

Public Module Example
    Private aTimer As System.Timers.Timer

    Public Sub Main()
        SetTimer()

      Console.WriteLine("{0}Press the Enter key to exit the application...{0}",
                        vbCrLf)
      Console.WriteLine("The application started at {0:HH:mm:ss.fff}",
                        DateTime.Now)
      Console.ReadLine()
      aTimer.Stop()
      aTimer.Dispose()

      Console.WriteLine("Terminating the application...")
    End Sub

    Private Sub SetTimer()
        ' Create a timer with a two second interval.
        aTimer = New System.Timers.Timer(2000)
        ' Hook up the Elapsed event for the timer. 
        AddHandler aTimer.Elapsed, AddressOf OnTimedEvent
        aTimer.AutoReset = True
        aTimer.Enabled = True
    End Sub

    ' The event handler for the Timer.Elapsed event. 
    Private Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
        Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
                          e.SignalTime)
    End Sub 
End Module
' The example displays output like the following:
'       Press the Enter key to exit the application...
'
'       The application started at 09:40:29.068
'       The Elapsed event was raised at 09:40:31.084
'       The Elapsed event was raised at 09:40:33.100
'       The Elapsed event was raised at 09:40:35.100
'       The Elapsed event was raised at 09:40:37.116
'       The Elapsed event was raised at 09:40:39.116
'       The Elapsed event was raised at 09:40:41.117
'       The Elapsed event was raised at 09:40:43.132
'       The Elapsed event was raised at 09:40:45.133
'       The Elapsed event was raised at 09:40:47.148
'
'       Terminating the application...

備註

元件 Timer 是伺服器型計時器，會在屬性中的 Interval 毫秒數經過之後，在應用程式中引發 Elapsed 事件。 您可以設定 Timer 物件，只使用 AutoReset 屬性一次或重複引發事件。 一般而言， Timer 物件會在類別層級宣告，只要需要，它就會保留在範圍內。 然後，您可以處理其 Elapsed 事件，以提供一般處理。 例如，假設您有一部重要的伺服器必須持續執行一天 24 小時，一周 7 天。 您可以建立使用 Timer 物件定期檢查伺服器的服務，並確保系統已啟動並執行。 如果系統未回應，服務可能會嘗試重新開機伺服器或通知系統管理員。

此型別代表 IDisposable 介面。 當您完成使用型別時，您應該直接或間接處置它。 若要直接處置型別，請呼叫其 try/catch 區塊中的 Dispose 方法。 若要間接處置它，請使用語言建構函式，例如 using (在 C# 中) 或 Using (在 Visual Basic 中)。 如需詳細資訊，請參閱 IDisposable 介面文章中的＜使用實作 IDisposable 的物件＞一節。

伺服器型 System.Timers.Timer 類別的設計目的是要與多執行緒環境中的背景工作執行緒搭配使用。 伺服器計時器可以線上程之間移動以處理引發 Elapsed 的事件，導致比 Windows 計時器更精確的時間引發事件。

元件 Elapsed 會 System.Timers.Timer 根據 屬性) 毫秒 Interval 的值 (引發事件。 您可以處理此事件來執行所需的處理。 例如，假設您有一個線上銷售應用程式會持續將銷售訂單張貼至資料庫。 編譯出貨指令的服務會在訂單批次上運作，而不是個別處理每個訂單。 您可以使用 Timer 來每隔 30 分鐘啟動批次處理一次。

當 設定為 時 AutoReset ， System.Timers.Timer 物件只會在第一 Interval 次經過之後引發 Elapsed 事件一次。 false 若要在 所 Interval 定義的間隔中定期引發 Elapsed 事件，請將 設定 AutoReset 為 true ，這是預設值。

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。 此行為在.NET Framework的未來版本中可能會變更。 不過請注意，這不是以非同步方式執行的事件處理常式，而且在 C#) 中包含 await 運算子 (，或 Await Visual Basic) 中的運算子 (。 這些事件處理常式中擲回的例外狀況會傳播回呼叫執行緒，如下列範例所示。 如需非同步方法擲回之例外狀況的詳細資訊，請參閱 例外狀況處理。

using System;
using System.Threading.Tasks;
using System.Timers;

class Example
{
   static void Main()
   {
      Timer timer = new Timer(1000);
      timer.Elapsed += async ( sender, e ) => await HandleTimer();
      timer.Start();
      Console.Write("Press any key to exit... ");
      Console.ReadKey();
   }

   private static Task HandleTimer()
   {
     Console.WriteLine("\nHandler not implemented..." );
     throw new NotImplementedException();
   }
}
// The example displays output like the following:
//   Press any key to exit...
//   Handler not implemented...
//   
//   Unhandled Exception: System.NotImplementedException: The method or operation is not implemented.
//      at Example.HandleTimer()
//      at Example.<<Main>b__0>d__2.MoveNext()
//   --- End of stack trace from previous location where exception was thrown ---
//      at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c__DisplayClass2.<ThrowAsync>b__5(Object state)
//      at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
//      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
//      at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
//      at System.Threading.ThreadPoolWorkQueue.Dispatch()

open System
open System.Threading.Tasks
open System.Timers

let handleTimer () =
    printfn "\nHandler not implemented..."
    raise (NotImplementedException()): Task

let timer = new Timer 1000
timer.Elapsed.AddHandler(fun sender e -> task { do! handleTimer () } |> ignore)
timer.Start()
printf "Press any key to exit... "
Console.ReadKey() |> ignore

// The example displays output like the following:
//   Press any key to exit...
//   Handler not implemented...
//
//   Unhandled Exception: System.NotImplementedException: The method or operation is not implemented.
//      at Example.HandleTimer()
//      at Example.<<Main>b__0>d__2.MoveNext()
//   --- End of stack trace from previous location where exception was thrown ---
//      at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c__DisplayClass2.<ThrowAsync>b__5(Object state)
//      at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
//      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
//      at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
//      at System.Threading.ThreadPoolWorkQueue.Dispatch()

Imports System.Threading.Tasks
Imports System.Timers

Public Module Example
   Public Sub Main()
      Dim timer As New Timer(1000)  
      AddHandler timer.Elapsed, AddressOf Example.HandleTimer     
      'timer.Elapsed = Async ( sender, e ) => await HandleTimer()
      timer.Start()
      Console.Write("Press any key to exit... ")
      Console.ReadKey()
   End Sub

   Private Async Sub HandleTimer(sender As Object, e As EventArgs)
      Await Task.Run(Sub()
                        Console.WriteLine()
                        Console.WriteLine("Handler not implemented..." )
                        Throw New NotImplementedException()
                     End Sub)   
   End Sub
End Module
' The example displays output like the following:
'   Press any key to exit...
'   Handler not implemented...
'   
'   Unhandled Exception: System.NotImplementedException: The method or operation is not implemented.
'      at Example._Lambda$__1()
'      at System.Threading.Tasks.Task.Execute()
'   --- End of stack trace from previous location where exception was thrown ---
'      at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
'      at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
'      at Example.VB$StateMachine_0_HandleTimer.MoveNext()
'   --- End of stack trace from previous location where exception was thrown ---
'      at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c__DisplayClass2.<ThrowAsync>b__5(Object state)
'      at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
'      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
'      at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
'      at System.Threading.ThreadPoolWorkQueue.Dispatch()

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。

即使 不是 ，在 呼叫 或 Stop 方法之後 Dispose ，或 屬性設定 false 為 之後 Enabled ，就會發生事件，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式是設定旗標，告知事件的事件處理常式 Elapsed 忽略後續事件。

如果您使用 System.Timers.Timer 類別搭配使用者介面元素，例如表單或控制項，而不將計時器放在該使用者介面元素上，請將包含 Timer 的表單或控制項指派給 SynchronizingObject 屬性，讓事件封送處理至使用者介面執行緒。

如需 實例 Timer 的預設屬性值清單，請參閱 建 Timer 構函式。

建構函式

屬性

方法

事件

適用於

執行緒安全性

此類型的任何公用 static 成員都是安全線程。 並非所有的執行個體成員都是安全執行緒。

另請參閱

• AutoReset
• Interval
• Elapsed
• Timer()
• Timer