執行緒計時器 (C# 和 Visual Basic)
System.Threading.Timer 類別 (Class) 對定期在個別執行緒上執行工作而言是很有用的。 例如，您可以使用執行緒計時器來檢查狀態和資料庫的完整性，或備份重要的檔案。
執行緒計時器範例
下列範例每隔兩秒便會開啟工作，並使用旗標來初始化停止計時器的 Dispose 方法。 此範例會公佈狀態至輸出視窗。
Private Class StateObjClass
' Used to hold parameters for calls to TimerTask.
Public SomeValue As Integer
Public TimerReference As System.Threading.Timer
Public TimerCanceled As Boolean
End Class
Public Sub RunTimer()
Dim StateObj As New StateObjClass
StateObj.TimerCanceled = False
StateObj.SomeValue = 1
Dim TimerDelegate As New System.Threading.TimerCallback(AddressOf TimerTask)
' Create a timer that calls a procedure every 2 seconds.
' Note: There is no Start method; the timer starts running as soon as
' the instance is created.
Dim TimerItem As New System.Threading.Timer(TimerDelegate, StateObj,
2000, 2000)
' Save a reference for Dispose.
StateObj.TimerReference = TimerItem
' Run for ten loops.
While StateObj.SomeValue < 10
' Wait one second.
System.Threading.Thread.Sleep(1000)
End While
' Request Dispose of the timer object.
StateObj.TimerCanceled = True
End Sub
Private Sub TimerTask(ByVal StateObj As Object)
Dim State As StateObjClass = CType(StateObj, StateObjClass)
' Use the interlocked class to increment the counter variable.
System.Threading.Interlocked.Increment(State.SomeValue)
System.Diagnostics.Debug.WriteLine("Launched new thread " & Now.ToString)
If State.TimerCanceled Then
' Dispose Requested.
State.TimerReference.Dispose()
System.Diagnostics.Debug.WriteLine("Done " & Now)
End If
End Sub
private class StateObjClass
{
// Used to hold parameters for calls to TimerTask.
public int SomeValue;
public System.Threading.Timer TimerReference;
public bool TimerCanceled;
}
public void RunTimer()
{
StateObjClass StateObj = new StateObjClass();
StateObj.TimerCanceled = false;
StateObj.SomeValue = 1;
System.Threading.TimerCallback TimerDelegate =
new System.Threading.TimerCallback(TimerTask);
// Create a timer that calls a procedure every 2 seconds.
// Note: There is no Start method; the timer starts running as soon as
// the instance is created.
System.Threading.Timer TimerItem =
new System.Threading.Timer(TimerDelegate, StateObj, 2000, 2000);
// Save a reference for Dispose.
StateObj.TimerReference = TimerItem;
// Run for ten loops.
while (StateObj.SomeValue < 10)
{
// Wait one second.
System.Threading.Thread.Sleep(1000);
}
// Request Dispose of the timer object.
StateObj.TimerCanceled = true;
}
private void TimerTask(object StateObj)
{
StateObjClass State = (StateObjClass)StateObj;
// Use the interlocked class to increment the counter variable.
System.Threading.Interlocked.Increment(ref State.SomeValue);
System.Diagnostics.Debug.WriteLine("Launched new thread " + DateTime.Now.ToString());
if (State.TimerCanceled)
// Dispose Requested.
{
State.TimerReference.Dispose();
System.Diagnostics.Debug.WriteLine("Done " + DateTime.Now.ToString());
}
}
當 System.Windows.Forms.Timer 物件無法使用時 (例如在開發主控台應用程式時)，執行緒計時器便特別有用。