DoWorkEventHandler 代理人

定義

命名空間:

System.ComponentModel

組件:

netstandard.dll, System.ComponentModel.EventBasedAsync.dll

來源:

DoWorkEvent.cs

代表處理 DoWork 事件的方法。 無法繼承這個類別。

public delegate void DoWorkEventHandler(System::Object ^ sender, DoWorkEventArgs ^ e);

public delegate void DoWorkEventHandler(object? sender, DoWorkEventArgs e);

type DoWorkEventHandler = delegate of obj * DoWorkEventArgs -> unit

Public Delegate Sub DoWorkEventHandler(sender As Object, e As DoWorkEventArgs)

參數

sender

Object

事件的 來源。

e

DoWorkEventArgs

DoWorkEventArgs A 包含事件資料。

範例

以下程式碼範例示範如何使用 DoWorkEventHandler 代理來處理 DoWork 事件。 完整程式碼列表請參見 「如何：在背景執行操作」。

void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // Do not access the form's BackgroundWorker reference directly.
    // Instead, use the reference provided by the sender parameter.
    BackgroundWorker bw = sender as BackgroundWorker;

    // Extract the argument.
    int arg = (int)e.Argument;

    // Start the time-consuming operation.
    e.Result = TimeConsumingOperation(bw, arg);

    // If the operation was canceled by the user, 
    // set the DoWorkEventArgs.Cancel property to true.
    if (bw.CancellationPending)
    {
        e.Cancel = true;
    }
}

Private Sub backgroundWorker1_DoWork( _
sender As Object, e As DoWorkEventArgs) _
Handles backgroundWorker1.DoWork

   ' Do not access the form's BackgroundWorker reference directly.
   ' Instead, use the reference provided by the sender parameter.
   Dim bw As BackgroundWorker = CType( sender, BackgroundWorker )
   
   ' Extract the argument.
   Dim arg As Integer = Fix(e.Argument)
   
   ' Start the time-consuming operation.
   e.Result = TimeConsumingOperation(bw, arg)
   
   ' If the operation was canceled by the user, 
   ' set the DoWorkEventArgs.Cancel property to true.
   If bw.CancellationPending Then
      e.Cancel = True
   End If

End Sub

備註

當你建立 DoWorkEventHandler 代理人時，你就能確定處理事件的方法。 要將事件與你的事件處理器關聯，請將該代理的實例加入事件中。 事件處理方法在事件發生時會被呼叫，除非移除代理。 欲了解更多關於事件處理代表的資訊，請參閱 「處理與提升事件」。

擴充方法

名稱	Description
GetMethodInfo(Delegate)	取得一個代表指定代理所代表方法的物件。

另請參閱

• BackgroundWorker
• 如何在背景執行操作: