BackgroundWorker.RunWorkerAsync 方法

定義

命名空間:

System.ComponentModel

組件:

netstandard.dll, System.ComponentModel.EventBasedAsync.dll

開始執行背景操作。

多載

名稱	Description
RunWorkerAsync()	開始執行背景操作。
RunWorkerAsync(Object)	開始執行背景操作。

RunWorkerAsync()

來源:

BackgroundWorker.cs

開始執行背景操作。

public:
 void RunWorkerAsync();

public void RunWorkerAsync();

member this.RunWorkerAsync : unit -> unit

Public Sub RunWorkerAsync ()

例外狀況

InvalidOperationException

IsBusy 為 true。

範例

以下程式碼範例示範 RunWorkerAsync 使用此方法啟動非同步操作。 它是《 如何：在背景下載檔案》中描述的一個更大範例的一部分。

void downloadButton_Click(object sender, EventArgs e)
{
    // Start the download operation in the background.
    backgroundWorker1.RunWorkerAsync();

    // Disable the button for the duration of the download.
    downloadButton.Enabled = false;

    // Once you have started the background thread you
    // can exit the handler and the application will
    // wait until the RunWorkerCompleted event is raised.

    // Or if you want to do something else in the main thread,
    // such as update a progress bar, you can do so in a loop
    // while checking IsBusy to see if the background task is
    // still running.

    while (backgroundWorker1.IsBusy)
    {
        progressBar1.Increment(1);
        // Keep UI messages moving, so the form remains
        // responsive during the asynchronous operation.
        Application.DoEvents();
    }
}

Private Sub downloadButton_Click( _
    ByVal sender As Object, _
    ByVal e As EventArgs) _
    Handles downloadButton.Click

    ' Start the download operation in the background.
    Me.backgroundWorker1.RunWorkerAsync()

    ' Disable the button for the duration of the download.
    Me.downloadButton.Enabled = False

    ' Once you have started the background thread you 
    ' can exit the handler and the application will 
    ' wait until the RunWorkerCompleted event is raised.

    ' If you want to do something else in the main thread,
    ' such as update a progress bar, you can do so in a loop 
    ' while checking IsBusy to see if the background task is
    ' still running.
    While Me.backgroundWorker1.IsBusy
        progressBar1.Increment(1)
        ' Keep UI messages moving, so the form remains 
        ' responsive during the asynchronous operation.
        Application.DoEvents()
    End While
End Sub

備註

該 RunWorkerAsync 方法會提交請求以非同步方式啟動操作。 當請求被處理時， DoWork 事件會被觸發，進而開始執行背景操作。

如果背景操作已經在執行，再次呼叫 RunWorkerAsync 會產生一個 InvalidOperationException。

另請參閱

• DoWork
• 如何在背景執行操作:
• 管理執行緒最佳做法
• 在背景中下載檔案

RunWorkerAsync(Object)

來源:

BackgroundWorker.cs

開始執行背景操作。

public:
 void RunWorkerAsync(System::Object ^ argument);

public void RunWorkerAsync(object? argument);

member this.RunWorkerAsync : obj -> unit

Public Sub RunWorkerAsync (argument As Object)

參數

argument

Object

一個參數，供背景操作在事件處理程序 DoWork 中執行。

例外狀況

InvalidOperationException

IsBusy 為 true。

範例

以下程式碼範例示範 RunWorkerAsync 使用此方法啟動非同步操作。 此程式碼範例是本類別更大範例 BackgroundWorker 的一部分。

// Start the asynchronous operation.
backgroundWorker1->RunWorkerAsync( numberToCompute );

// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync(numberToCompute);

' Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync(numberToCompute)

備註

該 RunWorkerAsync 方法會提交請求以非同步方式啟動操作。 當請求被處理時， DoWork 事件會被觸發，進而開始執行背景操作。

如果你的操作需要參數，你可以將它作為 argument 參數提供給 RunWorkerAsync。

如果背景操作已經在執行，再次呼叫 RunWorkerAsync 會產生一個 InvalidOperationException。

另請參閱

• DoWork
• 如何在背景執行操作:
• 在背景中下載檔案
• 管理執行緒最佳做法