BackgroundWorker.IsBusy 屬性

定義

命名空間:

System.ComponentModel

組件:

System.ComponentModel.EventBasedAsync.dll

來源:

BackgroundWorker.cs

取得值，指出 BackgroundWorker 是否正在執行非同步作業。

public:
 property bool IsBusy { bool get(); };

public bool IsBusy { get; }

member this.IsBusy : bool

Public ReadOnly Property IsBusy As Boolean

屬性值

Boolean

如果 BackgroundWorker 正在執行非同步作業，則為 true，否則為 false。

範例

下列程式代碼範例示範如何使用 IsBusy 屬性等候作業完成 BackgroundWorker 。 此程式代碼範例是 如何：在背景下載檔案中所述較大範例的一部分。

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

    // Disable the button for the duration of the download.
    this.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 (this.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

當您呼叫 RunWorkerAsync時，會BackgroundWorker啟動異步操作。

另請參閱

• RunWorkerCompleted
• EventArgs
• RunWorkerAsync
• 作法：在背景執行作業
• 作法：在背景下載檔案