BackgroundWorker.IsBusy 属性

定义

命名空间:

System.ComponentModel

程序集:

System.ComponentModel.EventBasedAsync.dll

Source:

BackgroundWorker.cs

获取一个值，指示 BackgroundWorker 是否正在运行异步操作。

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

public bool IsBusy { get; }

member this.IsBusy : bool

Public ReadOnly Property IsBusy As Boolean

属性值

Boolean

如果 BackgroundWorker 正在运行异步操作，则为 true；否则为 false。

示例

下面的代码示例演示如何使用 IsBusy 属性等待操作完成 BackgroundWorker 。 此代码示例是 如何：在后台下载文件中所述的较大示例的一部分。

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

注解

调用 RunWorkerAsync时， BackgroundWorker 将启动异步操作。

另请参阅

• RunWorkerCompleted
• EventArgs
• RunWorkerAsync
• 如何：在后台运行操作
• 如何：在后台下载文件