RunWorkerCompletedEventArgs Classe

Définition

public ref class RunWorkerCompletedEventArgs : System::ComponentModel::AsyncCompletedEventArgs

public class RunWorkerCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs

type RunWorkerCompletedEventArgs = class
    inherit AsyncCompletedEventArgs

Public Class RunWorkerCompletedEventArgs
Inherits AsyncCompletedEventArgs

Héritage

Object

EventArgs

AsyncCompletedEventArgs

RunWorkerCompletedEventArgs

Exemples

L’exemple de code suivant illustre l’utilisation de RunWorkerCompletedEventArgs. Cet exemple fait partie d’un exemple plus grand pour la BackgroundWorker classe .

// This event handler deals with the results of the
// background operation.
void backgroundWorker1_RunWorkerCompleted( Object^ /*sender*/, RunWorkerCompletedEventArgs^ e )
{
   // First, handle the case where an exception was thrown.
   if ( e->Error != nullptr )
   {
      MessageBox::Show( e->Error->Message );
   }
   else
   if ( e->Cancelled )
   {
      // Next, handle the case where the user cancelled 
      // the operation.
      // Note that due to a race condition in 
      // the DoWork event handler, the Cancelled
      // flag may not have been set, even though
      // CancelAsync was called.
      resultLabel->Text = "Cancelled";
   }
   else
   {
      // Finally, handle the case where the operation 
      // succeeded.
      resultLabel->Text = e->Result->ToString();
   }

   // Enable the UpDown control.
   this->numericUpDown1->Enabled = true;

   // Enable the Start button.
   startAsyncButton->Enabled = true;

   // Disable the Cancel button.
   cancelAsyncButton->Enabled = false;
}

// This event handler deals with the results of the
// background operation.
private void backgroundWorker1_RunWorkerCompleted(
    object sender, RunWorkerCompletedEventArgs e)
{
    // First, handle the case where an exception was thrown.
    if (e.Error != null)
    {
        MessageBox.Show(e.Error.Message);
    }
    else if (e.Cancelled)
    {
        // Next, handle the case where the user canceled 
        // the operation.
        // Note that due to a race condition in 
        // the DoWork event handler, the Cancelled
        // flag may not have been set, even though
        // CancelAsync was called.
        resultLabel.Text = "Canceled";
    }
    else
    {
        // Finally, handle the case where the operation 
        // succeeded.
        resultLabel.Text = e.Result.ToString();
    }

    // Enable the UpDown control.
    this.numericUpDown1.Enabled = true;

    // Enable the Start button.
    startAsyncButton.Enabled = true;

    // Disable the Cancel button.
    cancelAsyncButton.Enabled = false;
}

' This event handler deals with the results of the
' background operation.
Private Sub backgroundWorker1_RunWorkerCompleted( _
ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) _
Handles backgroundWorker1.RunWorkerCompleted

    ' First, handle the case where an exception was thrown.
    If (e.Error IsNot Nothing) Then
        MessageBox.Show(e.Error.Message)
    ElseIf e.Cancelled Then
        ' Next, handle the case where the user canceled the 
        ' operation.
        ' Note that due to a race condition in 
        ' the DoWork event handler, the Cancelled
        ' flag may not have been set, even though
        ' CancelAsync was called.
        resultLabel.Text = "Canceled"
    Else
        ' Finally, handle the case where the operation succeeded.
        resultLabel.Text = e.Result.ToString()
    End If

    ' Enable the UpDown control.
    Me.numericUpDown1.Enabled = True

    ' Enable the Start button.
    startAsyncButton.Enabled = True

    ' Disable the Cancel button.
    cancelAsyncButton.Enabled = False
End Sub

Remarques

Lors de l’utilisation du modèle asynchrone basé sur les événements pour les opérations asynchrones, un formulaire ou un contrôle Windows Forms lance une opération asynchrone en appelant la BackgroundWorker.RunWorkerAsync méthode . La méthode à son tour déclenche l’événement BackgroundWorker.DoWork de manière asynchrone et lui passe un DoWorkEventArgs instance. Si l’opération asynchrone retourne une valeur, le BackgroundWorker.DoWork gestionnaire d’événements l’affecte généralement à la DoWorkEventArgs.Result propriété . Une fois l’opération asynchrone terminée, l’événement BackgroundWorker.RunWorkerCompleted est déclenché et reçoit une RunWorkerCompletedEventArgs instance qui contient des informations sur la status de l’opération (si elle a été annulée, défectueuse ou terminée avec succès). Si elle s’est terminée avec succès, sa Result propriété contient la valeur retournée par l’opération asynchrone et précédemment affectée à la DoWorkEventArgs.Result propriété.

Constructeurs

Propriétés

Méthodes

S’applique à

Voir aussi

• BackgroundWorker
• Procédure : exécuter une opération en arrière-plan
• Procédure : télécharger un fichier en arrière-plan