DownloadDataCompletedEventArgs Classe

Définition

Espace de noms:

System.Net

Assembly:

System.Net.WebClient.dll

Source:

WebClient.cs

Fournit des données pour l'événement DownloadDataCompleted.

public ref class DownloadDataCompletedEventArgs : System::ComponentModel::AsyncCompletedEventArgs

public class DownloadDataCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs

type DownloadDataCompletedEventArgs = class
    inherit AsyncCompletedEventArgs

Public Class DownloadDataCompletedEventArgs
Inherits AsyncCompletedEventArgs

Héritage

Object

EventArgs

AsyncCompletedEventArgs

DownloadDataCompletedEventArgs

Exemples

L’exemple de code suivant illustre le téléchargement d’une ressource spécifiée par l’utilisateur.

// Sample call : DownLoadDataInBackground ("http://www.contoso.com/GameScores.html");
void DownloadDataInBackground( String^ address )
{
   System::Threading::AutoResetEvent^ waiter = gcnew System::Threading::AutoResetEvent( false );
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);

   // Specify that the DownloadDataCallback method gets called
   // when the download completes.
   client->DownloadDataCompleted += gcnew DownloadDataCompletedEventHandler( DownloadDataCallback );
   client->DownloadDataAsync( uri, waiter );

   // Block the main application thread. Real applications
   // can perform other tasks while waiting for the download to complete.
   waiter->WaitOne();
}

// Sample call : DownLoadDataInBackground ("http://www.contoso.com/GameScores.html");
public static void DownloadDataInBackground(string address)
{
    System.Threading.AutoResetEvent waiter = new System.Threading.AutoResetEvent(false);
    WebClient client = new WebClient();
    Uri uri = new Uri(address);

    // Specify that the DownloadDataCallback method gets called
    // when the download completes.
    client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(DownloadDataCallback);
    client.DownloadDataAsync(uri, waiter);

    // Block the main application thread. Real applications
    // can perform other tasks while waiting for the download to complete.
    waiter.WaitOne();
}

'  Sample call : DownLoadDataInBackground ("http:' www.contoso.com/GameScores.html")
Public Shared Sub DownloadDataInBackground(ByVal address As String)

    Dim waiter As System.Threading.AutoResetEvent = New System.Threading.AutoResetEvent(False)
    Dim client As WebClient = New WebClient()

    '  Specify that the DownloadDataCallback method gets called
    '  when the download completes.
    AddHandler client.DownloadDataCompleted, AddressOf DownloadDataCallback
                Dim uri as Uri = New Uri(address)
    client.DownloadDataAsync(uri, waiter)

    '  Block the main application thread. Real applications
    '  can perform other tasks while waiting for the download to complete.
    waiter.WaitOne()
End Sub

La méthode suivante est appelée une fois le téléchargement terminé.

void DownloadDataCallback( Object^ /*sender*/, DownloadDataCompletedEventArgs^ e )
{
   System::Threading::AutoResetEvent^ waiter = dynamic_cast<System::Threading::AutoResetEvent^>(e->UserState);
   try
   {

      // If the request was not canceled and did not throw
      // an exception, display the resource.
      if (  !e->Cancelled && e->Error == nullptr )
      {
         array<Byte>^data = dynamic_cast<array<Byte>^>(e->Result);
         String^ textData = System::Text::Encoding::UTF8->GetString( data );
         Console::WriteLine( textData );
      }
   }
   finally
   {

      // Let the main application thread resume.
      waiter->Set();
   }

}

private static void DownloadDataCallback(Object sender, DownloadDataCompletedEventArgs e)
{
    System.Threading.AutoResetEvent waiter = (System.Threading.AutoResetEvent)e.UserState;

    try
    {
        // If the request was not canceled and did not throw
        // an exception, display the resource.
        if (!e.Cancelled && e.Error == null)
        {
            byte[] data = (byte[])e.Result;
            string textData = System.Text.Encoding.UTF8.GetString(data);

            Console.WriteLine(textData);
        }
    }
    finally
    {
        // Let the main application thread resume.
        waiter.Set();
    }
}

Private Shared Sub DownloadDataCallback(ByVal sender As Object, ByVal e As DownloadDataCompletedEventArgs)

    Dim waiter As System.Threading.AutoResetEvent = CType(e.UserState, System.Threading.AutoResetEvent)

    Try

        '  If the request was not canceled and did not throw
        '  an exception, display the resource.
        If e.Cancelled = False AndAlso e.Error Is Nothing Then

            Dim data() As Byte = CType(e.Result, Byte())
            Dim textData As String = System.Text.Encoding.UTF8.GetString(data)

            Console.WriteLine(textData)
        End If
    Finally

        '  Let the main application thread resume.
        waiter.Set()
    End Try
End Sub

Remarques

Les instances de cette classe sont passées à .DownloadDataCompletedEventHandler

Propriétés

Cancelled	Obtient une valeur qui indique si une opération asynchrone a été annulée. (Hérité de AsyncCompletedEventArgs)
Error	Obtient une valeur qui indique quelle erreur s'est produite pendant une opération asynchrone. (Hérité de AsyncCompletedEventArgs)
Result	Obtient les données qui sont téléchargées par une méthode DownloadDataAsync.
UserState	Obtient l'identificateur unique de la tâche asynchrone. (Hérité de AsyncCompletedEventArgs)

Méthodes

Equals(Object)	Détermine si l'objet spécifié est égal à l'objet actuel. (Hérité de Object)
GetHashCode()	Fait office de fonction de hachage par défaut. (Hérité de Object)
GetType()	Obtient le Type de l'instance actuelle. (Hérité de Object)
MemberwiseClone()	Crée une copie superficielle du Object actuel. (Hérité de Object)
RaiseExceptionIfNecessary()	Lève une exception fournie par l'utilisateur en cas d'échec d'une opération asynchrone. (Hérité de AsyncCompletedEventArgs)
ToString()	Retourne une chaîne qui représente l'objet actuel. (Hérité de Object)