WebClient.DownloadDataCompleted Événement
Définition
Important
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Se produit lors d'une opération asynchrone de téléchargement de données.
public:
event System::Net::DownloadDataCompletedEventHandler ^ DownloadDataCompleted;
public event System.Net.DownloadDataCompletedEventHandler? DownloadDataCompleted;
public event System.Net.DownloadDataCompletedEventHandler DownloadDataCompleted;
member this.DownloadDataCompleted : System.Net.DownloadDataCompletedEventHandler
Public Custom Event DownloadDataCompleted As DownloadDataCompletedEventHandler
Public Event DownloadDataCompleted As DownloadDataCompletedEventHandler
Type d'événement
Exemples
L’exemple de code suivant montre comment définir un gestionnaire d’événements pour cet événement.
// 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
L’exemple de code suivant montre une implémentation d’un gestionnaire pour cet événement.
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
Cet événement est déclenché chaque fois qu’une opération de téléchargement de données asynchrone se termine. Les téléchargements de données asynchrones sont démarrés en appelant les DownloadDataAsync méthodes.
DownloadDataCompletedEventHandler est le délégué de cet événement. La DownloadDataCompletedEventArgs classe fournit au gestionnaire d’événements des données d’événement.
Pour plus d’informations sur la façon de gérer les événements, consultez gestion et déclenchement d’événements.
S’applique à
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