DownloadStringCompletedEventHandler Делегат

Определение

Представляет метод, обрабатывающий событие DownloadStringCompleted объекта WebClient.Represents the method that will handle the DownloadStringCompleted event of a WebClient.

public delegate void DownloadStringCompletedEventHandler(System::Object ^ sender, DownloadStringCompletedEventArgs ^ e);
public delegate void DownloadStringCompletedEventHandler(object sender, DownloadStringCompletedEventArgs e);
type DownloadStringCompletedEventHandler = delegate of obj * DownloadStringCompletedEventArgs -> unit
Public Delegate Sub DownloadStringCompletedEventHandler(sender As Object, e As DownloadStringCompletedEventArgs)

Параметры

sender
Object

Источник события.The source of the event.

e
DownloadStringCompletedEventArgs

Объект DownloadStringCompletedEventArgs, содержащий данные события.A DownloadStringCompletedEventArgs that contains event data.

Наследование
DownloadStringCompletedEventHandler

Примеры

В следующем примере кода демонстрируется асинхронная загрузка строки.The following code example demonstrates downloading a string asynchronously.

// Sample call : DownloadStringInBackground2 ("http://www.contoso.com/GameScores.html");
void DownloadStringInBackground2( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);
   
   // Specify that the DownloadStringCallback2 method gets called
   // when the download completes.
   client->DownloadStringCompleted += gcnew DownloadStringCompletedEventHandler( DownloadStringCallback2 );
   client->DownloadStringAsync( uri );
}


// Sample call : DownloadStringInBackground2 ("http://www.contoso.com/GameScores.html");
public static void DownloadStringInBackground2 (string address)
{
    WebClient client = new WebClient ();
    Uri uri = new Uri(address);

    // Specify that the DownloadStringCallback2 method gets called
    // when the download completes.
    client.DownloadStringCompleted += new DownloadStringCompletedEventHandler (DownloadStringCallback2);
    client.DownloadStringAsync (uri);
}

'  Sample call : DownloadStringInBackground2 ("http:' www.contoso.com/GameScores.html")
Public Shared Sub DownloadStringInBackground2(ByVal address As String)

    Dim client As WebClient = New WebClient()

    '  Specify that the DownloadStringCallback2 method gets called
    '  when the download completes.
    AddHandler client.DownloadStringCompleted, AddressOf DownloadStringCallback2
                Dim uri as Uri = New Uri(address)
    client.DownloadStringAsync(uri)
End Sub

При завершении загрузки вызывается следующий метод.The following method is called when the download completes.

void DownloadStringCallback2( Object^ /*sender*/, DownloadStringCompletedEventArgs^ e )
{
   
   // If the request was not canceled and did not throw
   // an exception, display the resource.
   if (  !e->Cancelled && e->Error == nullptr )
   {
      String^ textString = dynamic_cast<String^>(e->Result);
      Console::WriteLine( textString );
   }
}


private static void DownloadStringCallback2 (Object sender, DownloadStringCompletedEventArgs e)
{
    // If the request was not canceled and did not throw
    // an exception, display the resource.
    if (!e.Cancelled && e.Error == null)
    {
        string textString = (string)e.Result;

        Console.WriteLine (textString);
    }
}

Private Shared Sub DownloadStringCallback2(ByVal sender As Object, ByVal e As DownloadStringCompletedEventArgs)

    '  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 textString As String = CStr(e.Result)
        Console.WriteLine(textString)
    End If
End Sub

Комментарии

При создании делегата DownloadStringCompletedEventHandler необходимо указать метод, обрабатывающий событие.When you create a DownloadStringCompletedEventHandler delegate, you identify the method that will handle the event. Чтобы связать событие с обработчиком событий, нужно добавить в событие экземпляр делегата.To associate the event with your event handler, add an instance of the delegate to the event. Обработчик событий вызывается всякий раз, когда происходит событие, если делегат не удален.The event handler is called whenever the event occurs, unless you remove the delegate. Дополнительные сведения о делегатах обработчиков событий см. в разделе обработка и вызов событий.For more information about event handler delegates, see Handling and Raising Events.

Методы расширения

GetMethodInfo(Delegate)

Получает объект, представляющий метод, представленный указанным делегатом.Gets an object that represents the method represented by the specified delegate.

Применяется к