OpenReadCompletedEventHandler OpenReadCompletedEventHandler OpenReadCompletedEventHandler OpenReadCompletedEventHandler Delegate

Definizione

Rappresenta il metodo che gestirà l'evento OpenReadCompleted di un oggetto WebClient.Represents the method that will handle the OpenReadCompleted event of a WebClient.

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

Parametri

sender
Object Object Object Object

Origine dell'evento.The source of the event.

Ereditarietà
OpenReadCompletedEventHandlerOpenReadCompletedEventHandlerOpenReadCompletedEventHandlerOpenReadCompletedEventHandler

Esempi

Nell'esempio di codice riportato di seguito viene illustrato il download di una risorsa per la lettura.The following code example demonstrates downloading a resource for reading.

void OpenResourceForReading2( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);

   client->OpenReadCompleted += gcnew OpenReadCompletedEventHandler( OpenReadCallback2 );
   client->OpenReadAsync( uri );
}


public static void OpenResourceForReading2 (string address)
{
    WebClient client = new WebClient ();
    Uri uri = new Uri(address);

    client.OpenReadCompleted += new OpenReadCompletedEventHandler(OpenReadCallback2);
    client.OpenReadAsync (uri);
}

Public Shared Sub OpenResourceForReading2(ByVal address As String)

    Dim client As WebClient = New WebClient()
    AddHandler client.OpenReadCompleted, AddressOf OpenReadCallback2
                Dim uri as Uri = New Uri(address)
    client.OpenReadAsync(uri)                        
End Sub

Il metodo seguente viene chiamato al termine del download.The following method is called when the download completes.

void OpenReadCallback2( Object^ /*sender*/, OpenReadCompletedEventArgs^ e )
{
   Stream^ reply = nullptr;
   StreamReader^ s = nullptr;
   try
   {
      reply = dynamic_cast<Stream^>(e->Result);
      s = gcnew StreamReader( reply );
      Console::WriteLine( s->ReadToEnd() );
   }
   finally
   {
      if ( s != nullptr )
      {
         s->Close();
      }
      if ( reply != nullptr )
      {
         reply->Close();
      }
   }

}


private static void OpenReadCallback2 (Object sender, OpenReadCompletedEventArgs e)
{
    Stream reply = null;
    StreamReader s = null;

    try
    {
        reply = (Stream)e.Result;
        s = new StreamReader (reply);
        Console.WriteLine (s.ReadToEnd ());
    }
    finally
    {
        if (s != null)
        {
            s.Close ();
        }

        if (reply != null)
        {
            reply.Close ();
        }
    }
}

Private Shared Sub OpenReadCallback2(ByVal sender As Object, ByVal e As OpenReadCompletedEventArgs)

    Dim reply As Stream = Nothing
    Dim s As StreamReader = Nothing

    Try

        reply = CType(e.Result, Stream)
        s = New StreamReader(reply)
        Console.WriteLine(s.ReadToEnd())
    Finally

        If Not s Is Nothing Then

            s.Close()
        End If

        If Not reply Is Nothing Then

            reply.Close()
        End If
    End Try
End Sub

Commenti

Quando si crea un delegato OpenReadCompletedEventHandler, si identifica il metodo che gestirà l'evento.When you create a OpenReadCompletedEventHandler delegate, you identify the method that will handle the event. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato.To associate the event with your event handler, add an instance of the delegate to the event. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato.The event handler is called whenever the event occurs, unless you remove the delegate.

Metodi di estensione

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato.Gets an object that represents the method represented by the specified delegate.

Si applica a