OpenWriteCompletedEventHandler Delegato

Definizione

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

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

Parametri

sender
Object

Origine dell'evento.The source of the event.

e
OpenWriteCompletedEventArgs

Oggetto OpenWriteCompletedEventArgs contenente i dati dell'evento.A OpenWriteCompletedEventArgs containing event data.

Ereditarietà
OpenWriteCompletedEventHandler

Esempi

Nell'esempio di codice seguente viene illustrata l'apertura di un flusso per la scrittura dei dati da caricare.The following code example demonstrates opening a stream to write data to be uploaded.

void OpenResourceForPosting( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);
   
   // Specify that the OpenWriteCallback method gets called
   // when the writeable stream is available.
   client->OpenWriteCompleted += gcnew OpenWriteCompletedEventHandler( OpenWriteCallback2 );
   client->OpenWriteAsync( uri );
   
   // Applications can perform other tasks
   // while waiting for the upload to complete.
}


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

    // Specify that the OpenWriteCallback method gets called
    // when the writeable stream is available.
    client.OpenWriteCompleted += new OpenWriteCompletedEventHandler (OpenWriteCallback2);
    client.OpenWriteAsync (uri);
    // Applications can perform other tasks
    // while waiting for the upload to complete.
}

Public Shared Sub OpenResourceForPosting(ByVal address As String)

    Dim client As WebClient = New WebClient()
    '  Specify that the OpenWriteCallback method gets called
    '  when the writeable stream is available.
    AddHandler client.OpenWriteCompleted, AddressOf OpenWriteCallback2
                Dim uri as Uri = New Uri(address)
    client.OpenWriteAsync(uri)
    '  Applications can perform other tasks
    '  while waiting for the upload to complete.
End Sub

Il metodo seguente viene chiamato quando il flusso è disponibile.The following method is called when the stream is available.

void OpenWriteCallback2( Object^ /*sender*/, OpenWriteCompletedEventArgs^ e )
{
   Stream^ body = nullptr;
   StreamWriter^ s = nullptr;
   try
   {
      body = dynamic_cast<Stream^>(e->Result);
      s = gcnew StreamWriter( body );
      s->AutoFlush = true;
      s->Write( "This is content data to be sent to the server." );
   }
   finally
   {
      if ( s != nullptr )
      {
         s->Close();
      }
      if ( body != nullptr )
      {
         body->Close();
      }
   }

}


private static void OpenWriteCallback2 (Object sender, OpenWriteCompletedEventArgs e)
{
    Stream body = null;
    StreamWriter s = null;

    try
    {
        body = (Stream)e.Result;
        s = new StreamWriter (body);
        s.AutoFlush = true;
        s.Write ("This is content data to be sent to the server.");
    }
    finally
    {
        if (s != null)
        {
            s.Close ();
        }

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

Private Shared Sub OpenWriteCallback2(ByVal sender As Object, ByVal e As OpenWriteCompletedEventArgs)

    Dim body As Stream = Nothing
    Dim s As StreamWriter = Nothing

    Try

        body = CType(e.Result, Stream)
        s = New StreamWriter(body)
        s.AutoFlush = True
        s.Write("This is content data to be sent to the server.")
    Finally

        If Not s Is Nothing Then

            s.Close()
        End If

        If Not body Is Nothing Then

            body.Close()
        End If
    End Try
End Sub

Commenti

Quando si crea un delegato OpenWriteCompletedEventHandler, si identifica il metodo che gestirà l'evento.When you create a OpenWriteCompletedEventHandler 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)

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