WebClient.OpenReadCompleted Evento

Definizione

Spazio dei nomi:

System.Net

Assembly:

System.Net.WebClient.dll

Origine:

WebClient.cs

Si verifica al completamento di un'operazione asincrona di apertura di un flusso contenente una risorsa.

public:
 event System::Net::OpenReadCompletedEventHandler ^ OpenReadCompleted;

public event System.Net.OpenReadCompletedEventHandler? OpenReadCompleted;

member this.OpenReadCompleted : System.Net.OpenReadCompletedEventHandler 

Public Custom Event OpenReadCompleted As OpenReadCompletedEventHandler 

Tipo evento

OpenReadCompletedEventHandler

Esempio

Nell'esempio di codice seguente viene illustrata l'impostazione di un gestore eventi per questo evento.

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

Nell'esempio di codice seguente viene illustrata un'implementazione di un gestore per questo evento.

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

Questo evento viene generato ogni volta che viene completata un'operazione asincrona per aprire un flusso contenente una risorsa. Queste operazioni vengono avviate chiamando i OpenReadAsync metodi .

OpenReadCompletedEventHandler è il delegato per questo evento. La OpenReadCompletedEventArgs classe fornisce al gestore eventi i dati dell'evento.

Per altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.