OpenWriteCompletedEventHandler Delegar

Definição

Namespace:

System.Net

Assemblies:

netstandard.dll, System.Net.WebClient.dll

Origem:

WebClient.cs

Representa o método que manipulará o evento de OpenWriteCompleted de 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)

Parâmetros

sender

Object

A fonte do evento.

e

OpenWriteCompletedEventArgs

Um OpenWriteCompletedEventArgs que contém dados de evento.

Exemplos

O exemplo de código a seguir demonstra como abrir um fluxo para gravar dados a serem carregados.

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

O método a seguir é chamado quando o fluxo está disponível.

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

Comentários

Ao criar um OpenWriteCompletedEventHandler delegado, você identifica o método que manipulará o evento. Para associar o evento ao manipulador de eventos, adicione uma instância do delegado ao evento. O manipulador de eventos é chamado sempre que o evento ocorre, a menos que você remova o representante.

Métodos de Extensão

Nome	Description
GetMethodInfo(Delegate)	Obtém um objeto que representa o método representado pelo delegado especificado.