OpenWriteCompletedEventHandler 委托

定义

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)

参数

继承

Object

Delegate

OpenWriteCompletedEventHandler

示例

下面的代码示例演示如何打开流以写入要上载的数据。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

当流可用时, 将调用以下方法。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

注解

创建 OpenWriteCompletedEventHandler 委托时，需要标识将处理该事件的方法。When you create a OpenWriteCompletedEventHandler delegate, you identify the method that will handle the event. 若要将事件与事件处理程序关联，请将该委托的一个实例添加到事件中。To associate the event with your event handler, add an instance of the delegate to the event. 除非移除了该委托，否则每当发生该事件时就会调用事件处理程序。The event handler is called whenever the event occurs, unless you remove the delegate.

扩展方法

适用于