OpenReadCompletedEventHandler Delegate

Definition

Namespace:

System.Net

Assembly:

System.Net.WebClient.dll

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)

Parameters

sender

Object

The source of the event.

e

OpenReadCompletedEventArgs

A OpenReadCompletedEventArgs containing event data.

Examples

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

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

Remarks

When you create a OpenReadCompletedEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate.

Extension Methods

GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.