WebClient.OpenReadCompleted 事件

  • 參考

定義

命名空間:
System.Net
組件:
System.Net.WebClient.dll
組件:
System.dll
組件:
netstandard.dll
來源:
WebClient.cs
來源:
WebClient.cs
來源:
WebClient.cs

在開啟包含資源之資料流的非同步作業完成時發生。

public:
 event System::Net::OpenReadCompletedEventHandler ^ OpenReadCompleted;
public event System.Net.OpenReadCompletedEventHandler? OpenReadCompleted;
public event System.Net.OpenReadCompletedEventHandler OpenReadCompleted;
member this.OpenReadCompleted : System.Net.OpenReadCompletedEventHandler 
Public Custom Event OpenReadCompleted As OpenReadCompletedEventHandler 
Public Event OpenReadCompleted As OpenReadCompletedEventHandler

事件類型

OpenReadCompletedEventHandler

範例

下列程式代碼範例示範如何為此事件設定事件處理程式。

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

下列程式代碼範例示範這個事件的處理程序實作。

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

備註

每次開啟包含資源之數據流的異步操作時，都會引發此事件。 這些作業會藉由呼叫 OpenReadAsync 方法來啟動。

OpenReadCompletedEventHandler是這個事件的委派。 類別 OpenReadCompletedEventArgs 會提供事件處理程式與事件數據。

如需如何處理事件的詳細資訊，請參閱 處理和引發事件。

適用於