问如何在Swing中关闭嵌入式JavaFX应用程序？

EN

public class YoutubeVideoPlayer extends Application {
   public static void main(String[] args) {
      launch(args);
   }
   @Override
   public void start(Stage primaryStage) throws Exception{
        WebView webView = new WebView();
        webView.getEngine().load("https://www.youtube.com/embed/6uL3SHfllh8");

        webView.setPrefSize( 300 , 300);

        primaryStage.setScene( new Scene( webView ) );
        primaryStage.show();

        primaryStage.setOnCloseRequest(new EventHandler<WindowEvent>(){
            @Override
            public void handle(WindowEvent we) {
               Platform.setImplicitExit(true);
               primaryStage.close();
               Platform.exit();
            }
        });        
   }
}