JavaFx in headless mode

Question

Is it possible to run JavaFx in headless mode(in Java 7)? It is being used to generate images on the server but is asking for an X-Server. Does there exist something like ja

Answer 1

I have an application that can be used interactively (displaying JavaFx dialogs) but also must be able to run non-interactive on a server without display.
Even though no GUI element is used in non-interactive mode, we got

    Caused by: java.lang.UnsupportedOperationException: Unable to open DISPLAY
    at com.sun.glass.ui.gtk.GtkApplication.<init>(GtkApplication.java:68)

This happens as soon as a class derived from javafx.application.Application is instantiated, which you normally do with your main class.

Here is the way I solved the problem:

• I created an additional class GuiAppExecution:

  import java.util.List;
  
  import javafx.application.Application;
  import javafx.stage.Stage;
  
  /**
   * JavaFx launch class for {@link AppExecution}.
   */
  public class GuiAppExecution extends Application {
  
    @Override
    public void start(Stage stage) throws Exception {
      List<String> parameters = getParameters().getRaw();
      AppExecution appExecution = new AppExecution();
      appExecution.launch(parameters);
    }
  
    /**
     * Launches the {@link AppExecution} as JavaFx {@link Application}.
     *
     * @param parameters program parameters
     */
    public void launchGui(String[] parameters) {
      launch(parameters);
    }
  }
  

• In the main class AppExecution I created a method
  public void launch(List<String> parameters) {
  which parses the parameters and launches the application for both interactive and non-interactive execution.

• The main method looks like this:

  public static void main(String[] parameters) {
    List<String> parameterList = Arrays.asList(parameters);
    if (parameterList.stream().anyMatch(p -> p.equalsIgnoreCase(BATCH_PARAMETER))) {
      AppExecution appExecution = new AppExecution();
      appExecution.launch(parameterList);
    }
    else {
      GuiAppExecution guiAppExecution = new GuiAppExecution();
      guiAppExecution.launchGui(parameters);
    }
  }
  

  with

  private static final String BATCH_PARAMETER = "-batch";
  

  as the program option that request the non-interactive execution.

Since GuiAppExecution (which is derived from javafx.application.Application) is not instantiated for non-interactive execution, the JavaFx environment is not started.

Answer 2

Answer by Shreyas Dave didn't work for me anymore. Though I don't know why, here is what I did:

public static void main(String[] args) {
    // to avoid
    // [JRSAppKitAWT markAppIsDaemon]: Process manager already initialized: can't fully enable headless mode.
    System.setProperty("javafx.macosx.embedded", "true");
    java.awt.Toolkit.getDefaultToolkit();
    // end
    launch(args);
}

This was also pointed out here: JavaFX screencapture headless exception on OSX

Answer 3

Here is how I solved this problem for server-side image geneartion on Ubuntu linux environment with jetty application server. It uses xvfb but only as a "library" - without any additional special actions on server:

apt-get install xvfb

// then on application server start:

export DISPLAY=":99"

start-stop-daemon --start --background --user jetty --exec "/usr/bin/sudo" -- -u jetty /usr/bin/Xvfb :99 -screen 0 1024x768x24

You can see the details of my server-side image generation solution in this SO question.

Answer 4

This is a kind of problem which I encountered while capturing images in Mac OS.

I have solved this issue by using

static {

        System.setProperty("java.awt.headless", "false");
}

See for reference : Headless environment error in java.awt.Robot class with MAC OS

Answer 5

If you have the source code of the JavaFX application you could also try to use TestFX run the application in a headless mode, to control it and to make screenshots. To run your TestFX application in headless mode you have to start it with the following JVM parameters (to enable Monocle):

-Dtestfx.robot=glass -Dglass.platform=Monocle -Dmonocle.platform=Headless -Dprism.order=sw

Moreover you might need to install Monocle first. See Headless testing with JavaFx and TestFx for more information.