OSGiJavaFXUsage

This illustrates the usage of winnall/OSGiJavaFX.

The service Usage.java creates an instance of JavaFXLauncher (from winnall/OSGiJavaFX). The name of the JavaFX Application to be executed is passed to the method JavaFXLauncher.launch(). This Application must be implemented by subclassing AbstractJavaFXApplication, which is abstract only in concept (i.e. it is NOT an abstract class). In the case implemented in this example the application is the classic JavaFX "hello world".

The class HelloWorld.java contains the "hello world" application. Note that this class may NOT be compiled as a declarative service NOR as a main class replacement as is typical with JavaFX POJOs.

HelloWorld.java extends AbstractJavaFXApplication and the following conditions have to be fulfilled:

• HellWorld.init() must call super.init() (implicitly – as here – or explicitly), which registers the current class (this) as an OSGi service even though it has been created under JavaFX control. A variable protected BundleContext bundlecontext, which refers to the OSGi service thus registered, is also made available.
• HelloWorld.start() must call super.start(primaryStage) to make primaryStage available to its superclass and the two onStage() methods defined there; otherwise these two methods will not work.

If other OSGi services are to be referenced in HelloWorld (which is not the case in the present example), they can be made available with code similar to the following:

  private XXX xxx;  // to hold the reference to the required service
  private ServiceTracker<XXX, XXX> xxxTracker;
  
  public void init() {
    super.init();
    try {
      // bundleContext is declared in the superclass
      xxxTracker = new ServiceTracker<>(bundleContext, XXX.class, null);
      xxxTracker.open();
      xxx = xxxTracker.waitForService(0);
    }...
  }

It is probably best – when using a ServiceTracker as above – to clean up on termination as follows:

  public void stop() {
    super.stop();
    xxxTracker.close();
  }

HelloWorld.java looks in all other respects exactly the same as any other non-OSGi JavaFX start-up class.

The accompanying pom.xml directs Maven to compile OSGiJavaFXUsage and places all the relevant JARs (including the one from winnall/OSGiJavaFX) into the directory target/deploy. If all the files in this directory are deployed appropriately into Karaf or another OSGi framework (or Felix, anyway), the "hello world" application runs.