4.2.8. AppContext

AppContext is a system class, which stores references to certain common components for each application block in its static fields:

  • ApplicationContext of Spring Framework.

  • Set of application properties loaded from app.properties files.

  • ThreadLocal variable, storing SecurityContext instances.

  • Collection of application lifecycle listeners (AppContext.Listener).

When the application is started, AppContext is initialized using loader classes, specific for each application block:

  • Middleware loader – AppContextLoader

  • Web Client loader – WebAppContextLoader

  • Web Portal loader – PortalAppContextLoader

  • Desktop Client loader – DesktopAppContextLoader

AppContext can be used in the application code for the following tasks:

  • Registering listeners, triggered after full initialization and before termination of the application, for example:

    AppContext.addListener(new AppContext.Listener() {
    @Override
    public void applicationStarted() {
        System.out.println("Application is ready");
    }

    @Override
    public void applicationStopped() {
        System.out.println("Application is closing");
    }
});

    At the moment of applicationStarted() call:

    • All the beans are fully initialized and their @PostConstruct methods are executed.

    • Static AppBeans.get() methods can be used for obtaining beans.

    • The AppContext.isStarted() method returns true.

    • The AppContext.isReady() method returns false.

    • If cuba.automaticDatabaseUpdate application property is enabled, all database update scripts are successfully executed (in the Middleware block).

    At the moment of applicationStopped() call:

    • All the beans are operational and can be obtained via AppBeans.get() methods.

    • AppContext.isStarted() method returns false.

    • The AppContext.isReady() method returns false.

    A real example of using AppContext.Listener can be found in Running Code at Application Start.

  • Getting the application property values, stored in app.properties files in case they are not available through configuration interfaces.

  • Passing SecurityContext to new execution threads, see User Authentication.