4.2.7. 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 Section 5.8.4, “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 Section 4.2.10, “User Authentication ”.

Use injection or static methods of AppBeans class to obtain references to Spring beans.

It is not recommended to use AppContext.getApplicationContext().getBean().

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