When you’re using a object based on its interface, you don’t have to concern yourself with the implementation because it’s abstracted from you. At runtime, the implementation used depends on your environment and your app’s configuration. Liferay DXP offers several standard ways to register implementations and inject them into your applications.
Contexts and Dependency Injection (CDI): Is the Java EE standard dependency
injection mechanism. Liferay DXP’s CDI bean container makes an application’s
concrete classes available as beans. Bean classes can user other beans by way of
injecting them into their fields that have the @Inject annotation.
OSGi Declarative Services: Liferay DXP’s OSGi runtime framework allows
components to register as service provides and other components can call on the
registry to bind the services to their fields that have the @Reference
annotation. Liferay DXP’s services and services you create using Service
Builder are available as
OSGi Declarative Services.
Spring DI: The Spring framework includes inversion of control (IoC) and dependency injection. It’s available to applications that configure the Spring framework.
As an added bonus, Liferay DXP provides OSGi CDI integration. It lets you publish CDI beans as OSGi services and consume OSGi services in your CDI beans. Which dependency injection mechanism will you use? Read on to learn more about them.