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lifecycle

  • The lifecycle of a Spring bean consists of several stages, from instantiation to destruction.
  • performing initialization
  • performing cleanup tasks.
  • fact: don't use aware, better way is to inject. 
    @Autowired    private BeanFactory beanFactory;
@Autowired    private ApplicationContext applicationContext;

stages : bean's lifecycle

1.Instantiation And populate Properties: - The bean is created using its constructor or a factory method. - Dependencies and properties are set on the bean, either through setters or fields.

  1. Aware Interfaces:
  2. If the bean implements Aware interface
  3. BeanNameAware,
  4. BeanClassLoaderAware,

  5. BeanFactoryAware, or ApplicationContextAware,etc

    • Note: can also @autowired them directly.

  6. BeanPostProcessors:

  7. hooks for customizing the bean lifecycle,
  8. If there are any BeanPostProcessor implementations registered in the context, they are applied.
  9. These can modify the bean instance before and after initialization, which is next step.

bean is Constructed

  1. Initialization:
  2. If the bean implements InitializingBean, Spring calls its afterPropertiesSet() method.
  3. @PostConstruct annotated method is called.

Ready for Use

  1. Destruction:

  2. If the bean implements DisposableBean, Spring calls its "destroy()" method, when the bean is no longer needed. -@PreDestroy annotated method, it is called.

  3. Destroy:

  4. The bean is destroyed and its resources are released.

More Notes:

  • It's important to note that not all beans go through every stage of the lifecycle.
  • For example, beans that are singleton-scoped only go through the lifecycle once,
  • while prototype-scoped beans go through the lifecycle each time they are requested from the container.