IoC Containers : ApplicationContext vs BeanFactory

1. BeanFactory

• Definition: The simplest IoC container, responsible for instantiating, configuring, and managing beans.
• Features:
  • Lazy initialization (bean created only when requested).
  • Lightweight, suitable for simple applications with limited resources.
• Usage (rare nowadays):

BeanFactory factory = new XmlBeanFactory(new ClassPathResource("beans.xml"));
MyService service = factory.getBean("myService", MyService.class);

2. ApplicationContext

• Definition: A superset of BeanFactory with more enterprise-level features.
• Features:
  • Eager initialization (beans created at startup, faster runtime access).
  • Supports internationalization (i18n), event publishing, annotation-based config, @Autowired, @ComponentScan.
  • Commonly used in all modern Spring Boot applications.
• Usage:

ApplicationContext context =
    new ClassPathXmlApplicationContext("beans.xml");
MyService service = context.getBean("myService", MyService.class);

Key Difference

✅ In Spring Boot → ApplicationContext is the default IoC container (AnnotationConfigApplicationContext / ServletWebServerApplicationContext).