Spring Boot 3 Core: Dependency Injection, IoC Container & Bean Lifecycle
Master Spring Boot 3 application architecture: Inversion of Control (IoC), Dependency Injection (`@Autowired`, Constructor Injection), Component Scanning, `@Bean`, and Bean Lifecycles.
Spring Inversion of Control Container
### Spring IoC Container Mechanics
1. **Bean Instantiation**: Spring scans annotated classes (`@Component`, `@Service`, `@Repository`, `@Controller`) and instantiates managed object instances (Beans).
2. **Dependency Injection**: Spring injects dependent bean references via Constructor Injection automatically.
3. **Bean Scopes**: Singleton (default), Prototype, Request, Session.