The IoC (Inversion of Control) Container is the core component of the Spring Framework responsible for creating, configuring, and managing Spring Beans. It controls the lifecycle of objects and automatically injects required dependencies, enabling loose coupling between application components.
Key Points: • The IoC container creates and manages Spring Beans throughout their lifecycle. • It performs Dependency Injection (DI) by automatically providing required dependencies to beans. • It reduces tight coupling between components, making applications easier to maintain and test. • The container reads configuration metadata from annotations, Java configuration classes, or XML files. • Common IoC container implementations in Spring are BeanFactory and ApplicationContext.
Example: In a Spring application, if a UserService depends on a UserRepository, the IoC container creates both objects and automatically injects the UserRepository into the UserService without requiring manual object creation.
Code Example:
@Service
public class UserService {
@Autowired
private UserRepository userRepository;
}Interview Tip: A concise interview answer is:
"The IoC container is the core of Spring. It manages the creation, configuration, and lifecycle of beans and automatically injects dependencies, helping build loosely coupled, maintainable, and testable applications."