Inversion of Control

The IoC (Inversion of Control) container is a fundamental part of the Spring framework. It’s the core component responsible for the instantiation, configuration, and management of Beans in a Spring application.

Some key things to know about the Spring IoC container:

1. Dependency Injection: The IoC container is responsible for injecting dependencies into Beans. This is the “Inversion of Control” aspect, where the container controls the creation and injection of dependencies, rather than the Beans themselves.

2. Configuration: The IoC container is configured using either XML configuration files or Java-based configuration using annotations like @Configuration and @Bean.

3. Bean Management: The container is responsible for the full lifecycle management of Beans, including instantiation, dependency resolution, and destruction.

4. Bean Scopes: The IoC container supports different Bean scopes, such as singleton, prototype, request, session, and application, which determine how the container manages the instances of each Bean.

5. Bean Factories: The IoC container is implemented by two main interfaces: BeanFactory and ApplicationContext. BeanFactory is the basic IoC container, while ApplicationContext is an extension that adds more enterprise-specific functionality.

6. Autowiring: The IoC container can automatically “wire” Beans together by matching their dependencies, reducing the amount of configuration required.

The IoC container is the heart of the Spring framework. It allows developers to focus on writing the application logic without worrying about the creation and management of the objects that make up the application. This promotes loose coupling, testability, and maintainability of the codebase.