@Component Annotation

@Component is a class level annotation to declare class as component.

Spring IoC container owns the complete responsibility to manage component, automatically detect and register component as part of application context which is nothing but an IOC container.

A component is a reusable and self-contained module within an application.

Specialized annotations like @Service, @Repository, and @Controller are meta-annotations of @Component.

@ComponentScan annotation scans all the required packages to detect and register classes annotated with @Component-annotation.

Here, TestComponent is marked with @Component, so Spring Boot will automatically detect and register it as a bean.

It is Spring’s responsibility to create, manage and destroy component class instance.

Below is the syntax to declare component class:

Below is one of the way to inject component using @Autowired annotation.

Classes annotated with @Component can be injected into other Spring beans using @Autowired with the help of constructor.

Conclusion:

• The @Component annotation in Spring Boot is used to declare a class as a Spring-managed component, allowing the IoC container to detect, register, and manage it automatically.
• Components are self-contained, reusable modules essential for application development. Specialized annotations like @Service, @Repository, and @Controller extend @Component, offering additional semantics for specific use cases.
• Spring’s @ComponentScan annotation ensures that all required packages are scanned to detect and register @Component-annotated classes. Once registered, Spring takes full responsibility for creating, managing, and destroying component instances as needed.