What is the difference between @Component, @Service, @Repository, and @Controller? @Component, @Service, @Repository और @Controller में क्या अंतर है?

All four are stereotype annotations built on top of @Component, so all are detected by component scanning and registered as beans — functionally, Spring treats them the same way for the purpose of bean registration. The distinction is semantic and enables extra framework behavior for each layer.

@Repository additionally enables automatic translation of persistence-related exceptions into Spring's unified DataAccessException hierarchy. @Service marks business/service-layer logic (behaves like plain @Component, mainly documentation-level distinction). @Controller marks a Spring MVC web controller that returns view names, and @RestController (which combines @Controller + @ResponseBody) marks a REST endpoint. Using the correct stereotype communicates architectural intent and unlocks layer-specific tooling like AOP pointcuts targeting @Service classes.

@Repository public interface UserRepository extends JpaRepository<User, Long> {}
@Service public class UserService { }
@RestController public class UserController { }