Using @Service to Replace @Controller in Spring Boot

In Spring Boot development, @Controller and @Service are the two most frequently used annotations. This article explores whether @Service can be used to annotate a controller layer and still handle web requests.

It explains that @Controller marks a class as a web controller handling HTTP requests, while @Service marks a class as a service handling business logic. Both annotations are detected by component scanning based on @SpringBootApplication, which includes @EnableAutoConfiguration, @ComponentScan, and @Configuration.

Because @ComponentScan registers any class annotated with @Controller, @Service, @Repository, or @Component, a class annotated only with @Service can still be registered in the Spring container. If the class also carries @RequestMapping (or method‑level mapping annotations), Spring MVC will treat it as a handler.

Example code:

@Service
@RequestMapping("/ts")
public class ServiceController {
    @Autowired
    UserMapper userMapper;

    @GetMapping("get-services")
    @ResponseBody
    public User getServices() {
        User user = userMapper.selectOne(Wrappers.lambdaQuery(User.class)
                .eq(User::getUsername, "zhangSan"));
        return user;
    }
}

A GET request to http://localhost:8080/ts/get-services returns a JSON payload with the user data, demonstrating that the @Service‑annotated class successfully handles the request.

The article further details the bean registration process: SpringApplication.run creates the application context, ConfigurationClassPostProcessor scans for bean definitions, and AbstractHandlerMethodMapping binds URLs to handler methods based on @RequestMapping metadata.

In summary, as long as a class is registered as a bean (e.g., via @Service) and contains request‑mapping annotations, Spring Boot can route HTTP requests to it just like a traditional @Controller.