Using @Service to Replace @Controller in Spring Boot: Principles and Example

In Spring Boot development the @Controller and @Service annotations are the most frequently used, but this article explores whether @Service can replace @Controller for handling web requests.

We define a class ServiceController annotated with @Service and @RequestMapping, inject a UserMapper via @Autowired, and expose a GET endpoint /ts/get-services that returns a User object.

@Service
@RequestMapping("/ts")
public class ServiceController {

    @Autowired
    private UserMapper userMapper;

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

Sending a GET request to http://localhost:8080/ts/get-services returns JSON data, demonstrating that the @Service‑annotated class can handle HTTP requests just like a @Controller.

The underlying reason is that Spring’s component scanning (triggered by @SpringBootApplication) registers both @Controller and @Service beans, and the request mapping infrastructure ( AbstractHandlerMethodMapping) processes any bean that carries @RequestMapping, regardless of whether it is marked as a controller.

Thus, as long as a class is discovered as a bean and contains mapping annotations, Spring MVC will treat it as a handler, allowing @Service to serve the same purpose as @Controller.

In summary, @Service can be used to annotate a class that handles web requests, provided it is scanned and contains @RequestMapping (or related) annotations; the request handling flow remains identical to that of a traditional @Controller.