The Spring @Controller and @RestController Annotations

Table of Contents

1. Overview
2. Spring MVC @Controller
3. Spring MVC @RestController
4. Conclusion

1. Overview

In this brief tutorial, we’ll discuss the difference between @Controller and @RestController annotations in Spring MVC.

We can use the first annotation for traditional Spring controllers, and it has been part of the framework for a very long time.

Spring 4.0 introduced the @RestController annotation in order to simplify the creation of RESTful web services. It’s a convenient annotation that combines @Controller and @ResponseBody, which eliminates the need to annotate every request handling method of the controller class with the @ResponseBody annotation.

2. Spring MVC @Controller

We can annotate classic controllers with the @Controller annotation. This is simply a specialization of the @Component class, which allows us to auto-detect implementation classes through the classpath scanning.

We typically use @Controller in combination with a @RequestMapping annotation for request handling methods.

Let’s see a quick example of the Spring MVC controller:

@Controller
@RequestMapping("books")
public class SimpleBookController {

    @GetMapping("/{id}", produces = "application/json")
    public @ResponseBody Book getBook(@PathVariable int id) {
        return findBookById(id);
    }

    private Book findBookById(int id) {
        // ...
    }
}

We annotated the request handling method with @ResponseBody. This annotation enables automatic serialization of the return object into the HttpResponse.

3. Spring MVC @RestController

@RestController is a specialized version of the controller. It includes the @Controller and @ResponseBody annotations, and as a result, simplifies the controller implementation:

@RestController
@RequestMapping("books-rest")
public class SimpleBookRestController {
    
    @GetMapping("/{id}", produces = "application/json")
    public Book getBook(@PathVariable int id) {
        return findBookById(id);
    }

    private Book findBookById(int id) {
        // ...
    }
}

The controller is annotated with the @RestController annotation; therefore, the @ResponseBody isn’t required.

Every request handling method of the controller class automatically serializes return objects into HttpResponse.