Difference between @Controller vs @RestController in Spring
When developing web applications using the Spring framework, you may come across two annotations: @Controller and @RestController. While both are used for handling HTTP requests, there are some key differences between them. In this article, we will explore these differences and understand when to use each annotation.
@Controller Annotation
The @Controller annotation is used to mark a class as a controller in the Spring MVC framework. It is typically used to handle traditional web applications where the response is rendered using a view technology, such as JSP or Thymeleaf.
A controller class annotated with @Controller can have methods annotated with @RequestMapping or other request mapping annotations to handle specific HTTP requests. These methods return a logical view name or a ModelAndView object, which is resolved by the view resolver to render the response.
Here's an example of a controller class using @Controller:
@Controller
public class MyController {
@RequestMapping("/hello")
public String hello() {
return "hello"; // returns the logical view name
}
}
@RestController Annotation
The @RestController annotation, introduced in Spring 4, combines the @Controller and @ResponseBody annotations. It is used to create RESTful web services that return JSON or XML responses directly, without the need for a view resolver.
A class annotated with @RestController is capable of handling HTTP requests and automatically serializing the response to the requested format (JSON/XML). The return value of the methods is directly sent as the response body.
Here's an example of a REST controller class using @RestController:
@RestController
public class MyRestController {
@RequestMapping("/api/hello")
public String hello() {
return "Hello, World!"; // returns the response body directly
}
}
Key Differences
Response Handling: With
@Controller, the return value of a method is resolved by a view resolver to render the response. In contrast,@RestControllerdirectly serializes the return value and sends it as the response body.Content Negotiation:
@Controllerallows for content negotiation based on theAcceptheader, which means it can return different views based on the client's requested format.@RestControlleralways returns the response in the format requested by the client (JSON/XML).Convenience:
@RestControlleris a convenient choice when building RESTful APIs, as it eliminates the need for additional annotations like@ResponseBody.
Conclusion
In summary, the choice between @Controller and @RestController depends on the type of application you are building. If you are developing a traditional web application that requires view resolution, use @Controller. On the other hand, if you are building a RESTful API that returns JSON or XML responses directly, @RestController is the way to go.
Understanding the differences between these annotations will help you make the right choice and build efficient and scalable Spring applications.
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