@RequestBody and @ResponseBody annotations in Spring

Question

Can someone explain the @RequestBody and @ResponseBody annotations in Spring 3? What are they for? Any examples would be great.

Markle

Answer 1

There is a whole Section in the docs called 16.3.3.4 Mapping the request body with the @RequestBody annotation. And one called 16.3.3.5 Mapping the response body with the @ResponseBody annotation. I suggest you consult those sections. Also relevant: @RequestBody javadocs, @ResponseBody javadocs

Usage examples would be something like this:

Using a JavaScript-library like JQuery, you would post a JSON-Object like this:

{ "firstName" : "Elmer", "lastName" : "Fudd" }

Your controller method would look like this:

// controller
@ResponseBody @RequestMapping("/description")
public Description getDescription(@RequestBody UserStats stats){
    return new Description(stats.getFirstName() + " " + stats.getLastname() + " hates wacky wabbits");
}

// domain / value objects
public class UserStats{
    private String firstName;
    private String lastName;
    // + getters, setters
}
public class Description{
    private String description;
    // + getters, setters, constructor
}

Now if you have Jackson on your classpath (and have an <mvc:annotation-driven> setup), Spring would convert the incoming JSON to a UserStats object from the post body (because you added the @RequestBody annotation) and it would serialize the returned object to JSON (because you added the @ResponseBody annotation). So the Browser / Client would see this JSON result:

{ "description" : "Elmer Fudd hates wacky wabbits" }

See this previous answer of mine for a complete working example: https://mcmap.net/q/151668/-jquery-spring-mvc-requestbody-and-json-making-it-work-together

Note: RequestBody / ResponseBody is of course not limited to JSON, both can handle multiple formats, including plain text and XML, but JSON is probably the most used format.

---

Update

Ever since Spring 4.x, you usually won't use @ResponseBody on method level, but rather @RestController on class level, with the same effect.

Here is a quote from the official Spring MVC documentation:

@RestController is a composed annotation that is itself meta-annotated with @Controller and @ResponseBody to indicate a controller whose every method inherits the type-level @ResponseBody annotation and, therefore, writes directly to the response body versus view resolution and rendering with an HTML template.

Dordrecht

In your linked answer, you used the @ResponseBody annotation on the parameter, not the method. I get errors trying to put it on the method, so I'm assuming your other answer is correct. I think you should have getDescription(@RequestBody UserStats stats) above. – Garofalo

@Garofalo no, @RequestBody is on the parameter, @ResponseBody is on the method. important difference! – Dordrecht

@SeanPatrickFloyd Sorry, I didn't mean to mention @ResponseBody at all. As you just said, @RequestBody goes on the parameter, right? But in the above answer, you have it on the method. – Garofalo

@SeanPatrickFloyd @RequestBody is actually still required, @ResponseBody is implicit when using @RestController. Pls correct your answer, it has too many upvotes to be false! – Backstroke

@SumitJain to be fair: this answer was around before @RestController and was changed when it was introduced – Dordrecht

And yes, I had confused RequestBody and ResponseBody. Fixed. – Dordrecht

@PSyLoCKe you need some serialization provider. Either Jackson or JAXB are picked up automatically, if present. Others need configuration. But Spring itself doesn't serialize anything. – Dordrecht

Answer 2

@RequestBody : Annotation indicating a method parameter should be bound to the body of the HTTP request.

For example:

@RequestMapping(path = "/something", method = RequestMethod.PUT)
public void handle(@RequestBody String body, Writer writer) throws IOException {
    writer.write(body);
}

@ResponseBody annotation can be put on a method and indicates that the return type should be written straight to the HTTP response body (and not placed in a Model, or interpreted as a view name).

For example:

@RequestMapping(path = "/something", method = RequestMethod.PUT)
public  @ResponseBody String helloWorld() {
    return "Hello World";
}  

Alternatively, we can use @RestController annotation in place of @Controller annotation. This will remove the need to using @ResponseBody.

for more details

Lizettelizotte

Answer 3

Below is an example of a method in a Java controller.

@RequestMapping(method = RequestMethod.POST)
@ResponseBody
public HttpStatus something(@RequestBody MyModel myModel) 
{
    return HttpStatus.OK;
}

By using @RequestBody annotation you will get your values mapped with the model you created in your system for handling any specific call. While by using @ResponseBody you can send anything back to the place from where the request was generated. Both things will be mapped easily without writing any custom parser etc.

Koffler

Answer 4

@RestController is a composed annotation that is itself meta-annotated with @Controller and @ResponseBody to indicate a controller whose every method inherits the type-level @ResponseBody annotation and, therefore, writes directly to the response body versus view resolution and rendering with an HTML template So instead of marking your class as @Controller use @RestController instead and remove the @requestbody annotation from you class

heres an example: @RestController

public class MomController {

    @RequestMapping("/sugar") // maped to the url /sugar
    public String addSugar() {
        return "here is your sugar";
    }
}

Silvertongued

Answer 5

package com.programmingfree.springshop.controller;

import java.util.List;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.programmingfree.springshop.dao.UserShop;
import com.programmingfree.springshop.domain.User;


@RestController
@RequestMapping("/shop/user")
public class SpringShopController {

 UserShop userShop=new UserShop();

 @RequestMapping(value = "/{id}", method = RequestMethod.GET,headers="Accept=application/json")
 public User getUser(@PathVariable int id) {
  User user=userShop.getUserById(id);
  return user;
 }


 @RequestMapping(method = RequestMethod.GET,headers="Accept=application/json")
 public List<User> getAllUsers() {
  List<User> users=userShop.getAllUsers();
  return users;
 }


}

In the above example they going to display all user and particular id details now I want to use both id and name,

1) localhost:8093/plejson/shop/user <---this link will display all user details
2) localhost:8093/plejson/shop/user/11 <----if i use 11 in link means, it will display particular user 11 details

now I want to use both id and name

localhost:8093/plejson/shop/user/11/raju <-----------------like this it means we can use any one in this please help me out.....

Intestine

Please correct formatting of the answer and code sample. – Intimidate

Please describe how this code helps the questioner. Thank you. – Sesquicarbonate