ResponseBody

ResponseEntity represents an HTTP response, including headers, body, and status in a spring restful API. While @ResponseBody puts the return value into the body of the response of API, ResponseEntity also allows us to add headers and status code as well.

Prerequisite :

Let’s take a Java Entity Model Class called “Dependant” to be used in this example.

@Entity
@Table(name = "Dependant")
public class Dependant implements Serializable {

    @Id
    private int deptid;

    @Column(name="firstname")
    private String firstname;

    @Column(name="lastname")
    private String lastname;

    // getter, setter methods ...
}

1. ResponseEntity

Example

Let’s create a simple REST API which returns Dependant class object which we made above, wrapped inside the ResponseEntity.

@GetMapping("/dependant/id/{id}")
public ResponseEntity<Dependant> getDependantbyId(@PathVariable int id){
        
    Dependant dept = new Dependant();
    dept = dependantRepository.findBydeptid(id);
   
    HttpHeaders headers = new HttpHeaders();
    headers.add("Custom-Header", "foo - Department");

    return ResponseEntity.status(HttpStatus.OK).headers(headers).body(dept);
}

We give ResponseEntity a custom status code, headers, and a body.

OUTPUT

Status : 200 OK

Custom-Header →foo - Department
Content-Type →application/json;charset=UTF-8
Transfer-Encoding →chunked
Date →Tue, 25 Feb 2020 07:48:58 GMT

and body as shown below

{
    "deptid": 1,
    "firstname": "Donald",
    "lastname": "T",
}

2. @ResponseBody

Example

In this example we try to achieve the same as as ResponseEntity but @ResponseBody only returns the body, in this case only the Dependant class object.

@GetMapping("/dependant/id/{id}")
@ResponseBody
public Dependant getDependant2byId(@PathVariable int id){

    Dependant dept = new Dependant();
    dept = dependantRepository.findBydeptid(id);
    
    return dept;
}

With @ResponseBody, only the body is returned. The headers and status code are provided by Spring.

3. @ResponseStatus

@ResponseStatus marks a method or exception class with the status code and reason message that should be returned. The status code is applied to the HTTP response when the handler method is invoked, or whenever the specified exception is thrown.
It overrides status information set by other means, like ResponseEntity or redirect.

Example : Custom Exceptions

@GetMapping("/dependant/id/{id}")
@ResponseBody
public Dependant getDependantbyId(@PathVariable int id){

	if(id>10){
		throw new MyCustomException("the id is not in range");
	}
	Dependant dept = new Dependant();
	dept = dependantRepository.findBydeptid(id);

	return dept;
}
	
@ResponseStatus(value = HttpStatus.NOT_FOUND, reason = "No such dependant with this id")
public class MyCustomException extends RuntimeException {

    public MyCustomException(String message){
        super(message);
    }
}

Summary

In this article, we looked into ResponseEntity, ResponseBody and ResponseStatus functionalities/annotations. We learnt it by simple examples.
Please let us know if you have any questions or concerns related to the topic in the comments section below.
Hope you liked it !

---