How to Use ResponseEntity in Spring Boot for HTTP Responses

In Spring Boot, ResponseEntity is used to represent the entire HTTP response, including status code, headers, and body. You create it by returning ResponseEntity from your controller methods to customize the HTTP response sent to clients.

Syntax

The basic syntax of ResponseEntity involves specifying the response body and optionally the HTTP status and headers.

• ResponseEntity<T>: Generic type where T is the response body type.
• body(T body): Sets the response content.
• status(HttpStatus status): Sets the HTTP status code.
• headers(HttpHeaders headers): Sets HTTP headers.

java

return ResponseEntity.status(HttpStatus.OK).body("Hello World");

Example

This example shows a simple Spring Boot REST controller that returns a ResponseEntity with a JSON body, custom header, and HTTP status 200 OK.

java

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public ResponseEntity<String> greet() {
        HttpHeaders headers = new HttpHeaders();
        headers.add("Custom-Header", "MyValue");
        return ResponseEntity
                .status(HttpStatus.OK)
                .headers(headers)
                .body("{\"message\": \"Hello, Spring Boot!\"}");
    }
}

Output

HTTP/1.1 200 OK
Custom-Header: MyValue
Content-Type: application/json

{"message": "Hello, Spring Boot!"}

Common Pitfalls

Common mistakes when using ResponseEntity include:

• Returning just the body type instead of ResponseEntity when you want to customize status or headers.
• Not setting the correct HTTP status code, which can confuse API clients.
• Forgetting to set content type headers when returning JSON or other formats.

Always use ResponseEntity when you need full control over the HTTP response.

java

/* Wrong: returns only body, no status control */
@GetMapping("/wrong")
public String wrongResponse() {
    return "Hello";
}

/* Right: returns ResponseEntity with status and body */
@GetMapping("/right")
public ResponseEntity<String> rightResponse() {
    return ResponseEntity.status(HttpStatus.CREATED).body("Hello");
}

Quick Reference

Usage	Description
ResponseEntity.ok(body)	Returns 200 OK with the given body
ResponseEntity.status(HttpStatus.CREATED).body(body)	Returns 201 Created with body
ResponseEntity.status(HttpStatus.NOT_FOUND).build()	Returns 404 Not Found with no body
ResponseEntity.headers(HttpHeaders).body(body)	Returns response with custom headers and body
ResponseEntity.badRequest().body(errorMessage)	Returns 400 Bad Request with error message

Key Takeaways

Use ResponseEntity to control HTTP status, headers, and body in Spring Boot responses.

Return ResponseEntity from controller methods to customize API responses.

Use static methods like ok(), status(), badRequest() for common HTTP statuses.

Always set appropriate HTTP status codes to communicate response meaning.

Include headers when you need to send metadata or control caching.