ResponseEntity for full response control in Spring Boot - Mini Project: Build & Apply

ResponseEntity for full response control

📖 Scenario: You are building a simple Spring Boot REST API that returns user information. You want to control the full HTTP response including status code, headers, and body.

🎯 Goal: Create a Spring Boot controller method that returns a ResponseEntity with a JSON body, custom HTTP status, and a custom header.

📋 What You'll Learn

Create a User class with fields id and name

Create a controller method that returns a ResponseEntity<User>

Set HTTP status to 200 OK

Add a custom header X-Custom-Header with value CustomValue

Return a User object with id=1 and name='Alice'

💡 Why This Matters

🌍 Real World

In real APIs, controlling the full HTTP response lets you set status codes and headers needed by clients or intermediaries.

💼 Career

Understanding ResponseEntity is essential for backend developers working with Spring Boot to build robust REST APIs.

1

Create the User class

Create a public class called User with two private fields: int id and String name. Add a constructor that takes int id and String name and sets the fields.

Spring Boot

// Your code here

Need a hint?

Define a simple Java class with fields and a constructor.

2

Create the controller class and method

Create a Spring REST controller class called UserController annotated with @RestController. Inside it, create a method called getUser annotated with @GetMapping("/user") that returns ResponseEntity<User>.

Spring Boot

public class User {
    private int id;
    private String name;

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

// Your code here

Need a hint?

Use Spring annotations to create a REST controller and a GET endpoint.

3

Create the User object and ResponseEntity

Inside the getUser method, create a User object with id = 1 and name = "Alice". Then return a ResponseEntity with this user as the body, HTTP status 200 OK, and a custom header X-Custom-Header with value CustomValue.

Spring Boot

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

public class User {
    private int id;
    private String name;

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

@RestController
public class UserController {

    @GetMapping("/user")
    public ResponseEntity getUser() {
        // Your code here
    }
}

Need a hint?

Create the user object, headers, and return a ResponseEntity with all parts.

4

Add class-level request mapping

Add the annotation @RequestMapping("/api") to the UserController class to prefix all endpoints with /api.

Spring Boot

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;
import org.springframework.web.bind.annotation.RequestMapping;

public class User {
    private int id;
    private String name;

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

@RestController
// Your code here
public class UserController {

    @GetMapping("/user")
    public ResponseEntity getUser() {
        User user = new User(1, "Alice");
        HttpHeaders headers = new HttpHeaders();
        headers.add("X-Custom-Header", "CustomValue");
        return new ResponseEntity(user, headers, HttpStatus.OK);
    }
}

Need a hint?

Add the @RequestMapping annotation above the controller class.