Content type negotiation in Spring Boot - Mini Project: Build & Apply

Content Type Negotiation in Spring Boot

📖 Scenario: You are building a simple Spring Boot REST API that returns user information. Different clients may want the data in JSON or XML format.Content type negotiation allows the server to send the response in the format the client prefers.

🎯 Goal: Create a Spring Boot controller that returns user data and supports content type negotiation for JSON and XML.

📋 What You'll Learn

Create a User class with id and name fields

Create a REST controller with a GET endpoint /user

Configure the controller to return the User object

Enable content type negotiation so the response can be JSON or XML based on client request

💡 Why This Matters

🌍 Real World

APIs often need to serve different clients that prefer different data formats like JSON or XML. Content type negotiation makes your API flexible and user-friendly.

💼 Career

Understanding content type negotiation is essential for backend developers building RESTful services that interact with diverse clients.

1

Create the User class

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

Spring Boot

// Your code here

Need a hint?

Think of User as a simple box holding an id and a name. You need a constructor to put values inside.

2

Create the REST controller

Create a class called UserController annotated with @RestController. Add a method getUser annotated with @GetMapping("/user") that returns a new User object with id 1 and name "Alice".

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 @RestController to make the class a REST API controller. The @GetMapping("/user") marks the method as the GET endpoint.

3

Enable content type negotiation

Add the @RequestMapping(produces = {"application/json", "application/xml"}) annotation to the UserController class to allow the endpoint to produce both JSON and XML responses.

Spring Boot

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 User getUser() {
        return new User(1, "Alice");
    }
}

Need a hint?

The @RequestMapping annotation with produces tells Spring Boot to support these response types.

4

Add XML support dependency

Add the spring-boot-starter-web and jackson-dataformat-xml dependencies to your pom.xml or build.gradle to enable XML serialization support in Spring Boot.

Spring Boot

Need a hint?

Spring Boot needs the XML data format library to convert objects to XML.