In recent years, with the increasing popularity of microservices architecture and SPA (Single Page Application), it has become very important to find security measures for web applications. In this article, we will explain in detail how to implement login/logout functionality using JWT (JSON Web Token) and a domain that uses refresh tokens with Spring Boot.
Table of Contents
- 1. Introduction
- 2. What is Spring Boot?
- 3. What is JWT?
- 4. Setting Up the Development Environment
- 5. Implementing Login/Logout Functionality
- 6. Implementing Refresh Token
- 7. Conclusion
1. Introduction
User authentication and authorization are significant issues in modern web applications. Several technologies exist to address these issues, but JWT is one of the most widely used methods. In this course, you will learn how to build user login and logout functionalities using Spring Boot, as well as how to implement an authentication mechanism using JWT and refresh tokens.
2. What is Spring Boot?
Spring Boot is an extension of the Spring framework that provides convenient tools for developing Spring-based applications easily. It allows implementation without initial settings or complex XML configurations, providing pre-configured features that developers frequently use with simple annotations.
The main features of Spring Boot include:
- Embedded Server: It includes web servers such as Tomcat and Jetty, allowing you to run without separate server installations.
- Automatic Configuration: It automatically configures necessary settings based on included libraries and bean configurations in the project.
- Easy Deployment: You can easily deploy by packaging into a Jar file and it can also be conveniently used in cloud environments.
- Strong Community: It has a large community supported by rich documentation, examples, and various plugins.
3. What is JWT?
JWT (JSON Web Token) is a compact, URL-safe means of representing claims to be transferred between two parties, mainly used as a solution for authentication and authorization. Here, ‘claims’ refer to information about the user, which helps maintain a trust relationship between the server and the client.
JWT consists of three main parts:
- Header: Contains information about the type of token (typ) and hashing algorithm (alg).
- Payload: Contains information about the user and claim data, including user ID, permissions, etc.
- Signature: Combines Header and Payload, signing them with a secret key, which guarantees the integrity and authenticity of the token.
Advantages of JWT include:
- Statelessness: Since the server cannot tamper with JWT, it does not maintain state, and the client sends JWT whenever authentication is required.
- Security: Since the client holds the JWT, there is no need to query the server’s database, reducing the load on the database.
- Simplified CRUD Operations: It allows easy management of authentication info and state, and can simplify complex logic like IAM (Identity and Access Management).
4. Setting Up the Development Environment
Now, let’s set up a development environment for a project using Spring Boot. We will use the following tools:
- Java 11: Install JDK 11 or higher.
- IDE: It is recommended to use IntelliJ IDEA or Eclipse.
- Gradle or Maven: Choose Gradle or Maven for dependency management.
- Postman: Use Postman as the API testing tool.
You can set the basic settings for your project using Spring Initializr (start.spring.io). The necessary dependencies to add include:
- Spring Web
- Spring Security
- Spring Data JPA
- H2 Database (or your chosen RDBMS)
- Spring Boot DevTools (tools for development convenience)
- jjwt (Java JWT library)
After creating the project, create necessary classes such as Viewer, Controller, Service, Repository, etc. You need to add database-related settings in the `application.yml` file.
5. Implementing Login/Logout Functionality
To implement login and logout functionalities, the following components are needed:
5.1. User Entity
Create a User entity to store user information.
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String username;
private String password;
private String role;
// Getter, Setter, Constructor
}
5.2. User Repository
Create a UserRepository to perform CRUD operations on the User entity.
@Repository
public interface UserRepository extends JpaRepository {
Optional findByUsername(String username);
}
5.3. User Service
Create a UserService to implement user registration and authentication logic.
@Service
public class UserService {
@Autowired
private UserRepository userRepository;
public User register(User user) {
// Add password encryption logic and save user information here.
}
public Optional findByUsername(String username) {
return userRepository.findByUsername(username);
}
}
5.4. Security Configuration
Set up Spring Security to perform JWT authentication.
@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
// Define user authentication and security-related settings.
}
5.5. JWT Utility Class
Create a JwtUtil class responsible for generating and validating JWTs.
@Component
public class JwtUtil {
private String secretKey = "yourSecretKey"; // Secret key must be managed securely.
public String generateToken(String username) {
// Implement JWT generation logic.
}
public boolean validateToken(String token, String username) {
// JWT validation logic.
}
}
5.6. Authentication Controller
Define API endpoints to provide login and logout functionalities.
@RestController
@RequestMapping("/api/auth")
public class AuthController {
@Autowired
private UserService userService;
@Autowired
private JwtUtil jwtUtil;
@PostMapping("/login")
public ResponseEntity<String> login(@RequestBody UserCredentials userCredentials) {
// Login logic.
}
@PostMapping("/logout")
public ResponseEntity<String> logout() {
// Logout logic.
}
}
6. Implementing Refresh Token
Refresh tokens are used separately from access tokens and help users remain logged in. To implement refresh tokens, we perform the following steps:
6.1. Refresh Token Entity
Create a new entity to manage the refresh token.
@Entity
public class RefreshToken {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String token;
@ManyToOne
private User user;
private LocalDateTime expiryDate;
// Getter, Setter, Constructor
}
6.2. RefreshToken Repository
Create a repository for performing CRUD operations on refresh tokens.
@Repository
public interface RefreshTokenRepository extends JpaRepository<RefreshToken, Long> {
Optional<RefreshToken> findByToken(String token);
}
6.3. Refresh Token Service
Create a service that manages the creation of refresh tokens.
@Service
public class RefreshTokenService {
@Autowired
private RefreshTokenRepository refreshTokenRepository;
public RefreshToken createRefreshToken(User user) {
// Logic for creating a new refresh token.
}
public boolean validateRefreshToken(String token) {
// Validate the refresh token.
}
}
6.4. Refresh Token Controller
Add an API to generate a new access token using the refresh token.
@RestController
@RequestMapping("/api/auth")
public class AuthController {
@Autowired
private RefreshTokenService refreshTokenService;
@PostMapping("/refresh-token")
public ResponseEntity<String> refreshToken(@RequestBody String refreshToken) {
// Logic for generating a new access token using the refresh token.
}
}
7. Conclusion
In this tutorial, we have implemented login/logout functionalities based on JWT using Spring Boot and additionally looked at how to manage access tokens using refresh tokens. An authentication system implemented in this way can handle various client requests more securely and flexibly.
Now you will be able to implement JWT and refresh tokens in your application to provide an enhanced user experience. Furthermore, you can integrate these technologies with various additional security techniques. We look forward to future advancements!