🔐 Spring Boot JWT Authentication API

Production-ready REST API built with Spring Boot implementing a complete JWT-based authentication and authorization system, including:

• ✅ JWT Login
• ✅ Access Token & Refresh Token
• ✅ Role-based Authorization
• ✅ Docker + MySQL
• ✅ Global Exception Handling (@ControllerAdvice)
• ✅ SecurityFilterChain Configuration
• ✅ Token Refresh Flow
• ✅ Clean User → UserDetails Mapping

🚀 Tech Stack

• Java 17+
• Spring Boot 3+
• Spring Security
• JWT (JJWT)
• MySQL
• Docker & Docker Compose
• Lombok
• gradle

🔑 JWT Authentication

📌 Token Types

| Token | Lifetime | Purpose | | ------------- | ------------- | -------------------------- | | Access Token | 10–15 minutes | Access protected endpoints | | Refresh Token | 7–30 days | Generate new access tokens |

🔓 Authentication Endpoints

✅ Login

POST /api/auth/login

Response:

{
  "accessToken": "...",
  "refreshToken": "..."
}

✅ Refresh Token

POST /api/auth/refresh

Request Body:

{
  "refreshToken": "..."
}

Response:

{
  "accessToken": "new-access-token"
}

🧠 Security Architecture

🔐 JwtService

Service responsible for:

• Generating Access Tokens
• Generating Refresh Tokens
• Extracting username from token
• Validating token signature and expiration

🧩 UserDetailsFactory

Utility class that converts the User entity into a UserDetails instance:

public class UserDetailsFactory {

    public static UserDetails create(User user) {
        List<GrantedAuthority> authorities = user.getRoles().stream()
                .map(role -> new SimpleGrantedAuthority(role.getName()))
                .toList();

        return new org.springframework.security.core.userdetails.User(
                user.getUsername(),
                user.getPassword(),
                user.isEnabled(),
                true,
                true,
                true,
                authorities
        );
    }
}

🔁 Refresh Token Flow

1. User logs in
2. Receives Access Token + Refresh Token
3. Access Token expires
4. Frontend sends Refresh Token
5. Backend validates Refresh Token
6. New Access Token is generated ✅

🧱 Role-Based Authorization

• Roles are mapped to GrantedAuthority
• Roles are included as claims inside JWT
• Access rules defined using:

.hasAuthority("ADMIN")

🐳 Docker

The project uses:

• MySQL container
• Backend connected via application.properties

⚠️ Global Exception Handling

Implemented using @ControllerAdvice for:

• Validation errors
• Authentication errors
• Resource not found
• Custom business exceptions

✅ Best Practices Applied

• Layered architecture
• DTOs for requests and responses
• Stateless security
• Decoupled role management
• Token expiration control
• Entity to UserDetails mapping

✅ Project Status

✔️ Production-ready ✔️ Complete security layer ✔️ Clean architecture ✔️ Ready for deployment

👨‍💻 Author

Developed as part of an advanced backend learning process using Spring Boot.

🔥 This project follows real-world backend security standards and practices.