Java-based Smart Parking System

Building a Java-based Smart Parking System involves creating a system that allows users to find, reserve, and pay for parking spots in real-time. Below is a step-by-step guide to building such a system, including the key components, design considerations, and example code snippets.

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1. Requirements Analysis

Before starting, define the requirements for the system:

• User Roles: Admin (manage parking spots) and User (find and reserve parking spots).
• Parking Spot Management: Add, update, delete, and view parking spots.
• Parking Reservation: Allow users to reserve parking spots.
• Real-Time Availability: Show real-time availability of parking spots.
• Payment Integration: Integrate a payment gateway for parking fees.
• Security: Secure access to the system for authenticated users.

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2. System Design

Modules

1. User Management

• Register and authenticate users.

1. Parking Spot Management

• Add, update, delete, and view parking spots.

1. Parking Reservation

• Allow users to reserve parking spots.

1. Real-Time Availability

• Show real-time availability of parking spots.

1. Payment Integration

• Process payments for parking reservations.

1. Security

• Secure access to the system for authenticated users.

Database Design

• User Table: user_id, username, password, role
• Parking Spot Table: spot_id, location, status, reserved_by, reservation_time
• Reservation Table: reservation_id, user_id, spot_id, start_time, end_time, status

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3. Technology Stack

• Backend: Java (Spring Boot)
• Frontend: Thymeleaf (for simplicity) or Angular/React (for advanced UI)
• Database: MySQL or H2 (for testing)
• Build Tool: Maven or Gradle
• Security: Spring Security for authentication and authorization
• Payment Gateway: Integrate with a payment gateway like Stripe or PayPal

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4. Implementation

Step 1: Set Up the Project

Create a Spring Boot project using Spring Initializr with the following dependencies:

• Spring Web
• Spring Data JPA
• Spring Security
• Thymeleaf (for UI)
• MySQL Driver (or H2 for testing)

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Step 2: Define Entities

Create Java classes for the database tables.

User.java

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long userId;
    private String username;
    private String password;
    private String role; // "ADMIN" or "USER"

    // Getters and Setters
}

ParkingSpot.java

@Entity
public class ParkingSpot {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long spotId;
    private String location;
    private String status; // "AVAILABLE", "RESERVED"
    private Long reservedBy;
    private LocalDateTime reservationTime;

    // Getters and Setters
}

Reservation.java

@Entity
public class Reservation {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long reservationId;
    private Long userId;
    private Long spotId;
    private LocalDateTime startTime;
    private LocalDateTime endTime;
    private String status; // "ACTIVE", "COMPLETED"

    // Getters and Setters
}

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Step 3: Create Repositories

Use Spring Data JPA to create repositories for database operations.

UserRepository.java

public interface UserRepository extends JpaRepository<User, Long> {
    Optional<User> findByUsername(String username); // For authentication
}

ParkingSpotRepository.java

public interface ParkingSpotRepository extends JpaRepository<ParkingSpot, Long> {
    List<ParkingSpot> findByStatus(String status); // For available spots
}

ReservationRepository.java

public interface ReservationRepository extends JpaRepository<Reservation, Long> {
    List<Reservation> findByUserId(Long userId); // For user's reservations
}

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Step 4: Implement Services

Create service classes to handle business logic.

UserService.java

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public void registerUser(User user) {
        userRepository.save(user);
    }

    public boolean authenticateUser(String username, String password) {
        Optional<User> user = userRepository.findByUsername(username);
        return user.isPresent() && user.get().getPassword().equals(password);
    }
}

ParkingSpotService.java

@Service
public class ParkingSpotService {
    @Autowired
    private ParkingSpotRepository parkingSpotRepository;

    public List<ParkingSpot> getAvailableSpots() {
        return parkingSpotRepository.findByStatus("AVAILABLE");
    }

    public void reserveSpot(Long spotId, Long userId) {
        ParkingSpot spot = parkingSpotRepository.findById(spotId).orElseThrow();
        spot.setStatus("RESERVED");
        spot.setReservedBy(userId);
        spot.setReservationTime(LocalDateTime.now());
        parkingSpotRepository.save(spot);
    }

    public void releaseSpot(Long spotId) {
        ParkingSpot spot = parkingSpotRepository.findById(spotId).orElseThrow();
        spot.setStatus("AVAILABLE");
        spot.setReservedBy(null);
        spot.setReservationTime(null);
        parkingSpotRepository.save(spot);
    }
}

ReservationService.java

@Service
public class ReservationService {
    @Autowired
    private ReservationRepository reservationRepository;

    public void createReservation(Long userId, Long spotId, LocalDateTime startTime, LocalDateTime endTime) {
        Reservation reservation = new Reservation();
        reservation.setUserId(userId);
        reservation.setSpotId(spotId);
        reservation.setStartTime(startTime);
        reservation.setEndTime(endTime);
        reservation.setStatus("ACTIVE");
        reservationRepository.save(reservation);
    }

    public void completeReservation(Long reservationId) {
        Reservation reservation = reservationRepository.findById(reservationId).orElseThrow();
        reservation.setStatus("COMPLETED");
        reservationRepository.save(reservation);
    }

    public List<Reservation> getUserReservations(Long userId) {
        return reservationRepository.findByUserId(userId);
    }
}

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Step 5: Create Controllers

Create controllers to handle HTTP requests.

UserController.java

@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping("/register")
    public void registerUser(@RequestBody User user) {
        userService.registerUser(user);
    }

    @PostMapping("/authenticate")
    public boolean authenticateUser(@RequestParam String username, @RequestParam String password) {
        return userService.authenticateUser(username, password);
    }
}

ParkingSpotController.java

@RestController
@RequestMapping("/parking-spots")
public class ParkingSpotController {
    @Autowired
    private ParkingSpotService parkingSpotService;

    @GetMapping("/available")
    public List<ParkingSpot> getAvailableSpots() {
        return parkingSpotService.getAvailableSpots();
    }

    @PostMapping("/reserve")
    public void reserveSpot(@RequestParam Long spotId, @RequestParam Long userId) {
        parkingSpotService.reserveSpot(spotId, userId);
    }

    @PostMapping("/release")
    public void releaseSpot(@RequestParam Long spotId) {
        parkingSpotService.releaseSpot(spotId);
    }
}

ReservationController.java

@RestController
@RequestMapping("/reservations")
public class ReservationController {
    @Autowired
    private ReservationService reservationService;

    @PostMapping
    public void createReservation(@RequestParam Long userId, @RequestParam Long spotId,
                                  @RequestParam LocalDateTime startTime, @RequestParam LocalDateTime endTime) {
        reservationService.createReservation(userId, spotId, startTime, endTime);
    }

    @PostMapping("/complete")
    public void completeReservation(@RequestParam Long reservationId) {
        reservationService.completeReservation(reservationId);
    }

    @GetMapping("/{userId}")
    public List<Reservation> getUserReservations(@PathVariable Long userId) {
        return reservationService.getUserReservations(userId);
    }
}

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Step 6: Implement Security

Use Spring Security to secure the application.

SecurityConfig.java

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Autowired
    private UserRepository userRepository;

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(username -> userRepository.findByUsername(username)
                .orElseThrow(() -> new UsernameNotFoundException("User not found")));
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable()
            .authorizeRequests()
            .antMatchers("/users/**", "/parking-spots/**", "/reservations/**").authenticated()
            .anyRequest().permitAll()
            .and()
            .httpBasic();
    }
}

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Step 7: Frontend (Optional)

Use Thymeleaf or a frontend framework like Angular/React to create a user interface for the system.

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5. Testing

• Use JUnit and Mockito for unit testing.
• Test the application using Postman or Swagger for API testing.

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6. Deployment

• Package the application as a JAR/WAR file and deploy it to a server (e.g., Tomcat).
• Use Docker for containerization and Kubernetes for orchestration (optional).

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Example Use Cases

1. User Registration

• User registers with details like username and password.

1. Parking Spot Reservation

• User reserves a parking spot.

1. Parking Spot Release

• User releases a reserved parking spot.

1. Reservation Management

• User views and completes their reservations.

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