请用JavaSpirt技术帮我写一份校园快递代取快递的小程序，分别包含用户模块，任务模块，支付模块，消息模块。

好的，让我来为您提供一份基于Java Spring技术的校园快递代取小程序的代码示例：

1. 用户模块：

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String password;
    private String email;
    private String phone;
    // getters/setters omitted for brevity
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    User findByUsername(String username);
}

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

    public User findByUsername(String username) {
        return userRepository.findByUsername(username);
    }
}

2. 任务模块：

@Entity
@Table(name = "tasks")
public class Task {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    private String description;
    private String pickupAddress;
    private String deliveryAddress;
    private Double fee;
    @ManyToOne(fetch = FetchType.LAZY)
    private User owner;
    private TaskStatus status;
    // getters/setters omitted for brevity
}

public enum TaskStatus {
    OPEN, ASSIGNED, COMPLETED
}

@Repository
public interface TaskRepository extends JpaRepository<Task, Long> {
    List<Task> findByStatus(TaskStatus status);
}

@Service
public class TaskService {
    @Autowired
    private TaskRepository taskRepository;

    public List<Task> findByStatus(TaskStatus status) {
        return taskRepository.findByStatus(status);
    }
}

3. 支付模块：

@Entity
@Table(name = "payments")
public class Payment {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private Double amount;
    private String currency;
    private String description;
    private PaymentStatus status;
    @ManyToOne(fetch = FetchType.LAZY)
    private User user;
    @ManyToOne(fetch = FetchType.LAZY)
    private Task task;
    // getters/setters omitted for brevity
}

public enum PaymentStatus {
    PENDING, COMPLETED, FAILED
}

@Repository
public interface PaymentRepository extends JpaRepository<Payment, Long> {
    List<Payment> findByUser(User user);
}

@Service
public class PaymentService {
    @Autowired
    private PaymentRepository paymentRepository;

    public List<Payment> findByUser(User user) {
        return paymentRepository.findByUser(user);
    }

    public Payment createPayment(Double amount, String currency, String description, User user, Task task) {
        Payment payment = new Payment();
        payment.setAmount(amount);
        payment.setCurrency(currency);
        payment.setDescription(description);
        payment.setUser(user);
        payment.setTask(task);
        payment.setStatus(PaymentStatus.PENDING);
        return paymentRepository.save(payment);
    }

    public Payment completePayment(Long paymentId) {
        Payment payment = paymentRepository.findById(paymentId).orElseThrow(() -> new PaymentNotFoundException(paymentId));
        payment.setStatus(PaymentStatus.COMPLETED);
        return paymentRepository.save(payment);
    }
}

4. 消息模块：

@Entity
@Table(name = "messages")
public class Message {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String text;
    private LocalDateTime sentAt;
    @ManyToOne(fetch = FetchType.LAZY)
    private User sender;
    @ManyToOne(fetch = FetchType.LAZY)
    private User recipient;
    @ManyToOne(fetch = FetchType.LAZY)
    private Task task;
    // getters/setters omitted for brevity
}

@Repository
public interface MessageRepository extends JpaRepository<Message, Long> {
    List<Message> findByTask(Task task);
}

@Service
public class MessageService {
    @Autowired
    private MessageRepository messageRepository;

    public List<Message> findByTask(Task task) {
        return messageRepository.findByTask(task);
    }

    public Message createMessage(String text, User sender, User recipient, Task task) {
        Message message = new Message();
        message.setText(text);
        message.setSentAt(LocalDateTime.now());
        message.setSender(sender);
        message.setRecipient(recipient);
        message.setTask(task);
        return messageRepository.save(message);
    }
}

这是一个简单的示例，您可以根据自己的需求进行修改和扩展。同时，您还需要编写控制器和视图层来实现用户界面和交互。