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Domain、BO、BIZ 三层的协作关系

news 2025/9/22 17:52:48

电商、银行、医疗三个领域的经典分层案例，展示 domain、bo、biz 三层的协作关系：

‌案例1：电商订单系统‌

‌1. Domain层（领域模型）

// domain/entity/Order.java
public class Order {private String orderId;private List<OrderItem> items;private OrderStatus status;// 领域行为：计算订单总价public BigDecimal calculateTotal() {return items.stream().map(item -> item.getPrice().multiply(item.getQuantity())).reduce(BigDecimal.ZERO, BigDecimal::add);}
}

‌2. BO层（业务对象）

// bo/OrderBO.java
public class OrderBO {private Order order;private InventoryService inventoryService;// 业务逻辑：校验库存并预留public void reserveInventory() {if (!inventoryService.checkStock(order.getItems())) {throw new BusinessException("库存不足");}}
}

‌3. Biz层（业务服务）

// biz/OrderService.java
public class OrderService {public void createOrder(OrderCreateDTO dto) {OrderBO orderBO = new OrderBO(convertToOrder(dto));orderBO.reserveInventory();  // 调用BO处理业务规则paymentService.charge(orderBO.getOrder());  // 协调第三方支付}
}

‌案例2：银行转账系统‌

‌1. Domain层

// domain/entity/Account.java
public class Account {private String accountId;private BigDecimal balance;// 领域行为：扣款public void debit(BigDecimal amount) {if (balance.compareTo(amount) < 0) {throw new InsufficientBalanceException();}this.balance = balance.subtract(amount);}
}

‌2. BO层

// bo/TransferBO.java
public class TransferBO {private Account source;private Account target;// 业务逻辑：执行双账户原子操作public void executeTransfer(BigDecimal amount) {source.debit(amount);target.credit(amount);  // 省略credit方法实现}
}

‌3. Biz层

// biz/TransferService.java
public class TransferService {@Transactionalpublic void transfer(TransferRequestDTO dto) {TransferBO transferBO = new TransferBO(accountRepository.findById(dto.getSourceAccountId()),accountRepository.findById(dto.getTargetAccountId()));transferBO.executeTransfer(dto.getAmount());  // 调用BOauditLog.logTransfer(dto);  // 协调审计日志}
}

‌案例3：医院预约系统‌

‌1. Domain层

// domain/entity/Appointment.java
public class Appointment {private Doctor doctor;private Patient patient;private LocalDateTime time;// 领域规则：校验预约时间有效性public boolean isValidTime() {return time.getHour() >= 9 && time.getHour() <= 17;}
}

2. BO层

// bo/AppointmentBO.java
public class AppointmentBO {private Appointment appointment;private ScheduleService scheduleService;// 业务逻辑：检查医生排班冲突public void checkConflict() {if (!scheduleService.isAvailable(appointment.getDoctor(), appointment.getTime())) {throw new ConflictException("医生该时段已排班");}}
}

‌3. Biz层

// biz/AppointmentService.java
public class AppointmentService {public void bookAppointment(AppointmentDTO dto) {AppointmentBO appointmentBO = new AppointmentBO(convertToEntity(dto));appointmentBO.checkConflict();  // 调用BO校验notificationService.sendConfirmation(appointmentBO.getAppointment());  // 协调通知}
}