领域驱动开发的示例代码

// 业务领域层
public class Customer {
    private String id;
    private String name;
    private String email;

    // 构造函数、getter和setter方法

    @Override
    public String toString() {
        return "Customer{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

public class CustomerService {
    private Repository<Customer> customerRepository;

    public CustomerService(Repository<Customer> customerRepository) {
        this.customerRepository = customerRepository;
    }

    public Customer findCustomerById(String id) {
        return customerRepository.findById(id).orElse(null);
    }

    public Customer createCustomer(Customer customer) {
        return customerRepository.save(customer);
    }
}

// 应用服务层
public class CustomerApplicationService {
    private CustomerRepository customerRepository;
    private CustomerService customerService;

    public CustomerApplicationService(CustomerRepository customerRepository, CustomerService customerService) {
        this.customerRepository = customerRepository;
        this.customerService = customerService;
    }

    public Customer findCustomerById(String id) {
        return customerRepository.findById(id).orElse(null);
    }

    public Customer createCustomer(String name, String email) {
        Customer customer = new Customer();
        customer.setName(name);
        customer.setEmail(email);
        return customerService.createCustomer(customer);
    }
}

// 基础设施层
@Repository
public class InMemoryCustomerRepository implements CustomerRepository {
    private List<Customer> customers;

    public InMemoryCustomerRepository() {
        customers = new ArrayList<>();
    }

    @Override
    public Optional<Customer> findById(String id) {
        return Optional.ofNullable(customers.stream()
                .filter(customer -> customer.getId().equals(id))
                .findFirst()
                .orElse(null));
    }

    @Override
    public Customer save(Customer customer) {
        customers.add(customer);
        return customer;
    }
}

// 技术框架层
public interface CustomerRepository {
    Optional<Customer> findById(String id);
    Customer save(Customer customer);
}

// 用户界面层
@Component
public class CustomerController {
    private CustomerApplicationService customerApplicationService;

    @Autowired
    public CustomerController(CustomerApplicationService customerApplicationService) {
        this.customerApplicationService = customerApplicationService;
    }

    @GetMapping("/customer/{id}")
    public String findCustomerById(@PathVariable String id, Model model) {
        Customer customer = customerApplicationService.findCustomerById(id);
        model.addAttribute("customer", customer);
        return "customer-details";
    }

    @PostMapping("/customer")
    public String createCustomer(@RequestParam String name, @RequestParam String email, Model model) {
        Customer customer = customerApplicationService.createCustomer(name, email);
        model.addAttribute("customer", customer);
        return "customer-created";
    }
}

这是一个简单的领域驱动开发示例代码，包含业务领域层的Customer实体和CustomerService服务，应用服务层的CustomerApplicationService，基础设施层的InMemoryCustomerRepository，技术框架层的CustomerRepository接口，以及用户界面层的CustomerController控制器。