C# C语言中的类设计结构#

实体类：

public class Customer {
        public int CustomerId { get; set; }
        public string Name { get; set; }
}

public class Invoice {
        public int InvoiceId { get; set; }
        public int CustomerId { get; set; }
        public string InvoiceNo { get; set; }
}

接口：

public interface ICustomerService {
    Customer GetCustomerById(int customerId);
    void DeleteCustomer(int customerId);
}

public interface IInvoiceService {
    Invoice GetInvoiceById(int invoiceId);
    void DeleteInvoice(int invoiceId);
    List<Invoice> GetAllInvoiceByCustomer(int customerId);
    Customer GetInvoiceCustomer(int invoiceId);
}

因为当我为“CustomerService”创建新实例时，“CustomerService”将为“InvoiceService”创建新实例，“InvoiceServer”也将为“CustomerServer”创建新实例

1） 我应该将所有方法设置为静态吗？

2） “InvoiceService”将从“CustomerService”调用方法，“CustomerService”也将从“InvoiceSercie”调用方法。我怎样写这些课程？如果我把所有的方法都设置为静态，问题就会解决，但我想这不是一个好的解决方案

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多谢各位

您必须选择其中一个类来传递自身作为对另一个类的引用。假设是客户服务：

public class CustomerService : ICustomerService {

  private readonly IInvoiceService _invoiceService = new InvoiceService(this);

  ...
}

public class InvoiceService : IInvoiceService {

  private readonly ICustomerService _customerService;

  public class InvoiceService(ICustomerService customerService) {
    _customerService = customerService;
  }

}

现在循环被打破了

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另一种选择是使用依赖注入框架，如StructureMap或Ninject。

一般来说，我建议减少类之间的耦合。每个类应该做一件事（Customer和Invoice），然后创建第三个类，该类使用这两种方法。例如，您可以创建一个名为“CustomerInvoicer”的类，该类接受其构造函数中的两个接口，并将方法“GetInvoiceCustomer”移动到该新类中。根据我的经验，从长远来看，这将使它更易于维护，因为每个类都有一个单独的职责，而最终用户只需要使用一个主类（可能有更高级的逻辑）

另外，我建议使用这种方法的依赖项注入库

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public class CustomerService : ICustomerService {

  private readonly IInvoiceService _invoiceService = new InvoiceService(this);

  ...
}

public class InvoiceService : IInvoiceService {

  private readonly ICustomerService _customerService;

  public class InvoiceService(ICustomerService customerService) {
    _customerService = customerService;
  }

}

public class CustomerInvoicer {

    private readonly ICustomerService _customerService;
    private readonly IInvoiceService _invoiceService;

    public CustomerInvoicer(ICustomerService cust, IInvoiceService inv) {
        _invoiceService = inv;
        _customerService = cust;
    }


    public Customer GetInvoiceCustomer(int invoiceId) {
        Invoice invoice = _invoiceService.GetInvoiceById(invoiceId);
        return _customerService.GetCustomerById(invoice.CustomerId);
    }
}