C#中策略设计模式的正确实现方法

Question

我有一个场景，其中有多个条件，我必须以这样的方式编写代码，它应该开放扩展而不是修改，所以我采用了策略设计模式，下面是我的代码，如果我我走在正确的道路上，需要一些关于编写的代码的指导。

// Is this correct way to call it, how to apply dependency injection?
// You can find this code in the end
BaseOrderProcessing baseOrderProcessing =
    new BaseOrderProcessing(
        new BaseSubscribe(
            new SubscribeService(
                Subscribe)));  

这是实际代码：

public interface IBaseOrderProcessing
{
    void ProcessOrder();
}

public class BaseOrderProcessing : IBaseOrderProcessing
{
    private IBaseOrderProcessing _baseOrderProcessing = null;
    public BaseOrderProcessing(IBaseOrderProcessing baseOrderProcessing)
    {
        _baseOrderProcessing = baseOrderProcessing;
    }
    public virtual void ProcessOrder()
    {
        _baseOrderProcessing.ProcessOrder();
    }
}

public interface ISubscribeService
{
    SubscribeType SubscribeType { get; set; }
    void ActivateSubscribe();

    void UpgradeSubscribe();
}

// Strategy Pattern 1  => Subscribe is one of the "if" condition
public class BaseSubscribe : IBaseOrderProcessing
{
    private ISubscribeService _SubscribeService = null;
    public BaseSubscribe(ISubscribeService SubscribeService)
    {
        _SubscribeService = SubscribeService;
    }
    
    public void ProcessOrder()
    {
        if (_SubscribeService.SubscribeType == SubscribeType.ACTIVATE)
            _SubscribeService.ActivateSubscription();

        if (_SubscribeService.SubscribeType == SubscribeType.UPGRADE)
            _SubscribeService.UpgradeSubscription();
        
    }
}

// Writing another class to simplify is correct ?????
public class SubscribeService : ISubscribeService
{
    private SubscribeDetails _Subscribedetails = null;

    public SubscribeType SubscribeType { get; set; }

    public SubscribeService(SubscribeDetails Subscribedetails)
    {
        _Subscribedetails = Subscribedetails;
        SubscribeType = Subscribedetails.SubscribeType;
    }
    public void ActivateSubscription()
    {
        // Code to save the Subscribe details in the database
        Console.WriteLine(
            $"\n\nSubscribe {_Subscribedetails.SubscribeId} for " +
            $"{_Subscribedetails.SubscribeName} activated for order Id: {_Subscribedetails.OrderId}" +
            $" from {_Subscribedetails.SubscribeStartDate} to {_Subscribedetails.SubscribeEndDate}");        
    }      

    public void UpgradeSubscription()
    {
        // Code to upgrade the Subscribe details in the database
        Console.WriteLine(
            $"\n\nSubscribe {_Subscribedetails.SubscribeId} for " +
            $"{_Subscribedetails.SubscribeName} upgraded for order Id: {_Subscribedetails.OrderId}" +
            $" from {_Subscribedetails.SubscribeStartDate} to {_Subscribedetails.SubscribeEndDate}");

    }
}  

客户端代码：

// Is this correct way to call it, how to apply dependency injection?
IBaseOrderProcessing baseOrderProcessing = null;
SubscribeDetails Subscribe = new SubscribeDetails();

Subscribe.OrderId = Guid.NewGuid();
Subscribe.SubscribeId = Guid.NewGuid();
Subscribe.SubscribeName = "Amazon";
Subscribe.SubscribeStartDate = DateTime.Now;
Subscribe.SubscribeEndDate = DateTime.Now.AddDays(30);
if (option == 1)
    Subscribe.SubscribeType = SubscribeType.ACTIVATE;

if (option == 2)
    Subscribe.SubscribeType = SubscribeType.UPGRADE;

baseOrderProcessing =
    new BaseOrderProcessing(
        new BaseSubscribe(
            new SubscribeService(
                Subscribe)));  

Answer 1

您正在构造的对象需要在构造函数中提供运行时详细信息，并且可能（帖子中的假设）与其他对象（如其本身）共享一个公共接口 - 这不是很好，但也不是悲剧 - 它只是使事情变得复杂。

您还可以应用构建器/抽象工厂模式并配置依赖注入来注入所述构建器/工厂服务，以便客户端可以根据一些运行时数据解析实际需要的实现。

如果可能，您可以尝试在 DI 容器中从头开始完全注册此 (BaseOrderProcessing) 服务，并将其注入为完全配置的服务（如果您不必基于某些运行时输入数据来解析它，但例如您正在从 json 获取配置）启动此应用程序时创建文件。

您还可以重新设计您的服务，以便将其作为未初始化的注入，并通过某种方法向其提供 SubscribeDetails - 这将简化 DI 配置。