Ninject C# 中的工厂方法

Question

我有一个名为 IBreakfastProvider 的接口，它有多个实现。目前，我的代码根据 id 决定使用哪一个。它使用工厂方法，如下所示：

public IBreakfastProvider GetBreakfastProvider(int id)
{
    switch (id)
    {
        case 1:
            return new CornFlakeProvider(new SomeDependency());
        case 2:
            return new MuesliProvider(new SomeOtherDependency());
        case 3:
            return new ToastProvider();
        default:
            throw new ApplicationException("Unknown provider id."); 
    }
}

IBreakfast 提供程序的每个实现都可以有自己的依赖项。如何替换此方法以使用 Ninject 根据此整数 ID 计算出要使用的实现？

Answer 1

您可以为每种类型注册一个名称。然后，当您需要解析时，只需将 id 传递给 Ninject:

// Use better naming though :)
kernel.Bind<IBreakfastProvider>().To<CornFlakeProvider>().Named("1");

然后当你解决：

var breakfastProvider = resolutionRoot.Get<IFoo>(id);

Answer 2

使用构造函数注入：

public class BreakfastProviderFactory
{
    private readonly CornFlakeProvider provider1;
    private readonly MuesliProvider provider2;
    private readonly ToastProvider provider3;

    public BreakfastProviderFactory(CornFlakeProvider provider1,
        MuesliProvider provider2, ToastProvider provider3) {
    {
        this.provider1 = provider1;
        this.provider2 = provider2;
        this.provider3 = provider3;
    }

    public IBreakfastProvider GetBreakfastProvider(int id)
    {
        switch (id)
        {
            case 1: return this.provider1;
            case 2: return this.provider2;
            case 3: return this.provider3;
            default: throw new ApplicationException("Unknown provider id."); 
        }
    }
}

Ninject C# 中的工厂方法

Factory methods in Ninject C#

c#

ninject