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带有Ninject的装饰图案

service-layer ninject dependency-injection c#

Mehrdad Kamelzadeh · 技术社区 · 11 年前

我正在申请 this 制作验证包装器的方法。我已经创建了以下接口,我正在使用Ninject作为我的DI容器

public interface ICommandHandler<TCommand>
    {
        void Handle(TCommand command);
    }

public interface IValidator<T>
{
    IEnumerable<ValidationResult> Validate(T command);
}

public class ValidationCommandHandlerDecorator<T>:ICommandHandler<T>
{
    private readonly ICommandHandler<T> _decoratee;
    private readonly IValidator<T> _validator;

    public ValidationCommandHandlerDecorator(ICommandHandler<T> decoratee,IValidator<T> validator )
    {
        _decoratee = decoratee;
        _validator = validator;
    }
    public void Handle(T command)
    {
        this._validator.Validate(command);
        this._decoratee.Handle(command);
    }
}

public class SaveNewOsiRequestController : ApiController
{
    private readonly ICommandHandler<OsiRequest> _osiRequestSaveHandler;

    public SaveNewOsiRequestController(ICommandHandler<OsiRequest> osiRequestSaveHandler)
    {
        _osiRequestSaveHandler = osiRequestSaveHandler;
    }
}

下面是我如何将具体类注入控制器的过程:

        kernel.Bind(typeof (IValidator<>)).To(typeof (OsiRequestValidator));

        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (SaveOsiRequestCommandHandler))
            .WhenInjectedInto(typeof (ValidationCommandHandlerDecorator<>));

        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ValidationCommandHandlerDecorator<>))
            .WhenInjectedInto(typeof(SaveNewOsiRequestController));

代码运行良好,没有任何问题。然而,问题是我如何使用Ninject为另一个控制器进行相同的注射?为了简单起见,我想注射另一种 Validator 和另一个 CommandHandler 到另一个 Controller 这样地:

        kernel.Bind(typeof (IValidator<>)).To(typeof (ANOTHER_Validator));

        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ANOTHER_CommandHandler))
            .WhenInjectedInto(typeof (ValidationCommandHandlerDecorator<>));

        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ValidationCommandHandlerDecorator<>))
            .WhenInjectedInto(typeof(ANOTHER_RequestController));

1 回复 | 直到 11 年前

Erik Funkenbusch 11 年前

这里的问题是,您在执行泛型绑定,但您在特定情况下使用它。只有当您希望通用绑定应用于该绑定的所有情况(或至少可以有条件地绑定到的所有情况)时,才希望使用通用绑定。

为此,您可以轻松地执行以下操作:

kernel.Bind<IValidator<OsiRequest>>().To<OsiRequestValidator>();

kernel.Bind<ICommandHandler<OsiRequest>()
        .To<SaveOsiRequestCommandHandler>()
        .WhenInjectedInto<ValidationCommandHandlerDecorator<OsiRequest>>();

kernel.Bind<ICommandHandler<OsiRequest>()
        .To<ValidationCommandHandlerDecorator<OsiRequest>()
        .WhenInjectedInto<SaveNewOsiRequestController>();

然后,每个附加值将是:

kernel.Bind<IValidator<DifferentRequest>>().To<DifferentValidator>();

kernel.Bind<ICommandHandler<DifferentRequest>()
        .To<DifferentRequestCommandHandler>()
        .WhenInjectedInto<ValidationCommandHandlerDecorator<DifferentRequest>>();

kernel.Bind<ICommandHandler<DifferentRequest>()
        .To<ValidationCommandHandlerDecorator<DifferentRequest>()
        .WhenInjectedInto<DifferentRequestController>();

您可以更改最后一个绑定,这样就不必为每个类型声明它:

kernel.Bind(typeof (ICommandHandler<>))
        .To(typeof (ValidationCommandHandlerDecorator<>))
        .WhenInjectedInto<ApiController>();