Question

在BasePage.cs类中，我具有以下IIndex属性，该属性应具有可以使用键访问的INotificationService的两个“或多个”实现。

public class BasePage : Page
{
    public IIndex<string, INotificationService<INotification>> NotificationServices { get; set; }

    public INotificationService<INotification> EmailService
    {
        get
        {
            return NotificationServices["emailService"];
        }
    }
    public INotificationService<INotification> FaxService
    {
        get
        {
            return NotificationServices["faxService"];
        }
    }
}

具体课程：

public class FaxNotificationService : INotificationService<FaxNotification>
{
    private IClient _smtpClient;
    public FaxNotificationService(IClient smtpClient)
    {
        _smtpClient = smtpClient;
    }
    public void Send(FaxNotification notification)
    {
        _smtpClient.Send(notification);
    }
}

public class EmailNotificationService : INotificationService<EmailNotification>
{
    private IClient _smtpClient;
    public EmailNotificationService(IClient smtpClient)
    {
        _smtpClient = smtpClient;
    }
    public void Send(EmailNotification notification)
    {
        _smtpClient.Send(notification);
    }
}

在Global.asax.cs

中

void Application_Start(object sender, EventArgs e)
    {
        var emailSmtp = new SmtpWrapper(new SmtpClient
        {
            ...
        });


        var faxSmtp = new SmtpWrapper(new SmtpClient
        {
           ...
        });

        var builder = new ContainerBuilder();

// before having the generic interface the following commented code worked perfectly fine

        //builder.RegisterType<EmailNotificationService>()
        //        .Named<INotificationService>("emailService")
        //        .WithParameter("smtpClient", emailSmtp);

        //builder.RegisterType<FaxNotificationService>()
        //       .Named<INotificationService>("faxService")
        //       .WithParameter("smtpClient", faxSmtp);

        builder.RegisterType<EmailNotificationService>()
            .Named<INotificationService<INotification>>("emailService")
            .WithParameter("smtpClient", emailSmtp);


        builder.RegisterType<BasePage>().AsSelf();

        var build = builder.Build();
        _containerProvider = new ContainerProvider(build);

        using (var scope = build.BeginLifetimeScope())
        {
            var service = scope.Resolve<BasePage>();
        }
    }

在Global.asax.cs中，我尝试以某种方式注册EmailNotificationService，但出现异常：

类型'NotificationServices.EmailNotificationService'不能分配给服务'emailService（Shared.NotificationServices.Abstractions.INotificationService`1 [[Shared.NotificationServices.Abstractions.INotification ...]

现在我知道为什么它不起作用了。因为在C＃中甚至无法执行以下操作：

INotificationService<INotification> service = new EmailNotificationService(new SmtpWrapper(new SmtpClient()));

后面的代码行将导致编译时错误：

无法将类型'NotificationServices.EmailNotificationService'隐式转换为'Shared.NotificationServices.Abstractions.INotificationService'。存在显式转换（您是否缺少演员表？）

所以任何有想法的人：）

Answer 1

它们可以实现相同的接口，但不一定必须被视为相同。类型是重要的区分因素。 Solving this is an FAQ in the docs.

如何解析System.Web.UI.Page中相同类型的多个依赖关系，其中这些依赖关系实现了通用接口

1 个答案: