dependency-injection - 如何使用流畅的 API 在 Kephas 中注册服务？

Question

我想保留 Kephas 提供的 DI 抽象层，但在我的特殊情况下，我需要注册一个从第三方库导入的服务。鉴于此，我无法使用[AppServiceContract]服务注册所需的属性来注释服务。有没有办法做到这一点？

Answer 1

就在这里。以下是要遵循的步骤：

• 定义一个实现IConventionsRegistrar.
• 使用约定构建器来注册所需的服务。

示例代码：

public class MyConventionsRegistrar : IConventionsRegistrar
{
    /// <summary>
    /// Registers the conventions.
    /// </summary>
    /// <param name="builder">The registration builder.</param>
    /// <param name="candidateTypes">The candidate types which can take part in the composition.</param>
    /// <param name="registrationContext">Context for the registration.</param>
    public void RegisterConventions(
        IConventionsBuilder builder,
        IEnumerable<TypeInfo> candidateTypes,
        ICompositionRegistrationContext registrationContext)
    {
        //... here you can use the conventions builder to register your services using the fluent API. The candidate types are provided if you need the  identified application types. A couple of examples are provided below:

        // shared/singleton service exported as IMyService with MyService implementation.
        builder.ForType(typeof(MyServiceImpl))
               .Export(b => b.AsContractType(typeof(IMyService)))
               .Shared();

        // instance-based multiple services exported as IMultiImplService
        builder.ForTypesDerivedFrom(typeof(IMultiImplService))
               .Export(b => b.AsContractType(typeof(IMultiImplService)));
    }

还有第二种注册服务的方法，但是通过服务描述符而不是流畅的 API。对于这种情况，请执行以下步骤：

• 定义一个实现IAppServiceInfoProvider.
• 返回所需服务的描述符。

与上述注册相同的示例代码：

public class MyAppServiceInfoProvider : IAppServiceInfoProvider
{
    /// <summary>
    /// Gets an enumeration of application service information objects.
    /// </summary>
    /// <param name="candidateTypes">The candidate types which can take part in the composition.</param>
    /// <param name="registrationContext">Context for the registration.</param>
    /// <returns>
    /// An enumeration of application service information objects and their associated contract type.
    /// </returns>
    public IEnumerable<(TypeInfo contractType, IAppServiceInfo appServiceInfo)> GetAppServiceInfos(IEnumerable<TypeInfo> candidateTypes, ICompositionRegistrationContext registrationContext)
    {
        yield return (typeof(IMyService).GetTypeInfo(), 
                      new AppServiceInfo(typeof(IMyService), 
                                         typeof(MyServiceImpl),
                                         AppServiceLifetime.Shared));
        yield return (typeof(IMultiImplService).GetTypeInfo(), 
                      new AppServiceInfo(typeof(IMultiImplService), 
                                         AppServiceLifetime.Instance, 
                                         allowMultiple: true));
    }

这两种情况都是自动发现的，并在适当的时候调用注册方法。但是，在第二种情况下，优点是注册可用作服务元数据以供以后查询。