通过 IAsyncInterceptor 使用 Autofac 接口拦截

Question

我确实使用了这个文档： https://autofaccn.readthedocs.io/en/latest/advanced/interceptors.html

实现接口拦截器。为了处理我的异步调用，我使用了此处描述的 IAsyncInterceptor 接口：

https://github.com/JSkimming/Castle.Core.AsyncInterceptor

我想出的注册码是这样的：

 builder.Register(c => new CallResultLoggerInterceptor())
    .Named<IAsyncInterceptor>("log-calls");

  builder.RegisterType<AppointmentService>()
    .As<IAppointmentService>()
    .EnableInterfaceInterceptors()
    .InstancePerDependency();

AppointmentService 有一个 InterceptAttribute。

 [Intercept("log-calls")]
 public class AppointmentService : IAppointmentService
 ...

当我调用容器的 Build() 方法时，它会抛出一个带有以下消息的 ComponentNotRegisteredException：

请求的服务“log-calls (Castle.DynamicProxy.IInterceptor)”尚未注册。为避免此异常，请注册组件以提供服务，使用 IsRegistered() 检查服务注册，或使用 ResolveOptional() 方法解决可选依赖项。

这是正确的，因为我没有实现 IInterceptor 而是 IAsyncInterceptor。我想问题是使用 ProxyGenerator 的“错误”扩展方法在 autofac 中实现 EnableInterfaceInterceptors 的具体实现 - 但我该如何解决这个问题？

干杯， 曼努埃尔

Answer 1

您需要注册一个名为 IInterceptor 的 Autofac 拦截器才能工作。您正在注册IAsyncInterceptor。那是行不通的。

注意 Autofac 不支持您正在使用的这种扩展的异步拦截器扩展。如果你想让它工作，它需要编写一个具有某种性质的自定义适配器来让它响应IInterceptor。

Answer 2

您可以在 Castle.Core.AsyncInterceptor 的问题中看到我的回答： https://github.com/JSkimming/Castle.Core.AsyncInterceptor/issues/42#issuecomment-592074447

1. 创建适配器

public class AsyncInterceptorAdaper<TAsyncInterceptor> : AsyncDeterminationInterceptor
  where TAsyncInterceptor : IAsyncInterceptor
{
    public AsyncInterceptorAdaper(TAsyncInterceptor asyncInterceptor)
        : base(asyncInterceptor)
    { }
}

1. 创建您的异步拦截器

public class CallLoggerAsyncInterceptor : AsyncInterceptorBase  
{
  ....
}

1. 将拦截器与接口相关联

[Intercept(typeof(AsyncInterceptorAdaper<CallLoggerAsyncInterceptor>))]
public interface ISomeType

4. 注册到 IoC 容器

//register adapter
builder.RegisterGeneric(typeof(AsyncInterceptorAdaper<>));
//register async interceptor
builder.Register(c => new CallLoggerAsyncInterceptor(Console.Out));   

我在https://github.com/wswind/aop-learn/blob/master/AutofacAsyncInterceptor做了一个代码示例

Answer 3

我创建了自己的扩展方法来注册应用程序服务。 这种扩展方法只是为城堡核心ProxyGenerator准备输入参数。

using System;
using System.Collections.Generic;
using System.Linq;
using Castle.DynamicProxy;
using Autofac;

namespace pixi.Extensions
{
    public static class AutofacExtensions
    {
        private static readonly ProxyGenerator _proxyGenerator = new ProxyGenerator();

        /// <summary>
        /// Use this extension method to register default interceptors <code>UnitOfWorkInterceptor</code>
        /// and <code>LoggingInterceptor</code> on your application service implementations. If you need custom
        /// interceptors that are not part of infrastructure but are part of specific business module then pass
        /// in those interceptors in params explicitly.
        /// </summary>
        /// <param name="builder"></param>
        /// <param name="interceptors"></param>
        /// <typeparam name="TImplementation"></typeparam>
        /// <typeparam name="TService"></typeparam>
        /// <exception cref="ArgumentException"></exception>
        public static void RegisterApplicationService<TImplementation, TService>(this ContainerBuilder builder, params Type[] interceptors)
            where TImplementation : class
        {
            ValidateInput<TService>(interceptors);

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

            builder.Register(c =>
            {
                var service = c.Resolve<TImplementation>();
                var resolvedInterceptors = ResolveInterceptors<TImplementation, TService>(interceptors, c);

                return (TService) _proxyGenerator.CreateInterfaceProxyWithTarget(
                        typeof(TService),
                        service,
                        ProxyGenerationOptions.Default,
                        resolvedInterceptors
                    );
            }).As<TService>();
        }

        private static void ValidateInput<TService>(Type[] interceptors)
        {
            if (!typeof(TService).IsInterface)
                throw new ArgumentException("Type must be interface");
            if (interceptors.Any(i => i != typeof(IAsyncInterceptor)))
                throw new ArgumentException("Only IAsyncInterceptor types are expected");
        }

        private static IAsyncInterceptor[] ResolveInterceptors<TImplementation, TService>(Type[] interceptors,
            IComponentContext c) where TImplementation : class
        {
            var resolvedInterceptors = new List<IAsyncInterceptor>
            {
                c.Resolve<LoggingInterceptor>(),
                c.Resolve<UnitOfWorkInterceptor>()
            }.Concat(interceptors
                .Where(i => i != typeof(UnitOfWorkInterceptor)
                            && i != typeof(LoggingInterceptor))
                .Select(i => (IAsyncInterceptor) c.Resolve(i))).ToArray();
            return resolvedInterceptors;
        }
    }
}

我将城堡核心用于工作单元和日志记录，因此名称为 UnitOfWorkInterceptor 和 LogginInterceptor。将这两个更改为您想要的默认值。默认拦截器必须以这种方式注册：

public class SomeModule: Module
    {
        protected override void Load(ContainerBuilder builder)
        {
            builder.RegisterType<UnitOfWorkInterceptor>().AsSelf();
            builder.RegisterType<LoggingInterceptor>().AsSelf();
            builder.RegisterApplicationService<SampleService, ISampleService>();
            builder.RegisterType<SampleRepository>().As<ISampleRepository>();
        }
    }

在上面的代码 sn-p 中，我还演示了使用提供的扩展方法。这样做我会得到红色的标签接口并在接口上放置额外的属性。这样我就可以让我的 ApplicationService 接口不受框架/第三方库的依赖。

我希望这会有所帮助。