如何在使用 RegisterAssemblyType 时向 Autofac 注册装饰器
本文关键字:注册 Autofac 时向 RegisterAssemblyType | 更新日期: 2023-09-27 18:31:14
这是我的代码
public interface ICommandHandler<T>
{
void Handle(T command);
}
public class CreateUserCommandHandler : ICommandHandler<CreateUserCommand>
{
public void Handle(CreateUserCommand command)
{
// do something with the command
}
}
public class LoggingCommandDecorator<TCommand> : ICommandHandler<TCommand>
{
private readonly ICommandHandler<TCommand> _commandHandler;
public LoggingCommandDecorator(ICommandHandler<TCommand> commandHandler)
{
_commandHandler = commandHandler;
}
public void Handle(TCommand command)
{
Debug.WriteLine("Logging...");
_commandHandler.Handle(command);
}
}
这是我的注册:
private void SetupAutofac()
{
var builder = new ContainerBuilder();
// Register your MVC controllers.
builder.RegisterControllers(typeof(WebApiApplication).Assembly);
// OPTIONAL: Register model binders that require DI.
builder.RegisterModelBinders(Assembly.GetExecutingAssembly());
builder.RegisterModelBinderProvider();
var assemblies = AppDomain.CurrentDomain.GetAssemblies();
builder.RegisterAssemblyTypes(assemblies)
.As(o => o.GetInterfaces()
.Where(i => i.IsClosedTypeOf(typeof(ICommandHandler<>)))
.Select(i => new KeyedService("Handler", i)));
builder.RegisterGenericDecorator(typeof(LoggingCommandDecorator<>),
typeof(ICommandHandler<>),
"Handler", "DecoratedHandler");
var container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}
当我运行此代码时,出现以下异常:
没有找到任何构造函数 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' on type "AspectDemo.Controllers.HomeController"可以使用 可用服务和参数:无法解析参数 'AspectDemo.Business.ICommandHandler
1[AspectDemo.Business.Users.CreateUserCommand] createUserHandler' of constructor 'Void .ctor(AspectDemo.Business.ICommandHandler
1[AspectDemo.Business.Users.CreateUserCommand])'.
当我使用以下作为我的注册时,我没有得到例外,但我也没有任何装饰器。
builder.RegisterAssemblyTypes(assemblies)
.AsClosedTypesOf(typeof(ICommandHandler<>))
.AsImplementedInterfaces();
我需要做什么才能使用装饰器?
注意:现在我只使用一个装饰器,但最终我认为我有大约 4-5 个装饰器。
使用 RegisterGenericDecorator
方法的 toKey
参数时,它会导致命名注册,因此必须解析命名ICommandHandler
builder.RegisterGenericDecorator(
typeof(LoggingCommandDecorator<>),
typeof(ICommandHandler<>),
fromKey : "Handler",
toKey : "DecoratedHandler");
然后你可以这样解决它:
container.ResolveKeyed<ICommandHandler<CreateUserCommand>>("DecoratedHandler");
toKey
参数是可选的:
builder.RegisterGenericDecorator(
typeof(LoggingCommandDecorator<>),
typeof(ICommandHandler<>),
fromKey : "Handler");
然后你可以这样解决它:
container.Resolve<ICommandHandler<CreateUserCommand>>();
当您拥有中间装饰器时,toKey
很有用:
builder.RegisterGenericDecorator(
typeof(LoggingCommandDecorator<>),
typeof(ICommandHandler<>),
fromKey : "Original",
toKey : "Logging");
builder.RegisterGenericDecorator(
typeof(AuthorizationCommandDecorator<>),
typeof(ICommandHandler<>),
fromKey : "Logging");
在这种情况下,ICommandHandler<CreateUserCommand>
将由LoggingCommandDecorator<>
和AuthorizationCommandDecorator<>
装饰