Autofac-注册多个装饰器 [英] Autofac - Register multiple decorators

问题描述

给出以下内容:

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

public class MoveCustomerCommand
{

}

public class MoveCustomerCommandHandler : ICommandHandler<MoveCustomerCommand>
{
    public void Handle(MoveCustomerCommand command)
    {
        Console.WriteLine("MoveCustomerCommandHandler");
    }
}

public class TransactionCommandHandlerDecorator<TCommand> : ICommandHandler<TCommand>
{
    private readonly ICommandHandler<TCommand> _decorated;

    public TransactionCommandHandlerDecorator(ICommandHandler<TCommand> decorated)
    {
        _decorated = decorated;
    }

    public void Handle(TCommand command)
    {
        Console.WriteLine("TransactionCommandHandlerDecorator - before");
        _decorated.Handle(command);
        Console.WriteLine("TransactionCommandHandlerDecorator - after");
    }
}

public class DeadlockRetryCommandHandlerDecorator<TCommand> : ICommandHandler<TCommand>
{
    private readonly ICommandHandler<TCommand> _decorated;

    public DeadlockRetryCommandHandlerDecorator(ICommandHandler<TCommand> decorated)
    {
        _decorated = decorated;
    }

    public void Handle(TCommand command)
    {
        Console.WriteLine("DeadlockRetryCommandHandlerDecorator - before");
        _decorated.Handle(command);
        Console.WriteLine("DeadlockRetryCommandHandlerDecorator - after");
    }
}

我可以使用以下代码用TransactionCommandHandlerDecorator装饰MoveCustomerCommandHandler:

I can decorate the MoveCustomerCommandHandler with a TransactionCommandHandlerDecorator using the following code:

var builder = new ContainerBuilder();

builder.RegisterAssemblyTypes(typeof(MoveCustomerCommandHandler).Assembly)
    .As(type => type.GetInterfaces()
    .Where(interfaceType => interfaceType.IsClosedTypeOf(typeof(ICommandHandler<>)))
    .Select(interfaceType => new KeyedService("commandHandler", interfaceType)));

builder.RegisterGenericDecorator(
        typeof(TransactionCommandHandlerDecorator<>),
        typeof(ICommandHandler<>),
        fromKey: "commandHandler");

var container = builder.Build();

var commandHandler = container.Resolve<ICommandHandler<MoveCustomerCommand>>();
commandHandler.Handle(new MoveCustomerCommand());

将输出:

TransactionCommandHandlerDecorator - before  
MoveCustomerCommandHandler 
TransactionCommandHandlerDecorator - after 

如何用DeadlockRetryCommandHandlerDecorator装饰TransactionCommandHandlerDecorator，以生成以下输出

How can I also decorate the TransactionCommandHandlerDecorator with the DeadlockRetryCommandHandlerDecorator, to generate the following output

DeadlockRetryCommandHandlerDecorator- before
TransactionCommandHandlerDecorator - before  
MoveCustomerCommandHandler 
TransactionCommandHandlerDecorator - after 
DeadlockRetryCommandHandlerDecorator- after

推荐答案

您只需要将"TransactionCommandHandlerDecoratored" ICommandHandler注册为Keyed服务，并在注册第二个DeadlockRetryCommandHandlerDecorator时使用该新密钥:

You just need to register your "TransactionCommandHandlerDecoratored" ICommandHandler as a Keyed service and use that new key when registering your second DeadlockRetryCommandHandlerDecorator:

builder.RegisterGenericDecorator(
        typeof(TransactionCommandHandlerDecorator<>),
        typeof(ICommandHandler<>),
        fromKey: "commandHandler")
        .Keyed("decorated", typeof(ICommandHandler<>));

builder.RegisterGenericDecorator(
        typeof(DeadlockRetryCommandHandlerDecorator<>),
        typeof(ICommandHandler<>),
        fromKey: "decorated");

您将获得以下输出:

DeadlockRetryCommandHandlerDecorator - before
TransactionCommandHandlerDecorator - before
MoveCustomerCommandHandler
TransactionCommandHandlerDecorator - after
DeadlockRetryCommandHandlerDecorator - after

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