Autofac 在深层解析

Question

我很难将 autofac 集成到我的应用程序中..

我的应用程序与其他应用程序集成，当与另一个应用程序的连接由合适的 "Protocol" 对象维护时

// This class is inherited by a few other classes
public abstract class Protocol

我有一个层运行由它自己的线程处理连接请求。对于每种请求，都会创建不同类型的协议（不同的协议对象）

// For example lets say every protocol (Inhertiance of Protocol abstract object) 
// takes in ctor these 3 services + runtime configuration object:
public Protocol1(IFramingAgent, IFramingAlgorithm, IFramingParser, configObject configuration)

我的协议对象被键控注册为协议。还，每个服务都使用密钥注册，因为每个协议使用从同一接口继承的不同类型。当然，所有这些都被注册为 PerDependency（虽然我不太明白这个 lifeCycle 和 PerScope 之间的区别，非常感谢解释）

这是我最糟糕的 class:

public class ProtocolsLayer : Layer
{
    private IFrameworkDependencyResolver _resolver;
    private IConfigurationService _configService;

    public ProtocolsLayer(IFrameworkDependencyResolver resolver, IConfigurationService configurationService)
    {
        _resolver = resolver;
        _configService = configurationService;
    }

    void HandleConnection1()
    {
        // What I have at the moment (terrible):

        // Resolve the fitting services (All keyed - key is received by the type, Resolve and ResolveWithParameters used here are my wrappers)
        var agent = _resolver.Resolve<IFramingAgent>(typeof(Protocol1FramingAgent));

        var algo = _resolver.Resolve<IFramingAlgorithm>(typeof(Protocol1FramingAlgorith));

        var parser = _resolver.Resolve<IFramingParser>(typeof(Protocol1FramingParser));

        // A parameter I get and pass to each protocol at runtime
        var protocolConfig = _configService.GetConfig<Protocol1Configuration>();

        // Finally resolve the protocol with it's parameters:

        protocol = _resolver.ResolveWithParameters<IProtocol>(typeof(Protocol1), new List<object>{
            agent, resolver, parser, protocolConfig 
        });

        //...

        // Theres gotta be a better way!! 
    }

    void HandleConntection2()
    {
        // Same as in protocol1
    }

    void HandleConnection3()
    {
        // Same as in protocol1
    }
}

请记住，我不想引用 autofac，这意味着我不能使用我听说过的 IIndex<>。

谢谢！

Answer 1

您应该让依赖注入框架管理实例化。

您使用 ResolveWithParameter 方法，其中这些参数已由依赖项注入框架解析。这不是必需的，您可以让框架为您找到依赖项：

如果Protocol1需要命名参数，您可以在注册过程中指定。

builder.Register(c => c.Resolve<IConfigurationService>()
                       .GetConfig<Protocol1Configuration>())
       .As<Protocol1Configuration>(); 

builder.RegisterType<Protocol1>()
       .Named<IProtocol1>(nameof(Protocol1))
       .WithParameter((pi, c) => pi.ParameterType == typeof(IFramingAgent), 
                      (pi, c) => c.ResolveNamed<IFramingAgent>(nameof(Protocol1))
       .WithParameter((pi, c) => pi.ParameterType == typeof(IFramingAlgorithm), 
                      (pi, c) => c.ResolveNamed<IFramingAlgorithm>(nameof(Protocol1));
builder.RegisterType<FramingAgentProtocol1>()
       .Named<IFramingAgent>(nameof(Protocol1));
builder.RegisterType<FramingAlgorithmProtocol1>()
       .Named<IFramingAlgorithm>(nameof(Protocol1));

那么ProtocolsLayer只需要依赖IIndex<String, Func<IProtocol>>（或Func<Owned<Protocol1>>）

public class ProtocolsLayer 
{
    public ProtocolsLayer(IIndex<String, Func<IProtocol>> index)
    {
        this._index = index; 
    }

    private readonly IIndex<String, Func<IProtocol>> _index;

    public void HandleConnection1()
    {
        IProtocol protocol = this._index[nameof(Protocol1)](); 
    }
}

如果您不想为整个应用程序引入对 IIndex<,> 的依赖，您可以引入将在运行时定义的 IProtocolFactory 并仅为注册项目创建实现。

在您的运行时项目中：

public interface IProtocolFactory
{
    IProtocol Create(String protocolName)
}

在您的注册项目中：

public class ProtocolFactory : IProtocolFactory
{

    public ProtocolFactory(IIndex<String, IProtocol> index)
    {
        this._index = index; 
    }

    private readonly IIndex<String, IProtocol> _index; 

    public IProtocol Create(String protocolName)
    {
        return this._index[typeof(TProtocol).Name]; 
    }
}

那么你 ProtocolsLayer class 会是这样的：

public class ProtocolsLayer 
{
    public ProtocolsLayer(IProtocolFactory protocolFactory)
    {
        this._protocolFactory = protocolFactory; 
    }

    private readonly IProtocolFactory _protocolFactory;

    public void HandleConnection1()
    {
        IProtocol protocol = this._protocolFactory.Create("Protocol1"); 
    }
}

你也可以注册一个Func<String, IProtocol> 将命名为resolve IProtocol

ProtocolsLayer 看起来像这样：

public class ProtocolsLayer 
{
    public ProtocolsLayer(Func<String, IProtocol> protocolFactory)
    {
        this._protocolFactory = protocolFactory; 
    }

    private readonly Func<String, IProtocol> _protocolFactory;

    public void HandleConnection1()
    {
        IProtocol protocol = this._protocolFactory("Protocol1"); 
    }
}

和这样的注册：

builder.Register(c => (String namedProtocol) => c.ResolveNamed<IProtocol>(namedProtocol)
       .As<Func<String, IProtocol>>();

但我不会推荐这个解决方案，因为 Func<String, IProtocol> protocolFactory 依赖的意图不明确。拥有 IProtocolFactory 接口使依赖目标易于理解。

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