统一的自定义对象工厂扩展

为了完整性,我应该添加另一个在Unity2下工作的答案,因为我的另一个答案不再有效。因为您需要制定一个自定义的构建器策略,所以它稍微涉及一些。感谢Unity项目的CTavares,他在 this thread 在实施过程中:

public class FactoryUnityExtension : UnityContainerExtension
{
    private ICustomFactory factory;
    private CustomFactoryBuildStrategy strategy;

    public FactoryUnityExtension(ICustomFactory factory)
    {
        this.factory = factory;
    }

    protected override void Initialize()
    {
        this.strategy = new CustomFactoryBuildStrategy(factory, Context);
        Context.Strategies.Add(strategy, UnityBuildStage.PreCreation);
        Context.Policies.Set<ParentMarkerPolicy>(new ParentMarkerPolicy(Context.Lifetime), new NamedTypeBuildKey<ParentMarkerPolicy>());
    }
}

public class ParentMarkerPolicy : IBuilderPolicy
{
    private ILifetimeContainer lifetime;

    public ParentMarkerPolicy(ILifetimeContainer lifetime)
    {
        this.lifetime = lifetime;
    }

    public void AddToLifetime(object o)
    {
        lifetime.Add(o);
    }
}

public interface ICustomFactory
{
    object Create(Type t);
    bool CanCreate(Type t);
}

public class CustomFactoryBuildStrategy : BuilderStrategy
{
    private ExtensionContext baseContext;
    private ICustomFactory factory;


    public CustomFactoryBuildStrategy(ICustomFactory factory, ExtensionContext baseContext)
    {
        this.factory = factory;
        this.baseContext = baseContext;
    }

    public override void PreBuildUp(IBuilderContext context)
    {
        var key = (NamedTypeBuildKey)context.OriginalBuildKey;

        if (factory.CanCreate(key.Type) && context.Existing == null)
        {
            context.Existing = factory.Create(key.Type);
            var ltm = new ContainerControlledLifetimeManager();
            ltm.SetValue(context.Existing);

            // Find the container to add this to
            IPolicyList parentPolicies;
            var parentMarker = context.Policies.Get<ParentMarkerPolicy>(new NamedTypeBuildKey<ParentMarkerPolicy>(), out parentPolicies);

            // TODO: add error check - if policy is missing, extension is misconfigured

            // Add lifetime manager to container
            parentPolicies.Set<ILifetimePolicy>(ltm, new NamedTypeBuildKey(key.Type));
            // And add to LifetimeContainer so it gets disposed
            parentMarker.AddToLifetime(ltm);

            // Short circuit the rest of the chain, object's already created
            context.BuildComplete = true;
        }
    }
}

更新 这个答案是为了统一1.2。关于与Unity2一起工作的解决方案,请参阅我的另一个答案。

好的,我自己已经实现了扩展。在构建器中,我缓存对象,因为我希望它是一个单独的w.r.t我的容器。原因 baseContext 我希望将它缓存在顶级容器中,而不是从中请求它的任何子容器中。

 public class FactoryMethodUnityExtension<T> : UnityContainerExtension
 {
     private Func<Type,T> factory; 

     public FactoryMethodUnityExtension(Func<Type,T> factory)
     {
         this.factory = factory;
     }

     protected override void Initialize()
     {
         var strategy = new CustomFactoryBuildStrategy<T>(factory, this.Context);
         Context.Strategies.Add(strategy, UnityBuildStage.PreCreation);             
     }
 } 

 public class CustomFactoryBuildStrategy<T> : BuilderStrategy
 {
     private Func<Type,T> factory;
     private ExtensionContext baseContext;

     public CustomFactoryBuildStrategy(Func<Type,T> factory, ExtensionContext baseContext)
     {
        this.factory = factory;
        this.baseContext = baseContext;
     }

     public override void PreBuildUp(IBuilderContext context)
     {
         var key = (NamedTypeBuildKey)context.OriginalBuildKey;

         if (key.Type.IsInterface && typeof(T).IsAssignableFrom(key.Type))
         {
             object existing = baseContext.Locator.Get(key.Type);
             if (existing == null)
             {
                 // create it
                 context.Existing = factory(key.Type);
                 // cache it
                 baseContext.Locator.Add(key.Type, context.Existing);
             }
             else
             {
                 context.Existing = existing;
             }
         }
     }
 }

添加扩展非常简单:

MyFactory factory = new MyFactory();
container = new UnityContainer();
container.AddExtension(new FactoryMethodUnityExtension<IBase>(factory.Create));

Unity(V2)允许您指定工厂。它允许两个不同的函数,包括使用类型构建/名称等。简单示例:

UnityContainer cont = new UnityContainer();

有一个简单的创建测试方法-但这可以扩展到任何你想要的工厂。
这将绕过正常的创建过程,即(为了简洁起见)调用 最长的构造函数 包括属性设置在内的所有后续行为仍将执行。

cont.RegisterType<TestClass>(new InjectionFactory(c => CreateTest()));

var svc = cont.Resolve<TestClass>();

Unity容器已经充当了一个知道如何构造(和执行)任意类型的工厂,因此接受T类型的工厂看起来是多余的。你能详细解释一下为什么这是不可能的吗?

如果这真的是不可能的(更可能是太多的工作),那么也许你可以用容器来注册你的工厂?