我正在使用Unity IoC容器,我需要拦截对某个基本界面的Resolve的任何调用,并运行我自己的自定义代码来构造这些类型.
换句话说,在下面的示例代码中,当我调用container.Resolve< IFooN>()时,如果没有具体实现类型的实例,它调用MyFactoryFunction构造一个,否则我希望它返回缓存副本.
标准的Unity容器不能构造这些对象(更新：因为它们是.NET远程处理对象,所以具体的类不存在于本地计算机上的任何程序集中),我不想在前面创建它们用RegisterInstance存储它们.
interface IFoo : IBase { ... }
interface IFoo2 : IBase { ... }
...
container.Resolve<IFoo2>();
...
IBase MyFactoryFunction(Type t)
{
...
}
我假设我可以创建一个Unity扩展来做到这一点,但我想知道是否已经有一个可以借用的解决方案.
解决方法
为了完整,我应该添加另一个在Unity 2下工作的答案,因为我的其他答案不再有效.由于您需要制定自定义构建器策略,因此它的参与程度有所增加.感谢Unity项目的ctavares,他为
this thread提供了大量的帮助：
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;
}
}
}