我正在尝试使用SimpleInjector作为IOC容器,到目前为止我对此非常满意.但是现在我遇到了一个我无法解决的问题.我搜索了SO和文档,但似乎还没有回答.我见过
the howto doc from SimpleInjector,但不包括开放的通用接口.
我有两个这样的通用接口：
public interface IEventPublisher<TEvent>
{
void Publish(TEvent Event);
}
public interface IEventSubscriber<TEvent>
{
void Subscribe(Action<TEvent> CallBack);
}
这两个开放的通用实现：
class EventMediator<T> : IEventPublisher<T>,IEventSubscriber<T>
{
List<Action<T>> Subscriptions = new List<Action<T>>();
public void Publish(T Event)
{
foreach (var Subscription in this.Subscriptions)
Subscription.Invoke(Event);
}
public void Subscribe(Action<T> CallBack)
{
this.Subscriptions.Add(CallBack);
}
}
在我的应用程序中,我正在设置SimpleInjector,如下所示：
this.Container = new SimpleInjector.Container(); this.Container.RegisterOpenGeneric(typeof(IEventPublisher<>),typeof(EventMediator<>),Lifestyle.Singleton); this.Container.RegisterOpenGeneric(typeof(IEventSubscriber<>),Lifestyle.Singleton); this.Container.Verify();
我想要存档的是：
在要求IEventPublisher或IEventSubscriber时,我想获得完全相同的实例.此外,此实例应为任何T的单例.
我用这些线测试了这个：
class DummyEvent {}
var p = this.Container.GetInstance<IEventPublisher<DummyEvent>>();
var s = this.Container.GetInstance<IEventSubscriber<DummyEvent>>();
var areSame = (object.ReferenceEquals(p,s));
不幸的是,p和s并没有引用相同的实例.有人碰巧知道这个问题的解决方案吗？
解决方法
对此有一些解决方案,这里是一个：为IEventPublisher创建单独的实现< T>和IEventSubscriber< T>并让他们委托给EventMediator< T>.例如,使用这些实现：
public class EventPublisher<TEvent> : IEventPublisher<TEvent>
{
private readonly EventMediator<TEvent> mediator;
public EventPublisher(EventMediator<TEvent> mediator) {
this.mediator = mediator;
}
public void Publish(TEvent Event) {
this.mediator.Publish(Event);
}
}
public class EventSubscriber<TEvent> : IEventSubscriber<TEvent>
{
private readonly EventMediator<TEvent> mediator;
public EventSubscriber(EventMediator<TEvent> mediator) {
this.mediator = mediator;
}
public void Subscribe(Action<TEvent> CallBack) {
this.mediator.Subscribe(Callback);
}
}
现在您进行如下注册：
container.RegisterSingleOpenGeneric(typeof(EventMediator<>),typeof(EventMediator<>)); container.RegisterSingleOpenGeneric(typeof(IEventPublisher<>),typeof(EventPublisher<>)); container.RegisterSingleOpenGeneric(typeof(IEventSubscriber<>),typeof(EventSubscriber<>));
现在两个EventPublisher< DummyEvent>和EventSubscriber< DummyEvent>将指向相同的EventMediator< DummyEvent>实例.
在没有额外类型的情况下实现此目的的另一种方法是使用ResolveUnregisteredType事件(这是RegisterOpenGeneric扩展方法本身在封面下使用的事件).您的配置如下所示：
container.RegisterSingleOpenGeneric(typeof(EventMediator<>),typeof(EventMediator<>));
container.ResolveUnregisteredType += (s,e) =>
{
if (e.UnregisteredServiceType.IsGenericType)
{
var def = e.UnregisteredServiceType.GetGenericTypeDefinition();
if (def == typeof(IEventPublisher<>) || def == typeof(IEventSubscriber<>))
{
var mediatorType = typeof(EventMediator<>)
.MakeGenericType(e.UnregisteredServiceType.GetGenericArguments()[0]);
var producer = container.GetRegistration(mediatorType,true);
e.Register(producer.Registration);
}
}
};
您甚至可以将此代码提取到更通用的扩展方法中.这样您的注册将如下所示：
container.RegisterSingleOpenGeneric(typeof(EventMediator<>),typeof(EventMediator<>)); container.ForwardOpenGenericTo(typeof(IEventPublisher<>),typeof(EventMediator<>)); container.ForwardOpenGenericTo(typeof(IEventSubscriber<>),typeof(EventMediator<>));
扩展方法如下所示：
public static void ForwardOpenGenericTo(this Container container,Type openGenericServiceType,Type openGenericServiceTypeToForwardTo)
{
container.ResolveUnregisteredType += (s,e) =>
{
var type = e.UnregisteredServiceType;
if (type.IsGenericType)
{
if (type.GetGenericTypeDefinition() == openGenericServiceType)
{
var forwardToType = openGenericServiceTypeToForwardTo.MakeGenericType(
type.GetGenericArguments());
var producer = container.GetRegistration(forwardToType,true);
e.Register(producer.Registration);
}
}
};
}
