Unity Understanding Lifetime Managers

Unity默认提供了ContainerControlledLifetimeManager、TransientLifetimeManager、HierarchicalLifetimeManager、PerResolveLifetimeManager、PerThreadLifetimeManager和ExternallyControlledLifetimeManager。

ContainerControlledLifetimeManager 就是单例模式，在整个AppDomain中类型实例只有一个。

IUnityContainer unityContainer = new UnityContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new ContainerControlledLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = unityContainer.Resolve<TextWriter>();
TextWriter textWriter2 = unityContainer.Resolve<TextWriter>();

Console.WriteLine(Object.ReferenceEquals(textWriter, textWriter2));

TransientLifetimeManager 每次都会创建一个类型的新实例。

IUnityContainer unityContainer = new UnityContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new TransientLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = unityContainer.Resolve<TextWriter>();
TextWriter textWriter2 = unityContainer.Resolve<TextWriter>();

Console.WriteLine(Object.ReferenceEquals(textWriter, textWriter2));

HierarchicalLifetimeManager 单例模式，和ContainerControlledLifetimeManager不同的是子Container和祖先Container不共享类型实例。

IUnityContainer unityContainer = new UnityContainer();
IUnityContainer childUnityContainer = unityContainer.CreateChildContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new HierarchicalLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = unityContainer.Resolve<TextWriter>();
TextWriter textWriter2 = childUnityContainer.Resolve<TextWriter>();

PerResolveLifetimeManager 和TransientLifetimeManager相同，每次调用Resolve函数都会返回新的类型实例。

IUnityContainer unityContainer = new UnityContainer();
IUnityContainer childUnityContainer = unityContainer.CreateChildContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new PerResolveLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = unityContainer.Resolve<TextWriter>();
TextWriter textWriter2 = unityContainer.Resolve<TextWriter>();

Console.WriteLine(Object.ReferenceEquals(textWriter, textWriter2));

PerThreadLifetimeManager 和ThreadStaticAttribute一样，同一个线程共享一个类型实例。

IUnityContainer unityContainer = new UnityContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new PerThreadLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = null;
TextWriter textWriter2 = null;

Semaphore semphore = new Semaphore(0, 2);

new Thread(() =>
{
　　textWriter = unityContainer.Resolve<TextWriter>();
　　semphore.Release();
}).Start();

new Thread(() =>
{
　　textWriter2 = unityContainer.Resolve<TextWriter>();
　　semphore.Release();
}).Start();

semphore.WaitOne();

Console.WriteLine(Object.ReferenceEquals(textWriter, textWriter2));

ExternallyControlledLifetimeManager 类型共享同一个实例，内部对类型实例weak reference。类型实例的生命周期管理完全交给外部。

IUnityContainer unityContainer = new UnityContainer();

unityContainer.RegisterType<TextWriter, StringWriter>(new ExternallyControlledLifetimeManager(), new InjectionConstructor());

TextWriter textWriter = unityContainer.Resolve<TextWriter>();
TextWriter textWriter2 = unityContainer.Resolve<TextWriter>();

Console.WriteLine(Object.ReferenceEquals(textWriter, textWriter2));