通过fsharp 使用Enterprise Library Unity 3 - 三种拦截模式的探索
来源：程序员人生 发布时间：2014-11-04 08:43:47 阅读次数：3498次
这篇就3种拦截模式进行1下探索。
特性总结
| |
类型 |
特点 |
其他 |
| InterfaceInterceptor |
Innstance |
仅单接口 |
类内部函数相互援用也能没法引发拦截行动 |
| TransparentProxyInterceptor |
Instance |
多接口(接口之间可以切换) MarshalByRef 运行缓慢 接口类型（virtual, non-virtual, or interface） |
类内部函数相互援用也能没法引发拦截行动 |
| VirtualMethodInterceptor |
Type |
多接口 不能用在已有对象上，接口函数必须为virtual |
类内部函数相互援用也能引发拦截行动 |
回想1下类的声明，两个接口，1个实现。fsharp实现接口函数的方法与csharp其实不完全1致，会造成1些实现上的困扰，这在后面会提到。
type ITenantStore =
abstract member Msg : unit->unit
type TenantStore() as x=
//do printfn "new TenantStore %A" (x.GetHashCode())
interface ITenantStore with
member this.Msg() = printfn "Hello, it's TenantStore"
interface IDisposable with
member this.Dispose() = printfn "TenantStore hase been cleaned"
下面进行1些测试。
let showregistrations (container:UnityContainer) =
container.Registrations |> Seq.iter (fun i -> printfn "Regist Type:%A" i.RegisteredType)
using(new UnityContainer())(fun ctner->
ctner.AddNewExtension<Interception>() |> ignore
ctner.RegisterType<ITenantStore, TenantStore>(new Interceptor<TransparentProxyInterceptor>(),//后续对此注入策略进行切换
new InterceptionBehavior<LogingInterceptionBehavior>()) |> ignore
showregistrations ctner
let t = ctner.Resolve<ITenantStore>()
t.Msg())
showregistrations 显示已注册的类型，用来展现注册内部的信息。另外，在交互式代码中使用using相较于use更加的适合，FSI声明的对象的生命周期是全局的，在做实验的时候没法控制container，反复清环境不太方便。
TransparentProxyInterceptor的结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
From the logging interceptor: "Invoke method System.Type GetType():System.Object at 16:20:45"
From the logging interceptor: "Method System.Type GetType():System.Object returned FSI_0002+TenantStore at 16:20:45"
From the logging interceptor: "Invoke method Void Msg():FSI_0002+ITenantStore at 16:20:45"
Hello, it's TenantStore
From the logging interceptor: "Method Void Msg():FSI_0002+ITenantStore returned at 16:20:45"
val it : unit = ()
InterfaceInterceptor的结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
From the logging interceptor: "Invoke method Void Msg():FSI_0002+ITenantStore at 16:22:54"
Hello, it's TenantStore
From the logging interceptor: "Method Void Msg():FSI_0002+ITenantStore returned at 16:22:54"
val it : unit = ()
虽然对象有两个接口，IDiposable接口和ITenantStore接口，拦截依然成功了，所以支持多对象指的是接口之间的切换，并不是不支持实现多对象的类。
VirtualMethodInterceptor的结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
Hello, it's TenantStore
val it : unit = ()
拦截失败。 研究后发觉是由于Fsharp中其实不直接支持Virtual方法，Fsharp实现接口成员，默许为显示（explicit）实现，想要申明Virtual方法需要1些技能。
可参考http://cs.hubfs.net/topic/None/73936
再定义1个测试类来试试VirtualMethodInterceptor。
type testClass() =
abstract member Test : unit -> unit
default x.Test() =
printfn "hello "
using(new UnityContainer())(fun ctner->
ctner.AddNewExtension<Interception>() |> ignore
ctner.RegisterType<testClass>(new Interceptor<VirtualMethodInterceptor>(),
new InterceptionBehavior<LogingInterceptionBehavior>()) |> ignore
showregistrations ctner
let t = ctner.Resolve<testClass>()
t.Test()
)
结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+testClass
From the logging interceptor: "Invoke method Void Test():FSI_0002+testClass at 9:30:27"
hello
From the logging interceptor: "Method Void Test():FSI_0002+testClass returned at 9:30:27"
val it : unit = ()
拦截成功。
下面略加改写原来的类定义。使接口都以virtural的情势暴露出来
type TenantStore() as x=
//do printfn "new TenantStore %A" (x.GetHashCode())
abstract Msg : unit -> unit
default x.Msg() =
printfn "Hello, it's TenantStore"
abstract Dispose : unit -> unit
default x.Dispose() =
printfn "TenantStore hase been cleaned"
interface ITenantStore with
member x.Msg() = x.Msg()
interface IDisposable with
member x.Dispose() = x.Dispose()
有些繁琐，接口实现的代码可以复用，不幸中的万幸。下面的例子中我同时测试1下多接口之间转换的情况，看看VirtualMethodInterceptor是不是也支持多接口，文档上没有明确表明。
测试代码
using(new UnityContainer())(fun ctner->
ctner.AddNewExtension<Interception>() |> ignore
ctner.RegisterType<ITenantStore, TenantStore>(new Interceptor<VirtualMethodInterceptor>(),
new InterceptionBehavior<LogingInterceptionBehavior>()) |> ignore
ctner.RegisterType<testClass>(new Interceptor<VirtualMethodInterceptor>(),
new InterceptionBehavior<LogingInterceptionBehavior>()) |> ignore
showregistrations ctner
let t = ctner.Resolve<ITenantStore>()
t.Msg()
let o = (box t) :?> IDisposable
o.Dispose()
)
TransparentProxyInterceptor
成功 结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
From the logging interceptor: "Invoke method System.Type GetType():System.Object at 9:38:47"
From the logging interceptor: "Method System.Type GetType():System.Object returned FSI_0010+TenantStore at 9:38:47"
From the logging interceptor: "Invoke method Void Msg():FSI_0002+ITenantStore at 9:38:47"
Hello, it's TenantStore
From the logging interceptor: "Method Void Msg():FSI_0002+ITenantStore returned at 9:38:47"
From the logging interceptor: "Invoke method System.Type GetType():System.Object at 9:38:47"
From the logging interceptor: "Method System.Type GetType():System.Object returned FSI_0010+TenantStore at 9:38:47"
From the logging interceptor: "Invoke method Void Dispose():System.IDisposable at 9:38:47"
TenantStore hase been cleaned
From the logging interceptor: "Method Void Dispose():System.IDisposable returned at 9:38:47"
val it : unit = ()
InterfaceInterceptor
失败 结果：
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
From the logging interceptor: "Invoke method Void Msg():FSI_0002+ITenantStore at 9:39:44"
Hello, it's TenantStore
From the logging interceptor: "Method Void Msg():FSI_0002+ITenantStore returned at 9:39:44"
System.InvalidCastException: 没法将类型为“DynamicModule.ns.Wrapped_ITenantStore_67632c824c8e42bbad5925d203ac819b”的对象强迫转换为类型“System.IDisposable”。
在 FSI_0015.it@149⑺.Invoke(UnityContainer ctner) 位置 E:WorkHellfsharp-practiseEnterpriseLibraryUnityProgram.fs:行号 157
在 Microsoft.FSharp.Core.Operators.Using[T,TResult](T resource, FSharpFunc`2 action)
在 <StartupCode$FSI_0015>.$FSI_0015.main@()
已因出错而停止
VirtualMethodInterceptor
成功 结果
Regist Type:Microsoft.Practices.Unity.IUnityContainer
Regist Type:Microsoft.Practices.Unity.InterceptionExtension.InjectionPolicy
Regist Type:FSI_0002+ITenantStore
Regist Type:FSI_0002+testClass
From the logging interceptor: "Invoke method Void Msg():FSI_0017+TenantStore at 9:42:01"
Hello, it's TenantStore
From the logging interceptor: "Method Void Msg():FSI_0017+TenantStore returned at 9:42:01"
From the logging interceptor: "Invoke method Void Dispose():FSI_0017+TenantStore at 9:42:01"
TenantStore hase been cleaned
From the logging interceptor: "Method Void Dispose():FSI_0017+TenantStore returned at 9:42:01"
val it : unit = ()
通过结果可以看到TransparentProxyInterceptor在构建的进程中多了1些步骤，翻了1下帮助文档。说这个代理是使用 TransparentProxy/RealProxy infrastructure生成的。因此速度最慢。而另两个则是通过动态代码生成的（这是甚么？反射？）。
这里可以有个小的结论了，InterfaceInterceptor最小巧实用，其他两个或多或少在使用上都要留意1下各自的特性。
再看看可替换性。
(box t) :?> TenantStore
结果
TransparentInterceptor 失败
VirtualMethodInterceptor 成功
InterfaceInterceptor 失败 和料想的1致
以上
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