Shulou(Shulou.com)06/01 Report--

AOP introduction

Aspect-oriented programming (Aspect Oriented Programming, abbreviated as AOP) is a technology that realizes the unified maintenance of program functions through pre-compilation and runtime dynamic agents.

AOP is the continuation of OOP and is a hot spot in software development.

Commonly used for:

Authentication

Caching

Lazy loading

Transactions

Basic principles of AOP

Ordinary class

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Class Person: MarshalByRefObject

{

Public string Say ()

{

Const string str = "Person's say is called"

Console.WriteLine (str)

Return str

}

}

Proxy class

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Public class Proxy: RealProxy where T: new ()

{

Private object _ obj

Public Proxy (object obj)

Base (typeof (T))

{

_ obj = obj

}

Public override IMessage Invoke (IMessage msg)

{

Console.WriteLine ("{0}: before Invoke", DateTime.Now)

Var ret = ((IMethodCallMessage) msg) .MethodBase.Invoke (_ obj, null)

Console.WriteLine ("{0}: after Invoke", DateTime.Now)

Return new ReturnMessage (ret, null, 0, null, null)

}

}

Execution

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Static void Main (string [] args)

{

Var per = new Proxy (new Person ()) .GetTransparentProxy () as Person

If (per! = null)

{

Var str = per.Say ()

Console.WriteLine ("return value:" + str)

}

Console.ReadKey ()

}

AOP framework

AOP has dynamic proxies and static IL weaving.

This section mainly introduces the dynamic proxy mode, static can refer to PostSharp.

Castle Core

Principle: the essence is to create a proxy class that inherits the original class. Override virtual method to realize AOP function.

Just quote:

Install-Package Castle.Core

(over version 2.5 of Castle, content in Castle.DynamicProxy2.dll has been integrated into Castle.Core.dll.)

Simple Class

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Public abstract class Person

{

Public virtual void SayHello ()

{

Console.WriteLine ("I am the {0} method", "SayHello")

}

Public virtual void SayName (string name)

{

Console.WriteLine ("I am the {0} method, parameter values: {1}", "SayName", name)

}

Public abstract void AbstactSayOther ()

Public void SayOther ()

{

Console.WriteLine ("I am the {0} method", "SayOther")

}

}

Interceptor

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Public class SimpleInterceptor: StandardInterceptor

{

Protected override void PreProceed (IInvocation invocation)

{

Console.WriteLine ("before the interceptor calls the method, the method name is: {0}." , invocation.Method.Name)

}

Protected override void PerformProceed (IInvocation invocation)

{

Console.WriteLine ("the interceptor starts calling the method with the name: {0}." , invocation.Method.Name)

Var attrs = invocation.MethodInvocationTarget.Attributes.HasFlag (MethodAttributes.Abstract); / / filter abstract method

If (! attrs)

{

Base.PerformProceed (invocation); / / the real method invocation.Proceed () will be called here

}

}

Protected override void PostProceed (IInvocation invocation)

{

Console.WriteLine ("after the interceptor calls the method, the method name is: {0}." , invocation.Method.Name)

}

}

Main

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Static void Main (string [] args)

{

Var generator = new ProxyGenerator (); / / instantiate [proxy class generator]

Var interceptor = new SimpleInterceptor (); / / instantiate [interceptor]

/ / use [proxy Class Builder] to create a Person object instead of using the new keyword to instantiate

Var person = generator.CreateClassProxy (interceptor)

Console.WriteLine ("current type: {0}, parent type: {1}", person.GetType (), person.GetType () .BaseType)

Console.WriteLine ()

Person.SayHello () / / intercept

Console.WriteLine ()

Person.SayName ("Never, C"); / / interception

Console.WriteLine ()

Person.SayOther (); / / normal method, cannot be intercepted

Person.AbstactSayOther (); / / Abstract methods that can intercept

Console.ReadLine ()

}

Castle Windsor

Characteristic AOP

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Public interface IPerson

{

Void Say ()

}

[Interceptor (typeof (LogInterceptor))]

Public class Person: IPerson

{

Public void Say ()

{

Console.WriteLine ("Person's Say Method is called!")

}

}

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Public class LogInterceptor: IInterceptor

{

Public void Intercept (IInvocation invocation)

{

Console.WriteLine ("{0}: before intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

Invocation.Proceed ()

Console.WriteLine ("{0}: after intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

}

}

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Static void Main (string [] args)

{

Using (var container = new WindsorContainer ())

{

Container.Register (Component.For ())

Container.Register (Component.For ())

Var person = container.Resolve ()

Person.Say ()

}

Console.ReadKey ()

}

Non-invasive AOP

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Public interface IPerson

{

Void Say ()

}

Public class Person: IPerson

{

Public void Say ()

{

Console.WriteLine ("Person's Say Method is called!")

}

}

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Internal static class LogInterceptorRegistrar

{

Public static void Initialize (WindsorContainer container)

{

Container.Kernel.ComponentRegistered + = Kernel_ComponentRegistered

}

Private static void Kernel_ComponentRegistered (string key, IHandler handler)

{

Handler.ComponentModel.Interceptors.Add (new InterceptorReference (typeof (LogInterceptor)

}

}

Public class LogInterceptor: IInterceptor

{

Public void Intercept (IInvocation invocation)

{

Console.WriteLine ("{0}: before intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

Invocation.Proceed ()

Console.WriteLine ("{0}: after intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

}

}

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Static void Main (string [] args)

{

Using (var container = new WindsorContainer ())

{

Container.Register (Component.For ()); / / inject the interceptor first

LogInterceptorRegistrar.Initialize (container)

Container.Register (Component.For ())

Var person = container.Resolve ()

Person.Say ()

}

Console.ReadKey ()

}

Autofac

Install-Package Autofac.Aop

Bind through property label

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Class LogInterceptor: IInterceptor

{

Public void Intercept (IInvocation invocation)

{

Console.WriteLine ("{0}: before intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

Invocation.Proceed ()

Console.WriteLine ("{0}: after intercepting {1} method {2},", DateTime.Now.ToString ("O"), invocation.InvocationTarget.GetType () .BaseType, invocation.Method.Name)

}

}

Public interface IPerson

{

Void Say ()

}

[Intercept (typeof (LogInterceptor))]

Public class Person: IPerson

{

Public void Say ()

{

Console.WriteLine ("Person's Say Method is called!")

}

}

Enable interceptor execution

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Static void Main (string [] args)

{

Var builder = new ContainerBuilder ()

Builder.RegisterType (). As (). EnableInterfaceInterceptors ()

Builder.RegisterType ()

Using (var container = builder.Build ())

{

Container.Resolve () .Say ()

}

Console.ReadLine ()

}

Or adopt a non-invasive approach (it is still possible to remove the features on class)

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Static void Main (string [] args)

{

Var builder = new ContainerBuilder ()

Builder.RegisterType (). As (). EnableInterfaceInterceptors (). InterceptedBy (typeof (LogInterceptor))

Builder.RegisterType ()

Using (var container = builder.Build ())

{

Container.Resolve () .Say ()

}

Console.ReadLine ()

}

Unity

Unity provides three interceptors by default: TransparentProxyInterceptor, InterfaceInterceptor, and VirtualMethodInterceptor.

TransparentProxyInterceptor: the proxy implementation is based on .NET Remoting technology, which intercepts all functions of the object. The disadvantage is that the intercepted type must be derived from MarshalByRefObject.

InterfaceInterceptor: only one interface can be intercepted. The advantage is that it can be intercepted as long as the target type implements the specified interface.

VirtualMethodInterceptor: intercept the virtual function. The disadvantage is that if the intercepted type does not have a virtual function, it cannot be intercepted. At this time, if the type implements a specific interface, it can be used instead.

Install-Package Unity.Interception

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Public class MyHandler: ICallHandler

{

Public int Order {get; set;} / / this is a member of ICallHandler, indicating the order of execution

Public IMethodReturn Invoke (IMethodInvocation input, GetNextHandlerDelegate getNext)

{

Console.WriteLine ("before method execution")

/ / pre-execution processing of the insert method before this

Var retvalue = getNext () (input, getNext); / / execute the method here

/ / after that, the processing after the execution of the insert method

Console.WriteLine ("after method execution")

Return retvalue

}

}

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Public class MyHandlerAttribute: HandlerAttribute

{

Public override ICallHandler CreateHandler (IUnityContainer container)

{

Return new MyHandler (); / / returns MyHandler

}

}

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Public interface IPerson

{

Void Say ()

}

[MyHandler]

Public class Person: IPerson

{

Public virtual void Say ()

{

Console.WriteLine ("Person's Say Method is called!")

}

}

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Static void Main (string [] args)

{

Using (var container = new UnityContainer ())

{

Container.AddNewExtension ()

/ / 1.TransparentProxyInterceptor

/ container.Configure () .SetInterceptorFor (new TransparentProxyInterceptor ())

/ / 2.InterfaceInterceptor (use 1, 2, 3, this is the least intrusive)

Container.Configure () .SetInterceptorFor (new InterfaceInterceptor ()

/ / 3.VirtualMethodInterceptor

/ container.Configure () .SetInterceptorFor (new VirtualMethodInterceptor ())

Container.RegisterType ()

Container.Resolve () .Say ()

}

Console.ReadKey ()

}

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