[AOP]Crosscutting Concerns實作

Crosscutting Concerns 使用System.Runtime.Remoting.Proxies.RealProxy類別來實作

一，說明Hello這類別就是用來繼承MarshalByRefObject類別，在AOP中表示Pointcut。
Hello.vb

 
Public Class Hello
    Inherits MarshalByRefObject
End Class

二，說明IHello這類別就是定義一個Interface，在AOP中表示Weave。
IHello.vb

 
Public Interface IHello
    Sub hello(ByVal name As String)
End Interface

三，說明LogHandler這類別就是用來做動態Proxy Pattern，繼承RealProxy類別，在AOP中表示Advices。
LogHandler.vb

 
Imports System.Runtime.Remoting.Proxies
Imports System.Runtime.Remoting.Messaging
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Services

Public Class LogHandler
    Inherits RealProxy

    Private myMarshalByRefObject As MarshalByRefObject

    Public Sub New(ByVal myType As Type)
        MyBase.New(myType)
        myMarshalByRefObject = CType(Activator.CreateInstance(myType), MarshalByRefObject)
    End Sub

    Public Overrides Function Invoke(ByVal myIMessage As IMessage) As IMessage
        Dim calls As IMethodCallMessage = myIMessage
        Dim back As IMethodReturnMessage = Nothing

        Console.WriteLine("呼叫方法的名稱:" + calls.MethodName)

        back = RemotingServices.ExecuteMessage(myMarshalByRefObject, calls)

        Console.WriteLine("顯示的結果:" + back.ReturnValue.ToString())

        Return back
    End Function
End Class

四，說明HelloSpeaker這類別就是用來這類別就是用來繼承Hello類別並實作IHello介面，在AOP中表示Joinpoint。
HelloSpeaker.vb

 
Public Class HelloSpeaker
    Inherits Hello
    Implements IHello

    Public Sub hello(name As String) Implements IHello.hello
        Console.WriteLine("Hello：" + name)
    End Sub

End Class

五，執行
ProxyDemo.vb

 
Module ProxyDemo
    Sub Main()
        Dim proxy As LogHandler = New LogHandler(New HelloSpeaker().GetType())
        Dim Hello As IHello = proxy.GetTransparentProxy()
        Hello.hello("123")
        Console.ReadKey()
    End Sub
End Module