.NET 自带的动态代理+Expression 实现AOP

下面代码（摘抄之别处，原创在哪不知）是采用TransparentProxy和RealProxy实现对象的动态代理。碍于其使用反射掉用方法，所以就小试着将反射改成Expression以提高执行的效率。第15行就是原来代码中反射掉用方法的关键代码。

 using System.Runtime.Remoting.Proxies;
 using System.Runtime.Remoting.Messaging;
     //RealProxy
     public class MyRealProxy<T>:RealProxy
     {
         private T _target;
         public MyRealProxy(T target) : base(typeof(T))
         {
             this._target = target;
         }
        public override IMessage Invoke(IMessage msg)
        {
             PreProceede(msg);
             IMethodCallMessage callMessage = (IMethodCallMessage)msg;
             object returnValue = callMessage.MethodBase.Invoke(this._target, callMessage.Args);
             PostProceede(msg);
             return new ReturnMessage(returnValue, new object[], , null, callMessage);
         }
        public void PreProceede(IMessage msg)
        {
            Console.WriteLine("方法执行前");
        }
        public void PostProceede(IMessage msg)
        {
            Console.WriteLine("方法执行后");
        }
     }
    //TransparentProxy
    public static class TransparentProxy
    {
         public static T Create<T>()
         {
            T instance = Activator.CreateInstance<T>();
            MyRealProxy<T> realProxy = new MyRealProxy<T>(instance);
            T transparentProxy = (T)realProxy.GetTransparentProxy();
            return transparentProxy;
         }
    }

其他的辅助类

     public class User
     {
         public string Name { get; set; }
         public string PassWord { get; set; }
     }

     public interface IUserProcessor
     {
         void RegUser(User user);
     }

     public class UserProcessor : MarshalByRefObject, IUserProcessor
     {
         public void RegUser(User user)
         {
             Console.WriteLine("Already registered.");
         }

         public string RegUser2(User user)
         {
             Console.WriteLine("Already registered.");
             return "OK";
         }
     }

     public class RemotingProxy
     {
         public void Execute()
         {
             try
             {
                 User user = new User() { Name = "HK", PassWord = "" };
                 UserProcessor userprocessor = TransparentProxy.Create<UserProcessor>();
                 userprocessor.RegUser(user);
                 Console.WriteLine(userprocessor.RegUser2(user));
             }
             catch (Exception ex)
             {
                 throw ex;
             }

         }
     }

将15行替换为如下Expression实现的代码。