【转】.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。碍于其使用反射调用方法，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调用方法的关键代码。

 1 using System.Runtime.Remoting.Proxies;2 using System.Runtime.Remoting.Messaging;3     //RealProxy4     public class MyRealProxy<T>:RealProxy5     {6         private T _target;7         public MyRealProxy(T target) : base(typeof(T))8         {9             this._target = target;
10         }
11        public override IMessage Invoke(IMessage msg)
12        {
13             PreProceede(msg);
14             IMethodCallMessage callMessage = (IMethodCallMessage)msg;
15             object returnValue = callMessage.MethodBase.Invoke(this._target, callMessage.Args);
16             PostProceede(msg);
17             return new ReturnMessage(returnValue, new object[0], 0, null, callMessage);
18         }
19        public void PreProceede(IMessage msg)
20        {
21            Console.WriteLine("方法执行前");
22        }
23        public void PostProceede(IMessage msg)
24        {
25            Console.WriteLine("方法执行后");
26        }
27     }
28    //TransparentProxy
29    public static class TransparentProxy
30    {
31         public static T Create<T>()
32         {
33            T instance = Activator.CreateInstance<T>();
34            MyRealProxy<T> realProxy = new MyRealProxy<T>(instance);
35            T transparentProxy = (T)realProxy.GetTransparentProxy();
36            return transparentProxy;
37         }
38    }

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其他的辅助类

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 1     public class User 2     {3         public string Name { get; set; }4         public string PassWord { get; set; }5     }6 7     public interface IUserProcessor8     {9         void RegUser(User user);
10     }
11 
12     public class UserProcessor : MarshalByRefObject, IUserProcessor
13     {
14         public void RegUser(User user)
15         {
16             Console.WriteLine("Already registered.");
17         }
18 
19         public string RegUser2(User user)
20         {
21             Console.WriteLine("Already registered.");
22             return "OK";
23         }
24     }
25 
26     public class RemotingProxy
27     {
28         public void Execute()
29         {
30             try
31             {
32                 User user = new User() { Name = "HK", PassWord = "12345" };
33                 UserProcessor userprocessor = TransparentProxy.Create<UserProcessor>();
34                 userprocessor.RegUser(user);
35                 Console.WriteLine(userprocessor.RegUser2(user));
36             }
37             catch (Exception ex)
38             {
39                 throw ex;
40             }
41 
42         }
43     }

将15行替换为如下Expression实现的代码。