.NET中AOP的几种实现方案

AOP在.NET中的应用，个人也属于学习阶段，欢迎大家拍砖！

本文的例子模拟用户注册的场景，主要通过代码演示几种方案的实现方式。

静态代理

通过装饰模式实现静态代理，大家一看代码基本就明白了。

用户注册接口和实现

public interface IUserProcessor
{
    void RegUser(User user);
}
public class UserProcessor : IUserProcessor
{
    public  void RegUser(User user)
    {
        Console.WriteLine("用户已注册。Name:{0},PassWord:{1}", user.Name, user.PassWord);
    }
}

通过静态编写代码的方式，装饰上面的用户注册

public class UserProcessorDecorator:IUserProcessor
    {
        public IUserProcessor UserProcessor { get; set; }
        public UserProcessorDecorator(IUserProcessor userprocessor)
        {
            UserProcessor = userprocessor;
        }
        public  void RegUser(User user)
        {
            PreProceed(user);
            UserProcessor.RegUser(user);
            PostProceed(user);
        }
        public void PreProceed(User user)
        {
            Console.WriteLine("方法执行前");
        }

        public void PostProceed(User user)
        {
            Console.WriteLine("方法执行后");
        }
    }

客户端调用

public class Client
{
    public static void Run()
    {
        try
        {
            User user = new User() { Name = "lee", PassWord = "123123123123" };
            IUserProcessor userprocessor = new UserProcessorDecorator(new UserProcessor());
            userprocessor.RegUser(user);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }
}

输出

方法执行前
用户已注册。Name:lee,PassWord:123123123123
方法执行后

动态代理

1、使用.Net Remoting/RealProxy

采用TransparentProxy和RealProxy实现对象的代理，实现思路如下：Client -TransparentProxy - RealProxy - Target Object

下面实现自定义的TransparentProxy和RealProxy

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[0], 0, 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;
        }
   }

用户注册接口和实现

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

  public class UserProcessor : MarshalByRefObject, IUserProcessor
  {
      public void RegUser(User user)
      {
          Console.WriteLine("用户已注册。");
      }
  }

客户端调用

public class Client
   {
       public static void Run()
       {
           try
           {
               User user = new User() { Name = "lee", PassWord = "123123123123" };
               UserProcessor userprocessor = TransparentProxy.Create<UserProcessor>();
               userprocessor.RegUser(user);
           }
           catch (Exception ex)
           {
               throw ex;
           }
       }
   }

输出

方法执行前
用户已注册。Name:lee,PassWord:123123123123
方法执行后

2、使用EntLib\PIAB

自定义CallHandler，这里定义两个CallHandler分别用于参数检查和日志记录。

using Microsoft.Practices.Unity.InterceptionExtension;

public class UserHandler:ICallHandler
    {
        public int Order { get; set; }
        public IMethodReturn Invoke(IMethodInvocation input, GetNextHandlerDelegate getNext)
        {
            User user = input.Inputs[0] as User;
            if (user.PassWord.Length < 10)
            {
                return input.CreateExceptionMethodReturn(new UserException("密码长度不能小于10位"));
            }
            Console.WriteLine("参数检测无误");
            return getNext()(input, getNext);
        }
    }

    public class LogHandler:ICallHandler
    {
        public int Order { get; set; }
        public IMethodReturn Invoke(IMethodInvocation input, GetNextHandlerDelegate getNext)
        {
            User user = input.Inputs[0] as User;
            Log log = new Log() { Message = string.Format("RegUser:Username:{0},Password:{1}", user.Name, user.PassWord), Ctime = DateTime.Now };
            Console.WriteLine("日志已记录，Message:{0},Ctime:{1}",log.Message,log.Ctime);
            var messagereturn  = getNext()(input, getNext);
            return messagereturn;
        }
    }

定义对应的HandlerAttribute

using Microsoft.Practices.Unity.InterceptionExtension;
using Microsoft.Practices.Unity;

    public class UserHandlerAttribute : HandlerAttribute
    {
        public override ICallHandler CreateHandler(IUnityContainer container)
        {
            ICallHandler handler = new UserHandler(){Order=this.Order};
            return handler;
        }
    }

    public  class LogHandlerAttribute:HandlerAttribute
    {
        public int Order { get; set; }
        public override ICallHandler CreateHandler(IUnityContainer container)
        {
            return new LogHandler() { Order = this.Order };
        }
    }

用户注册接口和实现，这里通过为接口添加attribute的方式实现。order值表示执行顺序，值小的先执行。

[LogHandlerAttribute(Order=2)]
[UserHandlerAttribute(Order=1)]
public interface IUserProcessor
{
     void RegUser(User user);
}

public class UserProcessor : MarshalByRefObject,IUserProcessor
{
    public  void RegUser(User user)
    {
        Console.WriteLine("用户已注册。");
    }
}

客户端调用

using Microsoft.Practices.EnterpriseLibrary.PolicyInjection;

    public class Client
    {
        public static void Run()
        {
            try
            {
                User user = new User() { Name = "lee", PassWord = "123123123123" };
                UserProcessor userprocessor = PolicyInjection.Create<UserProcessor>();
                userprocessor.RegUser(user);
            }
            catch(Exception ex)
            {
                throw ex;
            }
        }
    }

输出：

参数检测无误
日志已记录，Message:RegUser:Username:lee,Password:123123123123,Ctime:2010-12-22
6:14:59
用户已注册。

3、使用Castle\DynamicProxy

自定义Interceptor

public class MyInterceptor : IInterceptor
   {
       public void Intercept(IInvocation invocation)
       {
           PreProceed(invocation);
           invocation.Proceed();
           PostProceed(invocation);
       }
       public void PreProceed(IInvocation invocation)
       {
           Console.WriteLine("方法执行前");
       }

       public void PostProceed(IInvocation invocation)
       {
           Console.WriteLine("方法执行后");
       }
   }

用户注册接口和实现

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

   public class UserProcessor : IUserProcessor
   {
       public virtual void RegUser(User user)
       {
           Console.WriteLine("用户已注册。Name:{0},PassWord:{1}", user.Name, user.PassWord);
       }
   }

客户端调用

public class Client
   {
       public static void Run()
       {
           try
           {
               ProxyGenerator generator = new ProxyGenerator();
               MyInterceptor interceptor = new MyInterceptor();
               UserProcessor userprocessor = generator.CreateClassProxy<UserProcessor>(interceptor);
               User user= new User() { Name = "lee", PassWord = "123123123123" };
               userprocessor.RegUser(user);
           }
           catch (Exception ex)
           {
               throw ex;
           }
       }
   }