面向切面编程

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using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System;

using System.Runtime.Remoting.Messaging;

using System;

using System.Runtime.Remoting;

using System.Runtime.Remoting.Proxies;

using System.Runtime.Remoting.Messaging;

using System.Runtime.Remoting.Services;

using System.Runtime.Remoting.Activation;

using EnterpriseServerBase.Aop;



namespace EnterpriseServerBase.Aop

{

    public class AopControlProxyFactory : IAopProxyFactory

    {

        #region IAopProxyFactory 成员



        public AopProxyBase CreateAopProxyInstance(MarshalByRefObject obj, Type type)

        {

            return new AopControlProxy(obj, type);

        }



        #endregion

    }



    //自定义真实代理

    public class AopControlProxy : AopProxyBase

    {

        public AopControlProxy(MarshalByRefObject obj, Type type)

            : base(obj, type)

        {

        }



        public override void PreProcess(IMessage requestMsg)

        {

            Debug.Write("Begin Aop !");

        }



        public override void PostProcess(IMessage requestMsg, IMessage Respond)

        {

            Debug.Write("End Aop !");

        }

    }



    [AopProxyAttribute(typeof(AopControlProxyFactory))] //将自己委托给AOP代理AopControlProxy

    public class Example : ContextBoundObject //放到特定的上下文中，该上下文外部才会得到该对象的透明代理

    {

        private string name;



        public Example(string a)

        {

            this.name = a;

        }





        [MethodAopSwitcher(true)]

        public void say_hello()

        {

            Debug.WriteLine("hello ! " + name);

        }



        public void sayByeBye()

        {

            Debug.WriteLine("Bye ! " + name);

        }

    }

}



namespace EnterpriseServerBase.Aop

{

    /// <summary>

    /// IAopOperator AOP操作符接口，包括前处理和后处理

    /// 2005.04.12

    /// </summary>

    public interface IAopOperator

    {

        void PreProcess(IMessage requestMsg);

        void PostProcess(IMessage requestMsg, IMessage Respond);

    }



    /// <summary>

    /// IAopProxyFactory 用于创建特定的Aop代理的实例，IAopProxyFactory的作用是使AopProxyAttribute独立于具体的AOP代理类。

    /// </summary>

    public interface IAopProxyFactory

    {

        AopProxyBase CreateAopProxyInstance(MarshalByRefObject obj, Type type);

    }



}



namespace EnterpriseServerBase.Aop

{

    /// <summary>

    /// AopProxyBase 所有自定义AOP代理类都从此类派生，覆写IAopOperator接口，实现具体的前/后处理 。

    /// 2005.04.12

    /// </summary>

    public abstract class AopProxyBase : RealProxy, IAopOperator

    {

        private readonly MarshalByRefObject target; //默认透明代理



        public AopProxyBase(MarshalByRefObject obj, Type type)

            : base(type)

        {

            this.target = obj;

        }



        #region Invoke

        public override IMessage Invoke(IMessage msg)

        {

            bool useAspect = false;

            IMethodCallMessage call = (IMethodCallMessage)msg;



            //查询目标方法是否使用了启用AOP的MethodAopSwitcherAttribute

            foreach (Attribute attr in call.MethodBase.GetCustomAttributes(false))

            {

                MethodAopSwitcherAttribute mehodAopAttr = attr as MethodAopSwitcherAttribute;

                if (mehodAopAttr != null)

                {

                    if (mehodAopAttr.UseAspect)

                    {

                        useAspect = true;

                        break;

                    }

                }

            }



            if (useAspect)

            {

                this.PreProcess(msg);

            }



            //如果触发的是构造函数，此时target的构建还未开始

            IConstructionCallMessage ctor = call as IConstructionCallMessage;

            if (ctor != null)

            {

                //获取最底层的默认真实代理

                RealProxy default_proxy = RemotingServices.GetRealProxy(this.target);



                default_proxy.InitializeServerObject(ctor);

                MarshalByRefObject tp = (MarshalByRefObject)this.GetTransparentProxy(); //自定义的透明代理 this



                return EnterpriseServicesHelper.CreateConstructionReturnMessage(ctor, tp);

            }



            IMethodReturnMessage result_msg = RemotingServices.ExecuteMessage(this.target, call); //将消息转化为堆栈，并执行目标方法，方法完成后，再将堆栈转化为消息



            if (useAspect)

            {

                this.PostProcess(msg, result_msg);

            }



            return result_msg;



        }

        #endregion



        #region IAopOperator 成员



        public abstract void PreProcess(IMessage requestMsg);

        public abstract void PostProcess(IMessage requestMsg, IMessage Respond);

        #endregion



    }



}





//3. AopProxyAttribute　AOP代理特性



//****************************** AopProxyAttribute　 ************************************

namespace EnterpriseServerBase.Aop

{

    /// <summary>

    /// AopProxyAttribute

    /// AOP代理特性，如果一个类想实现具体的AOP，只要实现AopProxyBase和IAopProxyFactory，然后加上该特性即可。

    /// 2005.04.11

    /// </summary>



    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]

    public class AopProxyAttribute : ProxyAttribute

    {

        private IAopProxyFactory proxyFactory = null;



        public AopProxyAttribute(Type factoryType)

        {

            this.proxyFactory = (IAopProxyFactory)Activator.CreateInstance(factoryType);

        }



        #region CreateInstance

        /// <summary>

        /// 获得目标对象的自定义透明代理

        /// </summary>

        public override MarshalByRefObject CreateInstance(Type serverType)//serverType是被AopProxyAttribute修饰的类

        {

            //未初始化的实例的默认透明代理

            MarshalByRefObject target = base.CreateInstance(serverType); //得到位初始化的实例（ctor未执行）

            object[] args = { target, serverType };

            //AopProxyBase rp = (AopProxyBase)Activator.CreateInstance(this.realProxyType ,args) ; //Activator.CreateInstance在调用ctor时通过了代理，所以此处将会失败



            //得到自定义的真实代理

            AopProxyBase rp = this.proxyFactory.CreateAopProxyInstance(target, serverType);//new AopControlProxy(target ,serverType) ;

            return (MarshalByRefObject)rp.GetTransparentProxy();

        }

        #endregion

    }

}

//4 .MethodAopSwitcherAttribute.cs



// /**************************** MethodAopSwitcherAttribute.cs *************************





namespace EnterpriseServerBase.Aop

{

    /// <summary>

    /// MethodAopSwitcherAttribute 用于决定一个被AopProxyAttribute修饰的class的某个特定方法是否启用截获 。

    /// 创建原因：绝大多数时候我们只希望对某个类的一部分Method而不是所有Method使用截获。

    /// 使用方法：如果一个方法没有使用MethodAopSwitcherAttribute特性或使用MethodAopSwitcherAttribute(false)修饰，

    ///　 都不会对其进行截获。只对使用了MethodAopSwitcherAttribute(true)启用截获。

    /// 2005.05.11

    /// </summary>

    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]

    public class MethodAopSwitcherAttribute : Attribute

    {

        private bool useAspect = false;



        public MethodAopSwitcherAttribute(bool useAop)

        {

            this.useAspect = useAop;

        }



        public bool UseAspect

        {

            get

            {

                return this.useAspect;

            }

        }

    }

}