.NET中AOP的几种实现方案

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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

通过代理模式实现静态代理，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;
}
}
}

输出

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

关于上面各方案的详细介绍园子里都有很好的文章，我就不班门弄斧了。

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