在本文之前的前几篇浅谈.NET编译时注入（C#-->IL）、浅谈VS编译自定义编译任务—MSBuild Task(csproject)、编译时MSIL注入--实践Mono Cecil(1)已经讨论了MSBuild和Mono.Cicel。在这里我们将会利用它来实现一个简单的编译时AOP注入机制（这里所说的编译时是指c#到MSIL的预编译过程）。我更倾向于像EL（微软企业库框架）这类动态AOP。编译时AOP有PostSharp这种被称之为静态AOP框架，其优势在于直接代码语句，性能更好，它不需要我们多余的代码，像EL这种动态AOP，一般我们是不能直接new一个对象，需要容器（Container），在一些你的框架应用种，有时就需要使用者了解，再入我们对于WinForm、WebForm等.net平台上主流的基于微软事件机制的框架，事件方法的截获，往往我们需要改变、包装。在这时静态AOP就显出了他的优势。
Class Diagram：
1：IMethodInject：Interface，拥有Executeing，Exceptioned，ExecuteSuccess三个契约为别为执行前，异常，成功。它们都有公同的参数类型：MethodExecutionEventArgs
Executeing：返回值为bool类型，将决定是否继续执行方法体。Exceptioned：属性Eeption代表发生的异常信息，返回值ExceptionStrategy（取值：Handle, ReThrow, ThrowNew）决定异常处理机制，Handle已处理并忽略，ReThrow重新抛出，ThrowNew抛出一个包装后的来源于MethodExecutionEventArgs 的Exception。ExecuteSuccess，对于拥有返回值的方法，可以修改MethodExecutionEventArgs 的ReturnValue，修改返回值。最后MethodExecutionEventArgs的Order决定多个Attribute的注入先后，即方法截获的先后顺序。
1：MethodInterceptBase：针对于方法Attribute标签，实现方法截获
[AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
public class MethodInterceptBase : Attribute, IMethodInject
{
public int Order
{
get;
set;
}
#region IMethodInject Members
public virtual bool Executeing(MethodExecutionEventArgs args)
{
return true;
}
public virtual ExceptionStrategy Exceptioned(MethodExecutionEventArgs args)
{
return ExceptionStrategy.ReThrow;
}
public virtual void ExecuteSuccess(MethodExecutionEventArgs args)
{
}
#endregion
}
2：MatchedMethodInterceptBase：和上面方法之上的MethodInterceptBase大体一致，区别在于其应用于class之上，属性Rule为截获方法匹配（应用于多个方法之上相同截获），支持*匹配。
[AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
public class MatchedMethodInterceptBase : Attribute, IMethodInject
{
public int Order
{
get;
set;
}
public string Rule
{
get;
set;
}
#region IMethodInject Members
public virtual bool Executeing(MethodExecutionEventArgs args)
{
return true;
}
public virtual ExceptionStrategy Exceptioned(MethodExecutionEventArgs args)
{
return ExceptionStrategy.ReThrow;
}
public virtual void ExecuteSuccess(MethodExecutionEventArgs args)
{
}
#endregion
}
3：PropertyInterceptBase：实现属性的注入，其属性Action（enum PropertyInterceptAction：None Get, Set）指注入属性的get或者Set；
[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
public class PropertyInterceptBase : Attribute, IMethodInject
{
public PropertyInterceptAction Action
{
get;
set;
}
public int Order
{
get;
set;
}
#region IMethodInject Members
public virtual bool Executeing(MethodExecutionEventArgs args)
{
return true;
}
public virtual ExceptionStrategy Exceptioned(MethodExecutionEventArgs args)
{
return ExceptionStrategy.ReThrow;
}
public virtual void ExecuteSuccess(MethodExecutionEventArgs args)
{
}
#endregion
}
其上默认都是Executeing继续执行，Exceptioned为抛出不处理，成功不修改result。
下面是一个简单测试Code：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using Green.AOP;
namespace Test
{
// [TestAOP2Attribute(Rule = "TestMethod1*")]
public class Class1
{
// [TestAOPPropertyAttribute(Action = PropertyInterceptAction.Set)]
[TestAOPPropertyGetAttribute(Action = PropertyInterceptAction.Get)]
public testStrust TestProperty
{
get;
set;
}
[Obsolete()]
public static void Main(string[] args)
{
try
{
var y = new Class1();
// y.TestProperty = DateTime.Now;
Console.WriteLine(y.TestProperty);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
// new Class1().TestMethod1(1, 2, null);
Console.Read();
//throw new Exception("exfffffffffffffffffffff");
}
//[TestAOPAttribute(Order=1)]
//[TestAOP1Attribute(TestProperty = 1, Template = "sdsdsd",Order=0)]
public Class1 TestMethod1(int i, int j, Class1 c)
{
Console.WriteLine("ok");
return new Class1();
}
}
public class TestAOPPropertyGetAttribute : Green.AOP.PropertyInterceptBase
{
#region IMethodInject Members
public override bool Executeing(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine("------------------" + args);
Console.WriteLine(args.Instance);
Console.WriteLine(args.Method);
Console.WriteLine(this.GetType() + ":" + "Executeing");
return true;
}
public override Green.AOP.ExceptionStrategy Exceptioned(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Exceptioned");
return Green.AOP.ExceptionStrategy.ReThrow;
}
public override void ExecuteSuccess(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine("-----------");
Console.WriteLine(this.GetType() + ":" + "ExecuteSuccess" + "--result:" + args.ReturnValue);
}
#endregion
}
public class TestAOPPropertyAttribute : Green.AOP.PropertyInterceptBase
{
#region IMethodInject Members
public override bool Executeing(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(args.Instance);
Console.WriteLine(args.Method);
Console.WriteLine(this.GetType() + ":" + "Executeing");
return true;
}
public override Green.AOP.ExceptionStrategy Exceptioned(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Exceptioned");
return Green.AOP.ExceptionStrategy.Handle;
}
public override void ExecuteSuccess(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "ExecuteSuccess");
}
#endregion
}
public class TestAOP2Attribute : Green.AOP.MatchedMethodInterceptBase
{
#region IMethodInject Members
public override bool Executeing(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(args.Instance);
Console.WriteLine(args.Method);
Console.WriteLine(this.GetType() + ":" + "Executeing");
return true;
}
public override Green.AOP.ExceptionStrategy Exceptioned(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Exceptioned");
return Green.AOP.ExceptionStrategy.Handle;
}
public override void ExecuteSuccess(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "ExecuteSuccess");
}
#endregion
#region IMethodInject Members
public bool Match(System.Reflection.MethodBase method)
{
return true;
}
#endregion
}
//[AttributeUsage(AttributeTargets.Method)]
public class TestAOPAttribute : Green.AOP.MethodInterceptBase
{
#region IMethodInject Members
public override bool Executeing(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Executeing");
return true;
}
public override Green.AOP.ExceptionStrategy Exceptioned(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Exceptioned");
return Green.AOP.ExceptionStrategy.Handle;
}
public override void ExecuteSuccess(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "ExecuteSuccess");
}
#endregion
#region IMethodInject Members
public bool Match(System.Reflection.MethodBase method)
{
return true;
}
#endregion
}
[AttributeUsage(AttributeTargets.Method)]
public class TestAOP1Attribute : Attribute, Green.AOP.IMethodInject
{
public int Order
{
get;
set;
}
public int TestProperty
{
get;
set;
}
public string Template
{
get;
set;
}
#region IMethodInject Members
public bool Executeing(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Executeing");
return true;
}
public Green.AOP.ExceptionStrategy Exceptioned(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "Exceptioned");
return Green.AOP.ExceptionStrategy.Handle;
}
public void ExecuteSuccess(Green.AOP.MethodExecutionEventArgs args)
{
Console.WriteLine(this.GetType() + ":" + "ExecuteSuccess");
}
#endregion
#region IMethodInject Members
public bool Match(System.Reflection.MethodBase method)
{
return true;
}
#endregion
}
}
注意测试有两种方式（由于没有安装包）：
1：先重编译测试项目，运行ConsoleApplication2（在属性中修改控制台其实参数）。在查看测试项目。
2：将项目ConsoleApplication2修改为类库，在添加修改csprojec信息，Task位于Green.AOP.MyBuildTask，具体可以参见上一篇浅谈VS编译自定义编译任务—MSBuild Task(csproject)。
在后续将会从简单Demo分析实现原理。
作者：破 狼
出处：http://www.cnblogs.com/whitewolf/
本文版权归作者，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。该文章也同时发布在我的独立博客中-个人独立博客、博客园--破狼和51CTO--破狼。http://www.cnblogs.com/whitewolf/archive/2011/08/09/2132217.html