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View Code
- [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
- }
- 复制代码
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。
- View Code
- [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
- }
- 复制代码
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；View Code
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：
- View 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
- }
- }
- 复制代码
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。
- [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
- }
- 复制代码
本文转自 破狼 51CTO博客，原文链接：http://blog.51cto.com/whitewolfblog/835181 ，如需转载请自行联系原作者
