背景

什么叫“动态代理”，代理模式我们都知道，动态代理就是动态生成的代理（采用Emit）。

重量级的ORM和IOC产品离不开动态代理，作为开发人员，多数情况不用关注动态代理的内部实现机制，但是了解其一般的规律和模式还是有必要的，比如：虽然你开发期间采用了POCO，因为开启了动态代理，运行期间则不是POCO。

本文简单描述了5种代理生成模式和1种Mixin模式，最后给出一个示例。

公共代码

这里先给出公共代码。

1     public interface IPlayable 2     { 3         void Play(); 4     } 5  6     public class Animal : IPlayable 7     { 8         public virtual void Play() 9         {10             Console.WriteLine("Animal.Play");11         }12     }13 14     public class Dog : Animal15     {16         public override void Play()17         {18             Console.WriteLine("Dog.Play");19         }20     }21 22     public interface IRunable23     {24         void Run();25     }26 27     public class RunAbility : IRunable28     {29         public void Run()30         {31             Console.WriteLine("RunAbility.Run");32         }33     }34 35     public class AnimalInterceptor : IInterceptor36     {37         public void Intercept(IInvocation invocation)38         {39             Console.WriteLine("Before AnimalInterceptor.Intercept");40             if (invocation.InvocationTarget != null)41             {42                 invocation.Proceed();43             }44             Console.WriteLine("After AnimalInterceptor.Intercept");45         }46     }

5种代理模式

第一种：ClassProxy

代码示例

1             { 2                 Console.WriteLine("\n*************ClassProxy*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var animal = generator.CreateClassProxy
     
      (new AnimalInterceptor()); 5                 animal.Play(); 6  7                 Console.WriteLine(animal.GetType()); 8                 Console.WriteLine(animal.GetType().BaseType); 9 10                 var compositeField = animal.GetType().GetField("__target");11                 Console.WriteLine(compositeField);12 13                 foreach (var interfaceType in animal.GetType().GetInterfaces())14                 {15                     Console.WriteLine(interfaceType);16                 }17             }

运行结果

动态代理类图

等待上传中。

第二种：ClassProxyWithTarget

代码示例

1             { 2                 Console.WriteLine("\n*************ClassProxyWithTarget*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var animal = generator.CreateClassProxyWithTarget
     
      (new Dog(), new AnimalInterceptor()); 5                 animal.Play(); 6  7                 Console.WriteLine(animal.GetType()); 8                 Console.WriteLine(animal.GetType().BaseType); 9 10                 var compositeField = animal.GetType().GetField("__target");11                 Console.WriteLine(compositeField);12 13                 foreach (var interfaceType in animal.GetType().GetInterfaces())14                 {15                     Console.WriteLine(interfaceType);16                 }17             }

运行结果

动态代理类图

等待上传中。

第三种：InterfaceProxyWithoutTarget

代码示例

1             { 2                 Console.WriteLine("\n*************InterfaceProxyWithoutTarget*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var animal = generator.CreateInterfaceProxyWithoutTarget
     
      (new AnimalInterceptor()); 5                 animal.Play(); 6  7                 Console.WriteLine(animal.GetType()); 8                 Console.WriteLine(animal.GetType().BaseType); 9 10                 var compositeField = animal.GetType().GetField("__target");11                 Console.WriteLine(compositeField);12 13                 foreach (var interfaceType in animal.GetType().GetInterfaces())14                 {15                     Console.WriteLine(interfaceType);16                 }17             }

运行结果

动态代理类图

等待上传中。

第四种：InterfaceProxyWithTarget

测试代码

1             { 2                 Console.WriteLine("\n*************InterfaceProxyWithTarget*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var animal = generator.CreateInterfaceProxyWithTarget
     
      (new Dog(), new AnimalInterceptor()); 5                 animal.Play(); 6  7                 Console.WriteLine(animal.GetType()); 8                 Console.WriteLine(animal.GetType().BaseType); 9 10                 var compositeField = animal.GetType().GetField("__target");11                 Console.WriteLine(compositeField);12 13                 foreach (var interfaceType in animal.GetType().GetInterfaces())14                 {15                     Console.WriteLine(interfaceType);16                 }17             }

运行结果

动态代理类图

等待上传中。

第五种：InterfaceProxyWithTargetInterface

测试代码

1             { 2                 Console.WriteLine("\n*************InterfaceProxyWithTargetInterface*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var animal = generator.CreateInterfaceProxyWithTargetInterface
     
      (new Dog(), new AnimalInterceptor()); 5                 animal.Play(); 6  7                 Console.WriteLine(animal.GetType()); 8                 Console.WriteLine(animal.GetType().BaseType); 9 10                 var compositeField = animal.GetType().GetField("__target");11                 Console.WriteLine(compositeField);12 13                 foreach (var interfaceType in animal.GetType().GetInterfaces())14                 {15                     Console.WriteLine(interfaceType);16                 }17             }

运行结果

动态代理类图

等待上传中。

1种Mixin模式

测试代码

1             { 2                 Console.WriteLine("\n*************Mixin*************\n"); 3                 var generator = new ProxyGenerator(); 4                 var options = new ProxyGenerationOptions(); 5                 options.AddMixinInstance(new RunAbility()); 6                 var animal = generator.CreateClassProxy
     
      (options, new AnimalInterceptor()); 7                 animal.Play(); 8                 (animal as IRunable).Run(); 9 10                 Console.WriteLine(animal.GetType());11                 Console.WriteLine(animal.GetType().BaseType);12 13                 var compositeField = animal.GetType().GetField("__target");14                 Console.WriteLine(compositeField);15 16                 foreach (var field in animal.GetType().GetFields())17                 {18                     if (field.Name.StartsWith("__mixin"))19                     {20                         Console.WriteLine(field);21                     }22                 }23 24                 foreach (var interfaceType in animal.GetType().GetInterfaces())25                 {26                     Console.WriteLine(interfaceType);27                 }28             }

运行结果