动态代理的5模式使用示例和Mixin模式

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。

代码如下:
public interface IPlayable
    {
        void Play();
    }

    public class Animal : IPlayable
    {
        public virtual void Play()
        {
            Console.WriteLine("Animal.Play");
        }
    }

    public class Dog : Animal
    {
        public override void Play()
        {
            Console.WriteLine("Dog.Play");
        }
    }

    public interface IRunable
    {
        void Run();
    }

    public class RunAbility : IRunable
    {
        public void Run()
        {
            Console.WriteLine("RunAbility.Run");
        }
    }

    public class AnimalInterceptor : IInterceptor
    {
        public void Intercept(IInvocation invocation)
        {
            Console.WriteLine("Before AnimalInterceptor.Intercept");
            if (invocation.InvocationTarget != null)
            {
                invocation.Proceed();
            }
            Console.WriteLine("After AnimalInterceptor.Intercept");
        }
    }

第一种：ClassProxy

代码如下:
{
                Console.WriteLine("\n*************ClassProxy*************\n");
                var generator = new ProxyGenerator();
                var animal = generator.CreateClassProxy<Animal>(new AnimalInterceptor());
                animal.Play();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }

第二种：ClassProxyWithTarget

代码如下:
{
                Console.WriteLine("\n*************ClassProxyWithTarget*************\n");
                var generator = new ProxyGenerator();
                var animal = generator.CreateClassProxyWithTarget<Animal>(new Dog(), new AnimalInterceptor());
                animal.Play();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }

第三种：InterfaceProxyWithoutTarget

代码如下:
{
                Console.WriteLine("\n*************InterfaceProxyWithoutTarget*************\n");
                var generator = new ProxyGenerator();
                var animal = generator.CreateInterfaceProxyWithoutTarget<IPlayable>(new AnimalInterceptor());
                animal.Play();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }

第四种：InterfaceProxyWithTarget

代码如下:
{
                Console.WriteLine("\n*************InterfaceProxyWithTarget*************\n");
                var generator = new ProxyGenerator();
                var animal = generator.CreateInterfaceProxyWithTarget<IPlayable>(new Dog(), new AnimalInterceptor());
                animal.Play();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }

第五种：InterfaceProxyWithTargetInterface

代码如下:
{
                Console.WriteLine("\n*************InterfaceProxyWithTargetInterface*************\n");
                var generator = new ProxyGenerator();
                var animal = generator.CreateInterfaceProxyWithTargetInterface<IPlayable>(new Dog(), new AnimalInterceptor());
                animal.Play();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }

Mixin模式

代码如下:
{
                Console.WriteLine("\n*************Mixin*************\n");
                var generator = new ProxyGenerator();
                var options = new ProxyGenerationOptions();
                options.AddMixinInstance(new RunAbility());
                var animal = generator.CreateClassProxy<Animal>(options, new AnimalInterceptor());
                animal.Play();
                (animal as IRunable).Run();

                Console.WriteLine(animal.GetType());
                Console.WriteLine(animal.GetType().BaseType);

                var compositeField = animal.GetType().GetField("__target");
                Console.WriteLine(compositeField);

                foreach (var field in animal.GetType().GetFields())
                {
                    if (field.Name.StartsWith("__mixin"))
                    {
                        Console.WriteLine(field);
                    }
                }

                foreach (var interfaceType in animal.GetType().GetInterfaces())
                {
                    Console.WriteLine(interfaceType);
                }
            }