public class MvcEngine
{public async Task StartAsync(Uri address){await ListenAsync(address);while (true){var request = await ReceiveAsync();var controller = await CreateControllerAsync(request);var view = await ExecuteControllerAsync(controller);await RenderViewAsync(view);}}protected virtual Task ListenAsync(Uri address);protected virtual Task<Request> ReceiveAsync();protected virtual Task<Controller> CreateControllerAsync(Request request);protected virtual Task<View> ExecuteControllerAsync(Controller controller);protected virtual Task RenderViewAsync(View view);
}

public class FoobarMvcEngine : MvcEngine
{protected override Task<View> CreateControllerAsync (Request request){<<省略实现>>}
}

public interface IWebLister
{Task ListenAsync(Uri address);Task<HttpContext> ReceiveAsync();
}public interface IControllerActivator
{Task<Controller> CreateControllerAsync(HttpContext httpContext);Task ReleaseAsync(Controller controller);
}public interface IControllerExecutor
{Task<View> ExecuteAsync(Controller controller, HttpContext httpContext);
}public interface IViewRender
{Task RendAsync(View view, HttpContext httpContext);
}

public class MvcEngine
{public async Task StartAsync(Uri address){var listener = GetWebLister();var activator = GetControllerActivator();var executor = GetControllerExecutor();var render = GetViewRender();await listener.ListenAsync(address);while (true){var httpContext = await listener.ReceiveAsync();var controller = await activator.CreateControllerAsync(httpContext);try{var view = await executor.ExecuteAsync(controller, httpContext);await render.RendAsync(view, httpContext);}finally{await activator.ReleaseAsync(controller);}}}protected virtual IWebLister GetWebLister(); protected virtual IControllerActivator GetControllerActivator();protected virtual IControllerExecutor GetControllerExecutor();protected virtual IViewRender GetViewRender();
}

public class SingletonControllerActivator : IControllerActivator
{         public Task<Controller> CreateControllerAsync(HttpContext httpContext){<<省略实现>>}public Task ReleaseAsync(Controller controller) => Task.CompletedTask;
}public class FoobarMvcEngine : MvcEngine
{protected override ControllerActivator GetControllerActivator() => new SingletonControllerActivator();
}

public interface IMvcEngineFactory
{IWebLister GetWebLister();IControllerActivator GetControllerActivator();IControllerExecutor GetControllerExecutor();IViewRender GetViewRender();
}public class MvcEngineFactory： IMvcEngineFactory
{IWebLister GetWebLister();IControllerActivator GetControllerActivator();IControllerExecutor GetControllerExecutor();IViewRender GetViewRender();
}

public class MvcEngine
{public IMvcEngineFactory EngineFactory { get; }public MvcEngine(IMvcEngineFactory engineFactory = null) => EngineFactory = engineFactory??new MvcEngineFactory();public async Task StartAsync(Uri address){var listener = EngineFactory.GetWebLister();var activator = EngineFactory.GetControllerActivator();var executor = EngineFactory.GetControllerExecutor();var render = EngineFactory.GetViewRender();await listener.ListenAsync(address);while (true){var httpContext = await listener.ReceiveAsync();var controller = await activator.CreateControllerAsync(httpContext);try{var view = await executor.ExecuteAsync(controller, httpContext);await render.RendAsync(view, httpContext);}finally{await activator.ReleaseAsync(controller);}}}}

public class FoobarEngineFactory : EngineFactory
{public override ControllerActivator GetControllerActivator(){return new SingletonControllerActivator();}
}public class App
{static void Main(string[] args){Uri address = new Uri("http://0.0.0.0:8080/mvcapp");MvcEngine engine     = new MvcEngine(new FoobarEngineFactory());engine.Start(address);}
}