外观模式

外观模式被用来把一组复杂的类包装在一个比较简单的封装接口中。

摘自：http://www.cnblogs.com/saville/archive/2012/10/18/2730089.html

以汽车为例。首先定义引擎、车轮、刹车等子系统。

   class Engine
    {
        public void Start()
        {
            Console.WriteLine("Engine Start");
        }
    }

    class Wheel
    {
        public void TurnOn()
        {
            Console.WriteLine("Wheel is turned");
        }
        public void Stop()
        {
            Console.WriteLine("Wheel is stopped");
        }
    }

    class Braker
    {
        public void Brake()
        {
            Console.WriteLine("Brake!");
        }
    }

接着定义汽车的Facade对象。

    class CarFacade
    {
        private Engine _engine;
        private Wheel[] _wheels;
        private Braker _braker;

        public CarFacade()
        {
            _engine = new Engine();
            _wheels = new Wheel[4];
            for (int i = 0; i < _wheels.Length; i++)
            {
                _wheels[i] = new Wheel();
            }
            _braker = new Braker();
        }
        public void Run()
        {
            _engine.Start();
            foreach (Wheel wheel in _wheels)
            {
                wheel.TurnOn();
            }
        }
        public void Brake()
        {
            _braker.Brake();
            foreach (Wheel wheel in _wheels)
            {
                wheel.Stop();
            }
        }
    }

只需要使用Façade对象即可实现对汽车的操作。

    static void Main(string[] args)
    {
        CarFacade car = new CarFacade();
        car.Run();
        car.Brake();
        Console.ReadLine();
    }