策略模式的实现

    class Program
    ...{
        static void Main(string[] args)
        ...{
            Duck duck = new MiniDuck();
            duck.fly();
            FlyBehavior Fly = new FlyRocketPowered();
            duck.SetFlyBehavior=Fly;
            duck.fly();
        }
    }


    public abstract   class Duck 
    ...{
        public FlyBehavior flyBehavior;
        public void fly()
        ...{
            flyBehavior.fly();
        }
        public FlyBehavior SetFlyBehavior
        ...{
            set 
            ...{
                this.flyBehavior = value;
            }
        }
    }

    public class MiniDuck:Duck
    ...{
        public MiniDuck()        
        ...{
            this.flyBehavior = new FlyWithWing();
        }
    }

    /**//// <summary>
    /// 飞行的接口申明
    /// </summary>
    public interface  FlyBehavior 
    ...{
         void fly();
    }

    /**//// <summary>
    /// 实现飞行的接口
    /// </summary>
    public class FlyWithWing : FlyBehavior 
    ...{
        public void fly() 
        ...{
            Console.Write("我是能飞的");
        }
    }

    public class FlyRocketPowered : FlyBehavior 
    ...{
        public void fly() 
        ...{
            Console.Write("有火箭带也能飞");
        }
    }