状态模式：当一个对象的内在状态改变时运行改变其行为，这个对象看起来像是改变了其类。

状态模式结构

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本例中状态只有两个，不能概括那种状态转换过于复杂的情况，但本例主要是用来表示状态模式的。
namespace 电灯的状态
{
 
    //抽象状态类
    abstract class LightState
    {
        public abstract void PressSwitch(Light light);  //按下按钮
    }

    //电灯打开状态类
    class LightOn : LightState
    {
        public override void PressSwitch(Light light)
        {
            
            light.State  = new LightOff();
            Console.WriteLine("电灯已关");
            
        }
    }

    //电灯关闭状态类
    class LightOff : LightState
    {
        public override void PressSwitch(Light light)
        {
            
            light.State = new LightOn();
            Console.WriteLine("电灯已开");

        }
    }

    //电灯类
    class Light
    {
        private LightState state;

        public LightState State
        {
            get { return state; }
            set { state = value; }
        }

        public Light(LightState state) //构造时设置初始状态
        {
            this.state = state;
        }

        public void PressLightSwitch()
        {
            state.PressSwitch(this);  //转换本类的状态
        }
    }




    class Program
    {
        static void Main(string[] args)
        {
            Light light = new Light(new LightOn());  //打开状态

            //反复开关。。。
            light.PressLightSwitch();
            light.PressLightSwitch();
            light.PressLightSwitch();
            light.PressLightSwitch();
            light.PressLightSwitch();


        }
    }

状态模式（Statue）

状态模式结构