状态模式（State）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace State
{
    class Work
    {
        private State state;
        public Work()
        {
            this.state = new ForenoonState();
        }

        private double hour;
        public double Hour
        {
            get { return hour; }
            set { hour = value; }
        }

        public void SetState(State s)
        {
            this.state = s;
        }
        //为了调用state的行为
        public void WriteProgram()
        {
            state.WriteProgram(this);
        }
    }
    abstract class State
    {
        public abstract void WriteProgram(Work w);
    }
    class ForenoonState : State
    {
        public override void WriteProgram(Work w)
        {
            if (w.Hour < 12)
            {
                Console.WriteLine("当前时间上午{0}点,精神百倍！",w.Hour);
            }
            else
            {
                w.SetState(new NoonState());
                w.WriteProgram();
            }
        }
    }
    class NoonState : State
    {
        public override void WriteProgram(Work w)
        {
            if (w.Hour < 14)
            {
                Console.WriteLine("当前时间中午午{0}点,想睡觉！",w.Hour);
            }
            else
            {
                w.SetState(new AfternoonState());
                w.WriteProgram();
            }
        }
    }
    class AfternoonState : State
    {
        public override void WriteProgram(Work w)
        {
            if (w.Hour < 18)
            {
                Console.WriteLine("当前时间中午午{0}点,快下班了！", w.Hour);
            }
            else
            {
                w.SetState(new SleepingState());
                w.WriteProgram();
            }
        }
    }
    class SleepingState : State
    {
        public override void WriteProgram(Work w)
        {
            Console.WriteLine("当前时间中午午{0}点,睡着了！", w.Hour);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Work w = new Work();
            w.Hour = 9;
            w.WriteProgram();
            w.Hour = 13;
            w.WriteProgram();
            w.Hour = 17;
            w.WriteProgram();
            w.Hour = 23;
            w.WriteProgram();
        }
    }
}