拆分复杂的if-else判断分支  把这些逻辑放在类里面完成

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


namespace DesignPytternDemo
{
    public interface ITime
    {
        void SayHello();
    }


    public abstract class BaseTime : ITime
    {
        public int Time { get; set; }
        public abstract void SayHello();
        public BaseTime(int t)
        {
            this.Time = t;
        }


    }


    public class Morning : BaseTime
    {
        public Morning(int t) : base(t) { }


        public override void SayHello()
        {
            if (this.Time >= 7 && this.Time < 12)
            {
                Console.WriteLine("good morning,sir" + " time is {0}" , this.Time);
            }
            else
            {
                new Noon(this.Time).SayHello();
            }
        }
    }
    public class Noon : BaseTime
    {
        public Noon(int t) : base(t) { }


        public override void SayHello()
        {
            if (this.Time >= 12 && this.Time <= 13)
            {
                Console.WriteLine("have a nice lunch ,sir" + " time is {0}" , this.Time);
            }
            else
            {
                new AfterNoon(this.Time).SayHello();
            }
        }
    }


    public class AfterNoon : BaseTime
    {
        public AfterNoon(int t) : base(t) { }


        public override void SayHello()
        {
            if (this.Time > 13 && this.Time <= 18)
            {
                Console.WriteLine("good afternoon,sir" + " time is {0}" , this.Time);
            }
            else
            {
                new Night(this.Time).SayHello();
            }
        }
    }


    public class Night : BaseTime
    {
        public Night(int t) : base(t) { }


        public override void SayHello()
        {
            if (this.Time > 18 && this.Time <= 24)
            {
                Console.WriteLine("good evening,sir" + " time is {0}" ,this.Time);
            }
            else
            {
                new DeepNight(this.Time).SayHello();
            }
        }
    }


    public class DeepNight : BaseTime
    {
        public DeepNight(int t) : base(t) { }


        public override void SayHello()
        {
            if (this.Time >= 0 && this.Time < 7)
            {
                Console.WriteLine("have a good sleep,sir" + " time is {0}" ,this.Time);
            }
            else
            {
                Console.WriteLine("oh,unexpected time {0},", this.Time);
            }
        }
    }
}

 static void Main(string[] args)
        {
            BaseTime bt = new Morning(1);
            bt.SayHello();
            bt.Time = 8;
            bt.SayHello();
            bt.Time = 12;
            bt.SayHello();
            bt.Time = 14;
            bt.SayHello();
            bt.Time = 21;
            bt.SayHello();


            Console.ReadLine();
        }