职责链模式（Chain of Responsibility）

//注意职责链模式和状态模式的区别。

状态模式的逻辑顺序不一定是线性的。（每个状态中只需判断即可）

职责链模式的逻辑顺序是线性的。（每个Handler要设置Prior）

/*
 * 高校学生请假需要符合学校规定，假如班主任可以批准1天假，系主任可以批
 * 准7天假，各学院院长可以批准30天，学校校长可以批准1年。应用职责链模
 * 式，用C#控制台应用程序实现该设计。
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ChainOfResponsibility
{
    abstract class Teacher
    {
        protected string name;
        protected Teacher prior;
        public Teacher(string name)
        {
            this.name = name;
        }
        public void SetPrior(Teacher prior)
        {
            this.prior = prior;
        }
        public abstract void Handle(int request);
    }
    class BanZhuRen : Teacher
    {
        public BanZhuRen(string name)
            : base(name)
        { }
        public override void Handle(int request)
        {
            if (request == 1)
            {
                Console.WriteLine("{0}:学生请假" + request + "天被批准了！", name);
            }
            else
            {
                prior.Handle(request);
            }
        }
    }
    class XiZhuRen : Teacher
    {
        public XiZhuRen(string name)
            : base(name)
        { }
        public override void Handle(int request)
        {
            if (request <= 7)
            {
                Console.WriteLine("{0}:学生请假" + request + "天被批准了！", name);
            }
            else
            {
                prior.Handle(request);
            }
        }
    }
    class YuanZhang : Teacher
    {
        public YuanZhang(string name)
            : base(name)
        { }
        public override void Handle(int request)
        {
            if (request <= 30)
            {
                Console.WriteLine("{0}:学生请假" + request + "天被批准了！", name);
            }
            else
            {
                prior.Handle(request);
            }
        }
    }
    class XiaoZhang : Teacher
    {
        public XiaoZhang(string name)
            : base(name)
        { }
        public override void Handle(int request)
        {
            if (request <= 365)
            {
                Console.WriteLine("{0}:学生请假" + request + "天被批准了！", name);
            }
            else
            {
                Console.WriteLine("{0}:请假这么多天，干脆休学一年算了！", name);
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            BanZhuRen bzr = new BanZhuRen("班竹韧");
            XiZhuRen xzr = new XiZhuRen("西祝任");
            YuanZhang yz = new YuanZhang("袁章");
            XiaoZhang xz = new XiaoZhang("肖长");

            bzr.SetPrior(xzr);
            xzr.SetPrior(yz);
            yz.SetPrior(xz);

            string off_days;
            for (int i = 0; i < 5; i++)
            {
                Console.WriteLine("输入请假天数：");
                off_days = Console.ReadLine();
                bzr.Handle(Convert.ToInt16(off_days));
            }
        }
    }
}