行为型对象模式——责任链模式

责任链模式是一种行为型设计模式，其核心思想是将请求的发送者与接收者解耦，通过将多个处理者对象串联成一条链，请求沿着链传递，直到被某个处理者处理为止。

适用于

①有多个的对象可以处理一个请求，哪个对象处理请求运行时刻自动确认。

②想在不明确指定接收者的情况下向多个对象中的一个提交一个请求。

③可处理一个请求的对象集合应被动态指定

类图如下

    internal class Program
    {
        static void Main(string[] args)
        {
            //创建请假对象
            LeaveRequest leave = new LeaveRequest("小米", 6, "外出");

            //创建领导对象
            GroupHandler group = new GroupHandler();
            ManagerHandler manager = new ManagerHandler();
            GeneralHandler general = new GeneralHandler();

            //设置责任链
            group.SetHandler(manager);
            manager.SetHandler(general);

            //小米提交请假
            group.Submit(leave);


        }
    }

    /// <summary>
    /// 请假条类
    /// 在责任链中进行流转
    /// </summary>
    internal class LeaveRequest
    {
        public string Name { get; }

        public int Num { get; }

        public string Content { get; }

        public LeaveRequest(string name, int num, string content)
        {
            Name = name;
            Num = num;
            Content = content;
        }
    }

    /// <summary>
    /// 抽象处理者类
    /// </summary>
    internal abstract class Handler
    {
        protected readonly static int NUM_ONE = 1;
        protected readonly static int NUM_THREE = 3;
        protected readonly static int NUM_SEVEN = 7;

        private int numStart;
        private int numEnd;

        //上级处理者
        private Handler handler;

        public Handler(int numStart)
        {
            this.numStart = numStart;
        }

        public Handler(int numStart, int numEnd)
        {
            this.numStart = numStart;
            this.numEnd = numEnd;
        }

        //设置上级领导对象
        public void SetHandler(Handler handler)
        {
            this.handler = handler;
        }

        //处理请假条方法
        public abstract void HangdleLeave(LeaveRequest request);

        public void Submit(LeaveRequest request)
        {
            this.HangdleLeave(request);
            if(this.handler != null && request.Num > numEnd)
            {
                this.handler.Submit(request);
            }
            else
            {
                Console.WriteLine("流程结束！");
            }
        }
    }

    internal class GroupHandler : Handler
    {
        public GroupHandler() : base(0, NUM_ONE)
        {
        }

        public override void HangdleLeave(LeaveRequest request)
        {
            Console.WriteLine(request.Name + "请假" + request.Name + "天，" + request.Content + "。");
            Console.WriteLine("小组长审核：同意");
        }
    }

    internal class ManagerHandler : Handler
    {
        public ManagerHandler() : base(NUM_ONE, NUM_THREE)
        {
        }

        public override void HangdleLeave(LeaveRequest request)
        {
            Console.WriteLine(request.Name + "请假" + request.Name + "天，" + request.Content + "。");
            Console.WriteLine("部门经理审核：同意");
        }
    }

    internal class GeneralHandler : Handler
    {
        public GeneralHandler() : base(NUM_THREE, NUM_SEVEN)
        {
        }

        public override void HangdleLeave(LeaveRequest request)
        {
            Console.WriteLine(request.Name + "请假" + request.Name + "天，" + request.Content + "。");
            Console.WriteLine("总经理审核：同意");
        }
    }