责任链模式 与中间件

1。 先看责任链模式：请假流程，抽象的经理和具体的级别不同的经理（只贴出级别1的经理）。

    public abstract class Manager
    {
        public string Name { get; set; }
        public Manager Leader { get; set; }
        public abstract void Approve(Request request);
    }

public class ManagerLevel1: Manager
    {
        public int Day { get; set; } = 3;
        public override void Approve(Request request)
        {
            if (request.Day <= Day)
            {
                Console.WriteLine($"一级管理者 {Name} 批准了 {request.Name},{request.Day}天");
            }
            else
            {
                Console.WriteLine($"{Name} 交给leader, {request.Day}天");
                Leader.Approve(request);
            }
        }
    }

    public class Request
    {
        public int Day { get; set; }
        public string Name { get; set; }
    }

主代码：

 Console.WriteLine("Hello World!");

            var app = new App();

            var m1 = new ManagerLevel1();
            var m2 = new ManagerLevel2();
            var m3 = new ManagerLevel3();

            m1.Leader = m2;
            m2.Leader = m3;

            var re = new Request() { Name = "张三", Day = 6};
            m1.Approve(re);

责任链模式结束，增加管理者：

    public  class App
    {
        List<Manager> managers { get; set; } = new List<Manager>();

        public App Use(Manager m)
        {
            var last= managers.LastOrDefault();
            if (last != null)
                last.Leader = m;

            managers.Add(m);

            return this;
        }
    }

主代码变成这样：

Console.WriteLine("Hello World!");

var app = new App();

var m1 = new ManagerLevel1();
var m2 = new ManagerLevel2();
var m3 = new ManagerLevel3();

app.Use(m1);
app.Use(m2);
app.Use(m3);

var re = new Request() { Name = "张三", Day = 6};
m1.Approve(re);