《大话设计模式》学习笔记20：职责链模式

　　

　　

申请审批示例：

　　

1.请求类：

    public class Request
    {
        public string RequestType { get; set; }
        public string RequestContent { get; set; }
        public int Number { get; set; }
    }

2.Handler：

    public abstract class Manager
    {
        protected string name;
        protected Manager superiorManager;

        public Manager(string name)
        {
            this.name = name;
        }
        public void SetSuperior(Manager superiorManager)
        {
            this.superiorManager = superiorManager;
        }
        public abstract void RequestApplication(Request request);
    }

3.ConcreteHandler：

    public class CommonManager:Manager
    {
        public CommonManager(string name)
            :base(name)
        {

        }
        public override void RequestApplication(Request request)
        {
            if(request.RequestType=="请假"&&request.Number<=2)
            {
                Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestType, request.Number);
            }
            else
            {
                if(superiorManager!=null)
                {
                    superiorManager.RequestApplication(request);
                }
            }
        }
    }

    public class Majordomo:Manager
    {
        public Majordomo(string name)
            :base(name)
        {

        }
        public override void RequestApplication(Request request)
        {
            if(request.RequestType=="请假"&&request.Number<=5)
            {
                Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestType, request.Number);
            }
            else
            {
                if(superiorManager!=null)
                {
                    superiorManager.RequestApplication(request);
                }
            }
        }
    }

    public class GeneralManager:Manager
    {
        public GeneralManager(string name)
            :base(name)
        {

        }
        public override void RequestApplication(Request request)
        {
            if(request.RequestType=="请假")
            {
                Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestType, request.Number);
            }
            else if(request.RequestType=="加薪")
            {
                if (request.Number <= 500)
                {
                    Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestType, request.Number);
                }
                else
                {
                    Console.WriteLine("{0}:{1} 数量{2} 再说吧", name, request.RequestType, request.Number);
                }
            }
        }
    }

客户端代码：

    class Program
    {
        static void Main(string[] args)
        {
            Manager commonManager = new CommonManager("经理");
            Manager majordom = new Majordomo("总监");
            Manager generalManager = new GeneralManager("总经理");

            commonManager.SetSuperior(majordom);
            majordom.SetSuperior(generalManager);

            Request request = new Request();

            request.RequestType = "请假"; request.RequestContent = "事假"; request.Number = 1;
            commonManager.RequestApplication(request);

            request.RequestType = "请假"; request.RequestContent = "年假"; request.Number = 4;
            commonManager.RequestApplication(request);

            request.RequestType = "加薪"; request.RequestContent = "加薪一千"; request.Number = 1000;
            commonManager.RequestApplication(request);
        }
    }

　　优点：接收者和发送者都没有对方的明确信息，且链中对象自己也并不知道链的结构。结果是职责链可简化对象的相互连接，它们仅需保持一个指向其后继者的引用，而不需要保持它所有候选接受者的引用。