职责链模式(Chain of Responsibility)

重要概念

1. 使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

2.请求是沿着链条传递到有一个处理点对象负责处理这个请求为止。请求者无需关心谁会处理这个请求。

3. 接收者和发送者都没有对方的明确信息，且链中的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，他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的候选接收者的引用。

4. 从执行流程上感觉和 case break 相似。

5. 随时地增加或修改该处理一个请求的结构（处理顺序，处理点数量），增强了给对象指派职责的灵活性。

6. 解决大量分支判断造成的难维护，灵活性差的问题。

 

 

 

 

 

示例程序

using System;
using System.Collections.Generic;
using System.Text;namespace 职责链模式
{class Program{static void Main(string[] args){//初始化三个职责链处理点Handler h1 = new ConcreteHandler1();Handler h2 = new ConcreteHandler2();Handler h3 = new ConcreteHandler3();//设置职责链的连接处理顺序h1.SetSuccessor(h2);h2.SetSuccessor(h3);int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 };foreach (int request in requests){//要从职责链的最小端，也就是开始的那头发出请求。h1.HandleRequest(request);}Console.Read();}}abstract class Handler{protected Handler successor;public void SetSuccessor(Handler successor){this.successor = successor;}public abstract void HandleRequest(int request);}class ConcreteHandler1 : Handler{public override void HandleRequest(int request){if (request >= 0 && request < 10){Console.WriteLine("{0}  处理请求  {1}",this.GetType().Name, request);}else if (successor != null){successor.HandleRequest(request);}}}class ConcreteHandler2 : Handler{public override void HandleRequest(int request){if (request >= 10 && request < 20){Console.WriteLine("{0}  处理请求  {1}",this.GetType().Name, request);}else if (successor != null){successor.HandleRequest(request);}}}class ConcreteHandler3 : Handler{public override void HandleRequest(int request){if (request >= 20 && request < 30){Console.WriteLine("{0}  处理请求  {1}",this.GetType().Name, request);}else if (successor != null){successor.HandleRequest(request);}}}}

 

加薪代码2

 

using System;
using System.Collections.Generic;
using System.Text;namespace 职责链模式
{class Program{static void Main(string[] args){CommonManager jinli = new CommonManager("金利");Majordomo zongjian = new Majordomo("宗剑");GeneralManager zhongjingli = new GeneralManager("钟精励");jinli.SetSuperior(zongjian);zongjian.SetSuperior(zhongjingli);Request request = new Request();request.RequestType = "请假";request.RequestContent = "小菜请假";request.Number = 1;jinli.RequestApplications(request);Request request2 = new Request();request2.RequestType = "请假";request2.RequestContent = "小菜请假";request2.Number = 4;jinli.RequestApplications(request2);Request request3 = new Request();request3.RequestType = "加薪";request3.RequestContent = "小菜请求加薪";request3.Number = 500;jinli.RequestApplications(request3);Request request4 = new Request();request4.RequestType = "加薪";request4.RequestContent = "小菜请求加薪";request4.Number = 1000;jinli.RequestApplications(request4);Console.Read();}}//管理者abstract class Manager{protected string name;//管理者的上级protected Manager superior;public Manager(string name){this.name = name;}//设置管理者的上级public void SetSuperior(Manager superior){this.superior = superior;}//申请请求abstract public void RequestApplications(Request request);}//经理class CommonManager : Manager{public CommonManager(string name): base(name){ }public override void RequestApplications(Request request){if (request.RequestType == "请假" && request.Number <= 2){Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestContent, request.Number);}else{if (superior != null)superior.RequestApplications(request);}}}//总监class Majordomo : Manager{public Majordomo(string name): base(name){ }public override void RequestApplications(Request request){if (request.RequestType == "请假" && request.Number <= 5){Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestContent, request.Number);}else{if (superior != null)superior.RequestApplications(request);}}}//总经理class GeneralManager : Manager{public GeneralManager(string name): base(name){ }public override void RequestApplications(Request request){if (request.RequestType == "请假"){Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestContent, request.Number);}else if (request.RequestType == "加薪" && request.Number <= 500){Console.WriteLine("{0}:{1} 数量{2} 被批准", name, request.RequestContent, request.Number);}else if (request.RequestType == "加薪" && request.Number > 500){Console.WriteLine("{0}:{1} 数量{2} 再说吧", name, request.RequestContent, request.Number);}}}//申请class Request{//申请类别private string requestType;public string RequestType{get { return requestType; }set { requestType = value; }}//申请内容private string requestContent;public string RequestContent{get { return requestContent; }set { requestContent = value; }}//数量private int number;public int Number{get { return number; }set { number = value; }}}}