《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。