职责链模式(Chain of Responsibility Pattern):避免请求发送者与接收者耦合在一起,让多个对象都有可能接收请求,将这些对象连接成一条链,并且沿着这条链传递请求,直到有对象处理它为止。
模式角色与结构:
示例代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text; namespace CSharp.DesignPattern.ResponsibilityChainPattern
{
class Program
{
static void Main(string[] args)
{
// 需要注意,职责链模式并不创建职责链,职责链的创建工作必须由系统的其他部分来完成,
// 一般是在使用该职责链的客户端中创建职责链。
Handler annal = new Director();
Handler tony = new VicePresident();
Handler marc = new President();
Handler meeting = new Congress(); annal.SetSuccessor(tony);
tony.SetSuccessor(marc);
marc.SetSuccessor(meeting); Console.WriteLine("Request: President");
annal.HandleRequest("President"); Console.ReadLine();
}
} // 抽象处理类
abstract class Handler
{
protected Handler successor; // 维持对下家的引用 public void SetSuccessor(Handler successor)
{
this.successor = successor;
} public abstract void HandleRequest(String request);
} // 具体处理类
class Director : Handler
{
public override void HandleRequest(string request)
{
if (request == "Director")
{
Console.WriteLine("Director Handle...");
}
else
{
this.successor.HandleRequest(request); // 体现职责链
}
}
} // 具体处理类
class VicePresident : Handler
{
public override void HandleRequest(string request)
{
if (request == "VicePresident")
{
Console.WriteLine("VicePresident Handle...");
}
else
{
this.successor.HandleRequest(request); // 体现职责链
}
}
} // 具体处理类
class President : Handler
{
public override void HandleRequest(string request)
{
if (request == "President")
{
Console.WriteLine("President Handle...");
}
else
{
this.successor.HandleRequest(request); // 体现职责链
}
}
} // 具体处理类
class Congress : Handler
{
public override void HandleRequest(string request)
{
if (request == "Congress")
{
Console.WriteLine("Congress Handle...");
}
else
{
this.successor.HandleRequest(request); // 体现职责链
}
}
}
}