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定义：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。
优点：当客户提交一个请求时，请求时沿链传递直至有一个ConcreteHandler对象负责处理它。这就使得接收者和发送者都没有对方的明白信息，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，它们仅需保持一个指向其后继者的引用，而不需保持它全部的候选接收者的引用。这就大大减少了耦合度了。因为式在client来定义链的结构，也就是说。我能够随时得添加或改动处理一个请求的结构。
增强了给对象指派职责的灵活性。
结构图：
基本代码：
using System;
using System.Collections.Generic;
using System.Text;
namespace 职责链模式
{
class Program
{
static void Main(string[] args)
{
Handler h1 = new ConcreteHandler1();
Handler h2 = new ConcreteHandler2();
Handler h3 = new ConcreteHandler3();
h1.SetSuccessor(h2);
h2.SetSuccessor(h3);
int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 };
foreach (int request in requests)
{
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);
}
}
}
}
样例：
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; }
}
}
}