职责链模式
顾名思义，责任链模式（Chain of Responsibility Pattern）为请求创建了一个接收者对象的链。这种模式给予请求的类型，对请求的发送者和接收者进行解耦。这种类型的设计模式属于行为型模式。
在这种模式中，通常每个接收者都包含对另一个接收者的引用。如果一个对象不能处理该请求，那么它会把相同的请求传给下一个接收者，依此类推。
意图
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。
主要解决
职责链上的处理者负责处理请求，客户只需要将请求发送到职责链上即可，无须关心请求的处理细节和请求的传递，所以职责链将请求的发送者和请求的处理者解耦了。
何时使用
在处理消息的时候以过滤很多道。
如何解决
拦截的类都实现统一接口。
关键代码
Handler 里面聚合它自己，在 HanleRequest 里判断是否合适，如果没达到条件则向下传递，向谁传递之前 set 进去。
基本代码
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);
}
}
}示例
请假和调薪流程
步骤1 创建抽象处理类
//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);
}步骤2 实现抽象类的具体类
//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);
}
}
}步骤3 定义需处理的类
//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; }
}
}步骤4 使用命令模式
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();
}