浅尝DesignPattern_ChainOfResponsibility

UML:

通过让多个对象都有机会处理该请求,来避免耦合请求的发送者的接收器，。链接接收对象并且通过链来传递请求直到一个对象处理它。

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it. 

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it. 

 

• Handler   ()
  • defines an interface for handling the requests
  • 定义一个处理请求的接口
  • (optional) implements the successor link
  • 实现successor链接
• ConcreteHandler   ()
  • handles requests it is responsible for
  • 处理负责的请求
  • can access its successor
  • 能够访问successor 
  • if the ConcreteHandler can handle the request, it does so; otherwise it forwards the request to its successor
  • 如果ConcreteHandler能处理请求,它也可以.
• Client   ()
  • initiates the request to a ConcreteHandler object on the chain  
  • 启动链上的请求

 

Sample:

 

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} handled request {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} handled request {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} handled request {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}

 

#region ChainOR
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);
}
#endregion

 

 

 

 

 

 

 

 

 

 

 

转载于:https://www.cnblogs.com/TivonStone/archive/2010/04/30/1724741.html