C++设计模式之十三：Chain of Responsibility（职责链）

来源：互联网发布：大智慧贵金属分析软件编辑：程序博客网时间：2024/06/14 04:10

一、意图：

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。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

二、类图：

三、组成元素：

Handler：请求接口；
ConcreteHandler：具体处理请求的接口；

四、实现代码：

#include<iostream>using namespace std;class Handler{public:Handler(Handler* p = 0) : pHandler(p) { }virtual void setSuccessor( Handler* pH) { pHandler = pH; }virtual void handlerRequest(int request){ }protected:Handler* pHandler;};class ConcreteHandler1 : public Handler{public:ConcreteHandler1(Handler* p ) : Handler( p ) { }void handlerRequest( int request ){if (request >=0 && request<= 10){cout<<"request= "<<request<<" handler"<<endl;}else{pHandler->handlerRequest(request);}}};class ConcreteHandler2 : public Handler{public:ConcreteHandler2(Handler* p) : Handler( p ) { }void handlerRequest( int request ){if (request >=10 && request<= 20){cout<<"request= "<<request<<" handler"<<endl;}else{pHandler->handlerRequest(request);}}};class ConcreteHandler3 : public Handler{public:ConcreteHandler3(Handler* p) : Handler( p ) { }void handlerRequest( int request ){if (request >=20 && request<= 30){cout<<"request= "<<request<<" handler"<<endl;}else{cout<<"本类一定要处理一切情况"<<endl;//pHandler->handlerRequest(request);}}};void main(){Handler* p1 = new ConcreteHandler1(0);//p1->handlerRequest(3); 测试Handler* p2 = new ConcreteHandler2(0);Handler* p3 = new ConcreteHandler3(0);p1->setSuccessor(p2);p2->setSuccessor(p3);int a[] = {7,9,16,13,18,21,35 };for ( int i = 0 ; i<= 6 ; ++i ){p1->handlerRequest(a[i]);}}