C++ 设计模式（六）brigde模式

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作用：将抽象部分与它的实现部分分离，使得它们可以独立地变化.

UML结构图:

9. C++实现Structural - Bridge模式 - 玄机逸士 - 玄机逸士博客

Bridge的实现方式其实和Builde十分的相近,可以这么说:本质上是一样的,只是封装的东西不一样罢了.两者的实现都有如下的共同点:抽象出来一个基类,这个基类里面定义了共有的一些行为,形成接口函数(对接口编程而不是对实现编程),这个接口函数在Buildier中是BuildePart函数在Bridge中是OperationImpl函数;其次,聚合一个基类的指针,如Builder模式中Director类聚合了一个Builder基类的指针,而Brige模式中Abstraction类聚合了一个Implementor基类的指针(优先采用聚合而不是继承);而在使用的时候,都把对这个类的使用封装在一个函数中,在Bridge中是封装在Director::Construct函数中,因为装配不同部分的过程是一致的,而在Bridge模式中则是封装在Abstraction::Operation函数中,在这个函数中调用对应的Implementor::OperationImpl函数.就两个模式而言,Builder封装了不同的生成组成部分的方式,而Bridge封装了不同的实现方式.

abstraction.h

#ifndef ABSTRACTION_H_#define ABSTRACTION_H_#include "AbstractionImp.h"class AbstractionImp;class Abstraction{public:virtual ~Abstraction();virtual void Operation()=0;protected:Abstraction();private:};class RefinedAbstration:public Abstraction{public:RefinedAbstration(AbstractionImp* imp);virtual ~RefinedAbstration(); virtual void Operation();protected:private:AbstractionImp* m_imp;};#endif

abstraction.cpp

#include "abstraction.h"#include<iostream>Abstraction::Abstraction(){using std::cout;using std::endl;cout<<"construction Abstraction"<<endl;}Abstraction::~Abstraction(){using std::cout;using std::endl; cout<<"deconstruction Abstraction"<<endl;}RefinedAbstration::RefinedAbstration(AbstractionImp* imp){this->m_imp=imp;}RefinedAbstration::~RefinedAbstration(){using std::cout;using std::endl;//delete m_imp;cout<<"deconstruction RefinedAbstraction"<<endl;}void RefinedAbstration::Operation(){m_imp->Operation();}

abstractionImp.h

#ifndef ABSTRACTIONIMP_H_#define ABSTRACTIONIMP_H_class AbstractionImp{protected:AbstractionImp();public:virtual ~AbstractionImp();virtual void Operation()=0;private:};class ConcreteAbstractionImp1:public AbstractionImp{public: ConcreteAbstractionImp1();virtual ~ConcreteAbstractionImp1();virtual void Operation();};class ConcreteAbstractionImp2:public AbstractionImp{public:ConcreteAbstractionImp2();virtual ~ConcreteAbstractionImp2();virtual void Operation();};#endif

abstractionImp.cpp

#include "AbstractionImp.h"#include <iostream>AbstractionImp::AbstractionImp(){using std::cout;using std::endl;cout<<"construction AbstractionImp"<<endl;}AbstractionImp::~AbstractionImp(){using std::cout;using std::endl;cout<<"deconstruction AbstractionImp"<<endl;}ConcreteAbstractionImp2::ConcreteAbstractionImp2(){using std::cout;using std::endl;cout<<"construction ConcreteAbstractionImp2"<<endl;}ConcreteAbstractionImp2::~ConcreteAbstractionImp2(){using std::cout;using std::endl;cout<<"deconstruction ConcreteAbstractionImp2"<<endl;}void ConcreteAbstractionImp2::Operation(){using std::cout;using std::endl;cout<<"concreteAbstractionImp2 operation"<<endl;}ConcreteAbstractionImp1::ConcreteAbstractionImp1(){using std::cout;using std::endl;cout<<"construction concreteAbstractionImp1"<<endl;}ConcreteAbstractionImp1::~ConcreteAbstractionImp1(){using std::cout;using std::endl;cout<<"deconstruction concreateAbstractionImp1"<<endl;}void ConcreteAbstractionImp1::Operation(){using std::cout;using std::endl;cout<<"ConcreteAbstractionImp1 operation"<<endl;}

main.cpp