设计模式之C++版

这里，对设计模式的概念就不细说了，凡是用过或者看过这方面书籍的都应该有所了解。

鄙人认为正是设计模式的出现，使得C++的三大性质——封装、继承和多态发挥的淋漓尽致。

尤其是多态性质，可以说是面向对的精髓所在。

封装性是为了很好的管理数据和方法；继承是为了提高代码的重用；而多态的出现，使得执行过程中，出现多样性，调用一个方法时，可以从父类跳到子类执行，又从子类调用父类的方法等等，函数调用过程呈现曲线形式。

总之，执行期，表现出多样化。

所以，要想很好的掌握设计模式，必须对多态性有很深的了解，再则，对类与类之间的关系有个清晰的认识，类与类之间的关系，无非6大关系——继承和实现、依赖和关联、组合和聚合。

每个模式都是对类之间的这6种关系进行组合，呈现出不同的表现形式，下面，一一介绍23种设计模式，用到的类之间的关系和C++代码（在VS2008调试没问题的）。

先说创建型模式：1、Factory Pattern 工厂模式使用到的类关系：继承和依赖图 1 工厂模式UML图Head.h#ifndef_FACTORY_HEAD_#define_FACTORY_HEAD_#include<iostream>using std::cout;using std::endl;class CProduct;class CFactory{private:public:CFactory(){}~CFactory(){}public:virtual CProduct* CreateProduct() = 0; };class CConcreteFactory : public CFactory {private:public:CConcreteFactory();~CConcreteFactory();public:virtual CProduct* CreateProduct(); };class CProduct{private:public:CProduct(){}~CProduct(){}public:virtual void Operation()=0;};class CConcreteProduct1 : public CProduct {private:public:CConcreteProduct1();~CConcreteProduct1();public:virtual void Operation();};class CConcreteProduct2 : public CProduct {private:public:CConcreteProduct2();~CConcreteProduct2();public:virtual void Operation();};#endifMain.cpp#include"Head.h"CConcreteFactory::CConcreteFactory(){}CConcreteFactory::~CConcreteFactory(){}CProduct* CConcreteFactory::CreateProduct(){return new CConcreteProduct2();}////////////////////////////////////////////////////////// CConcreteProduct1::CConcreteProduct1(){}CConcreteProduct1::~CConcreteProduct1(){}void CConcreteProduct1::Operation(){cout<<"CConcreteProduct1 Operation!"<<endl; }////////////////////////////////////////////////////// CConcreteProduct2::CConcreteProduct2(){}CConcreteProduct2::~CConcreteProduct2(){}void CConcreteProduct2::Operation(){cout<<"CConcreteProduct2 Operation!"<<endl; }int main(){CFactory* pFac = new CConcreteFactory();CProduct* pPro = pFac->CreateProduct();if (pPro != NULL)pPro->Operation();delete pPro;delete pFac;return 0;}2、AbstractFactory Pattern 抽象工厂模式使用到的类关系：继承和依赖图2 抽象工厂模式Head.h#ifndef_ABSTRACT_FACTORY_HEAD_#define_ABSTRACT_FACTORY_HEAD_#include<iostream>using std::cout;using std::endl;class CProductA;class CProductB;class CAbstractFactory{private:public:CAbstractFactory(){}~CAbstractFactory(){}public:virtual CProductA* CreateProductA() = 0;virtual CProductB* CreateProductB() = 0;};class CConcreteAbstractFactory1 : public CAbstractFactory {private:public:CConcreteAbstractFactory1();~CConcreteAbstractFactory1();public:virtual CProductA* CreateProductA();virtual CProductB* CreateProductB();};class CConcreteAbstractFactory2 : public CAbstractFactory {private:public:CConcreteAbstractFactory2();~CConcreteAbstractFactory2();public:virtual CProductA* CreateProductA();virtual CProductB* CreateProductB();};class CProductA{private:public:CProductA(){}~CProductA(){}public:virtual void Operation()=0;};class CConcreteProductA1 : public CProductA{private:public:CConcreteProductA1();~CConcreteProductA1();public:virtual void Operation();};class CConcreteProductA2 : public CProductA{private:public:CConcreteProductA2();~CConcreteProductA2();public:virtual void Operation();class CProductB{private:public:CProductB(){}~CProductB(){}public:virtual void Operation()=0;};class CConcreteProductB1 : public CProductB{private:public:CConcreteProductB1();~CConcreteProductB1();public:virtual void Operation();};class CConcreteProductB2 : public CProductB{private:public:CConcreteProductB2();~CConcreteProductB2();public:virtual void Operation();};#endifMain.cpp#include"Head.h"CConcreteAbstractFactory1::CConcreteAbstractFactory1() {}CConcreteAbstractFactory1::~CConcreteAbstractFactory1() {}CProductA* CConcreteAbstractFactory1::CreateProductA() {return new CConcreteProductA1();}CProductB* CConcreteAbstractFactory1::CreateProductB() {return new CConcreteProductB1();}CConcreteAbstractFactory2::CConcreteAbstractFactory2(){}CConcreteAbstractFactory2::~CConcreteAbstractFactory2(){}CProductA* CConcreteAbstractFactory2::CreateProductA(){return new CConcreteProductA2();}CProductB* CConcreteAbstractFactory2::CreateProductB(){return new CConcreteProductB2();}//////////////////////CConcreteProductA1/////////////////////////////////// CConcreteProductA1::CConcreteProductA1(){}CConcreteProductA1::~CConcreteProductA1(){}void CConcreteProductA1::Operation(){cout<<"CConcreteProductA1 Operation!"<<endl;}//////////////////////CConcreteProductA2/////////////////////////////////// CConcreteProductA2::CConcreteProductA2(){}CConcreteProductA2::~CConcreteProductA2(){}void CConcreteProductA2::Operation(){cout<<"CConcreteProductA2 Operation!"<<endl;}//////////////////////CConcreteProductB1/////////////////////////////////// CConcreteProductB1::CConcreteProductB1(){}CConcreteProductB1::~CConcreteProductB1(){}void CConcreteProductB1::Operation(){cout<<"CConcreteProductB1 Operation!"<<endl;}//////////////////////CConcreteProductB2/////////////////////////////////// CConcreteProductB2::CConcreteProductB2(){}CConcreteProductB2::~CConcreteProductB2(){}void CConcreteProductB2::Operation(){cout<<"CConcreteProductB2 Operation!"<<endl;}int main(){CAbstractFactory* pFac = new CConcreteAbstractFactory1();CProductA* pProA1 = pFac->CreateProductA();if (pProA1 != NULL)pProA1->Operation();CProductB* pProB1 = pFac->CreateProductB();if (pProB1 != NULL)pProB1->Operation();delete pProA1;delete pProB1;delete pFac;return 0;}3、单例模式使用到的类关系：无单例模式很简单，目的就是只创建一个实例，关键是他的构造函数私有的，所以在外部是不能被调用的，只能使用自己的实例化函数进行构造，而实例化函数中，保证了只创建一个实例，下次在调用，如果判断已经创建了一个实例，则只返回已创建的实例，详看程序。