【嵌入式c++】设计模式之工厂模式简单工厂模式（simpleFactory）

题目描述:

Factory

动机(motivation)

实例化对象的时候不再使用 new Object()形式&＃xff0c;可以根据用户的选择条件来实例化相关的类。对于客户端来说&＃xff0c;去除了具体的类的依赖。只需要给出具体实例的描述给工厂&＃xff0c;工厂就会自动返回具体的实例对象。

模式定义

根据需求创建对象的种类。
——《设计模式》GoF

要点总结

有时会和其他模式解和使用&＃xff0c;我们无需提供具体的子类类名&＃xff0c;只需要提供一个字符串即可得到相应的实例对象。这样的话&＃xff0c;当子类的类名更换或者增加子类时我们都无需修改客户端代码&＃xff0c;只需要在简单工厂类上增加一个分支判断代码即可。

代码结构

.
├── build.sh
├── clearBuild.sh
├── CMakeLists.txt
├── src
│ ├── examStu.cpp
│ ├── include
│ │ └── examStu.h
│ └── main.cpp


源码例子

examStu.h

#ifndef _EXANSTU__
#define _EXANSTU__
#include
#include
#include
using namespace std;typedef enum _eShoesType{SHOES_TYPE_BASE &＃61; 0,SHOES_TYPE_NIKE &＃61; 1,SHOES_TYPE_ADIDAS &＃61; 2,SHOES_TYPE_HUILI &＃61; 3,SHOES_TYPE_ERROR &＃61; -1
}eShoesType;class ShoesBase
{
public:ShoesBase(){cout << "ShoesBase() called"<<endl;}virtual ~ShoesBase(){cout << "~ShoesBase() called"<<endl;}virtual void ShowTag()&＃61;0;private:int _shoesBase;
};class NikeShoes :public ShoesBase
{
public:NikeShoes(){cout << "NikeShoes() called"<<endl;}virtual ~NikeShoes(){cout << "~NikeShoes() called"<<endl;}void ShowTag() override {cout << "NikeShoes::ShowTag() called"<<endl;}private:};class AdidasShoes: public ShoesBase
{
public:AdidasShoes(){cout << "AdidasShoes() called"<<endl;}virtual ~AdidasShoes(){cout << "~AdidasShoes() called"<<endl;}void ShowTag() override {cout << "AdidasShoes::ShowTag() called"<<endl;}};class HuiLiShoes: public ShoesBase
{
public:HuiLiShoes(){cout << "HuiLiShoes() called"<<endl;}virtual ~HuiLiShoes(){cout << "~HuiLiShoes() called"<<endl;}void ShowTag() override {cout << "HuiLiShoes::ShowTag() called"<<endl;}};class ShoesFactory
{
public:ShoesFactory(){cout << "ShoesFactory() called"<<endl;}virtual ~ShoesFactory(){cout << "~ShoesFactory() called"<<endl;}std::shared_ptr<ShoesBase> CreateShoes(eShoesType shoesType);};#endif


examStu.cpp

#include
#include
#include
#include"examStu.h"using namespace std;std::shared_ptr<ShoesBase> ShoesFactory::CreateShoes(eShoesType shoesType)
{cout << "create sheoes class"<<endl;std::shared_ptr<ShoesBase> pShoes &＃61; nullptr;switch(shoesType){case SHOES_TYPE_NIKE:cout << "create nike class "<<endl;pShoes &＃61; std::make_shared<NikeShoes>();break;case SHOES_TYPE_ADIDAS:cout << "create AdidasShoes class"<<endl;pShoes &＃61; std::make_shared<AdidasShoes>();break; case SHOES_TYPE_HUILI:cout << "create HuiLiShoes class"<<endl;pShoes &＃61; std::make_shared<HuiLiShoes>();break; default:cout << "create shoes type not found!!"<<endl;break;}if(pShoes &＃61;&＃61; nullptr){cout << "create shoes class error!!"<<endl;}return pShoes;
}


main.cpp

#include
#include
#include
#include "examStu.h"using namespace std;int main(int argc, char *argv[])
{ShoesFactory shoesFactory;std::shared_ptr<ShoesBase> pHuiLishoes &＃61; shoesFactory.CreateShoes(SHOES_TYPE_HUILI);pHuiLishoes->ShowTag(); std::shared_ptr<ShoesBase> pNikeshoes &＃61; shoesFactory.CreateShoes(SHOES_TYPE_NIKE);pNikeshoes->ShowTag();std::shared_ptr<ShoesBase> pAdidasshoes &＃61; shoesFactory.CreateShoes(SHOES_TYPE_ADIDAS);pAdidasshoes->ShowTag();return 0;
}