⼯⼚模式（C++实现）
  没事捣⿎了下相对⽽⾔⽐较简单的⼯⼚模式，然后写了个⼩Demo，记录下，等⼗年后看到也是种回忆哈.......
  ⼯⼚模式⼀般分为三种：简单⼯⼚模式、⼯⼚⽅法模式、抽象⼯⼚模式。
⼀、简单⼯⼚模式：
  简单⼯⼚模式，⼯⼚类是创建产品的，它决定创建哪⼀种产品，就像领导决定采⽤那种技术⽅案样。举个例⼦，现在有宝马车和奔驰车两种车需要⽣产，但是只有⼀个⼯⼚，且只能在同⼀时间⽣产⼀种车，这时就有⼯⼚决定⽣产那种车了。例⼦虽然不是⼗分恰当，但是会其意即可。我们直接看UML类图和代码吧。
看代码就⼀⽬了然了：
#include <iostream>
using namespace std;
enum CarType{BENZ, BMW};
class Car//车类
{
public:
virtual void createdCar(void) = 0;
};
class BenzCar : public Car //奔驰车
{
public:
BenzCar()
{
cout<<"Benz::Benz()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BenzCar::createdCar()"<<endl;
}
~BenzCar()
{
}
};
class BmwCar : public Car //宝马车
{
public:
BmwCar()
{
cout<<"Bmw::Bmw()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BmwCar::createdCar()"<<endl;
}
};
class CarFactory //车⼚
{
public:
Car* createSpecificCar(CarType type)
{
switch(type)
{
case BENZ://⽣产奔驰车
return (new BenzCar());
break;
case BMW://⽣⾠宝马车
return (new BmwCar());
break;
default:
return NULL;
break;
}
}
};
int main(int argc, char** argv)
{
CarFactory carfac;
Car* specificCarA = ateSpecificCar(BENZ);//看到⽹上众多⽰例在new后没有delete，感觉不是特别严谨
Car* specificCarB = ateSpecificCar(BMW);
delete specificCarA; delete specificCarB;
return0;
}
输出结果如下：
  简单⼯⼚模式在每次增加新的车型时，需要修改⼯⼚类，这就违反了开放封闭原则：软件实体（类、模块、函数）可以扩展，但是不可修改。于是，⼯⼚⽅法模式出现了。
⼆、⼯⼚⽅法模式：
  ⼯⼚⽅法模式：不再只由⼀个⼯⼚类决定那⼀个产品类应当被实例化，这个决定权被交给⼦类去做。当有新的产品（新型汽车）产⽣时，只要按照抽象产品⾓⾊、抽象⼯⼚⾓⾊提供的⽅法来⽣成即可（新车型可以⽤⼀个新类继承创建产品即可），那么就可以被客户使⽤，⽽不必去修改任何已有的代码。可以看出⼯⼚⾓⾊的结构也是符合开闭原则。如下⾯UML类图：
代码如下：
#include <iostream>
using namespace std;
class Car//车类
{
public:
virtual void createdCar(void) = 0;
奔驰与宝马};
class BenzCar : public Car //奔驰车
{
public:
BenzCar()
{
cout<<"Benz::Benz()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BenzCar::createdCar()"<<endl;
}
~BenzCar()
{
}
};
class BmwCar : public Car //宝马车
{
public:
BmwCar()
{
cout<<"Bmw::Bmw()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BmwCar::createdCar()"<<endl;
}
};
class Factory//车⼚
{
public:
virtual Car* createSpecificCar(void) = 0;
};
class BenzFactory : public Factory//奔驰车⼚
{
public:
virtual Car* createSpecificCar(void)
{
return (new BenzCar());
}
};
class BmwFactory : public Factory//宝马车⼚
{
public:
virtual Car* createSpecificCar(void)
{
return (new BmwCar());
}
};
int main(int argc, char** argv)
{
Factory* factory = new BenzFactory();
Car* specificCarA = factory->createSpecificCar();
factory = new BmwFactory();
Car* specificCarB = factory->createSpecificCar();
delete factory; delete specificCarA; delete specificCarB;
return0;
}
三、抽象⼯⼚：
  在上⾯的⼯⼚⽅法模式基础上，有需要⽣产⾼配版的奔驰和宝马，那⼯⼚⽅法模式就有点鞭长莫及了，这就⼜有抽象⼯⼚模式，UML类图如下：
代码如下：
#include <iostream>
using namespace std;
class Car//车类
{
public:
virtual void createdCar(void) = 0;
};
class BenzCar : public Car //奔驰车
{
public:
BenzCar()
{
cout<<"Benz::Benz()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BenzCar::createdCar()"<<endl;
}
~BenzCar()
{
}
};
class BmwCar : public Car //宝马车
{
public:
BmwCar()
{
cout<<"Bmw::Bmw()"<<endl;
}
virtual void createdCar(void)
{
cout<<"BmwCar::createdCar()"<<endl;
}
};
class HighCar //⾼配版车型
{
public:
virtual void createdCar(void) = 0;
};
class HighBenzCar : public HighCar //⾼配奔驰车
{
public:
HighBenzCar()
{
cout<<"HighBenzCarBenz::Benz()"<<endl;
}
virtual void createdCar(void)
{
cout<<"HighBenzCar::createdCar()"<<endl;
}
};
class HighBmwCar : public HighCar //⾼配宝马车
{
public:
HighBmwCar()
{
cout<<"HighBmwCar::Bmw()"<<endl;
}
virtual void createdCar(void)
{
cout<<"HighBmwCar::createdCar()"<<endl;
}
};
class Factory//车⼚
{
public:
virtual Car* createSpecificCar(void) = 0;
virtual HighCar* createdSpecificHighCar(void) = 0;
};
class BenzFactory : public Factory//奔驰车⼚
{
public:
virtual Car* createSpecificCar(void)
{
return (new BenzCar());
}
virtual HighCar* createdSpecificHighCar(void)
{
return (new HighBenzCar());
}
};
class BmwFactory : public Factory//宝马车⼚
{
public:
virtual Car* createSpecificCar(void)
{
return (new BmwCar());
}
virtual HighCar* createdSpecificHighCar(void)
{
return (new HighBmwCar());
}
};
int main(int argc, char** argv)
{
Factory* factory = new BenzFactory();
Car* specificCar = factory->createSpecificCar();
HighCar* spcificHighCar = factory->createdSpecificHighCar(); delete factory; delete specificCar; delete spcificHighCar; return0;
}
输出结果如下：
  以上代码在VC6.0上运⾏OK。