工厂方法模式
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工厂方法模式
工厂方法模式其实也很简单,先放一张UML类图来看一下类结构:
由图我们可以看出有两个基类:
- BaseFactory
- AppleFactory
- PearFactory
- Fruit
- Apple
- Pear
AppleFactory负责创建Apple类,PearFactory负责创建Pear类。下面放代码实现:
- fruit.h
#ifndef FRUIT_H
#define FRUIT_H
class Fruit
{
public:
Fruit();
virtual ~Fruit();
virtual void FruitType() = 0;
};
class Apple : public Fruit
{
public:
Apple();
virtual ~Apple() override;
virtual void FruitType() override;
};
class Pear : public Fruit
{
public:
Pear();
virtual ~Pear() override;
virtual void FruitType() override;
};
#endif // FRUIT_H
- fruit.cpp
#include <QDebug>
#include "fruit.h"
void Apple::FruitType()
{
qDebug() << "I am an Apple";
}
void Pear::FruitType()
{
qDebug() << "I am an Pear";
}
- basefactory.h
#include "fruit.h"
class BaseFactory
{
public:
BaseFactory();
virtual ~BaseFactory();
virtual Fruit* Produce() = 0;
protected:
Fruit* m_Fruit;
};
class AppleFactory : public BaseFactory
{
public:
AppleFactory();
virtual ~AppleFactory() override;
virtual Fruit* Produce() override;
};
class PearFactory : public BaseFactory
{
public:
PearFactory();
virtual ~PearFactory() override;
virtual Fruit* Produce() override;
};
#endif // BASEFACTORY_H
- basefactory.cpp
#include <QDebug>
#include "basefactory.h"
#define DELETEOBJECT(x) if(x != nullptr) { delete x; x = nullptr;}
BaseFactory::BaseFactory()
{
}
BaseFactory::~BaseFactory()
{
DELETEOBJECT(m_Fruit);
}
AppleFactory::AppleFactory()
{
}
AppleFactory::~AppleFactory()
{
}
Fruit *AppleFactory::Produce()
{
m_Fruit = new Apple();
return m_Fruit;
}
PearFactory::PearFactory()
{
}
PearFactory::~PearFactory()
{
}
Fruit *PearFactory::Produce()
{
m_Fruit = new Pear();
return m_Fruit;
}
- main.cpp
#include <QCoreApplication>
#include "basefactory.h"
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
BaseFactory* factory = new AppleFactory();
factory->Produce()->FruitType();
factory = new PearFactory();
factory->Produce()->FruitType();
return a.exec();
}
main函数只用到了BaseFactory基类工厂,很好的实现了细节的隐藏从而增加了代码的复用性。
工厂方法模式遵照了以下几个设计原则:
- 依赖倒转原则
- 开放封闭原则
- 迪米特法则
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