设计模式Before-after之工厂方法模式_before after 工厂-优快云博客

本文通过具体的代码示例介绍了如何使用工厂模式和抽象类来实现水果类别的扩展与实例化，展示了良好的代码组织方式及面向对象编程的思想。

before.cxx

#include <iostream>
#include <string>

class Apple {
public:
	void sayHello(void) {
		std::cout << "Hello, I'm a apple." << std::endl;
	}
};

class Banana {
public:
	void sayHello(void) {
		std::cout << "Hello, I'm a banana." << std::endl;
	}
};

class Pear {
public:
	void sayHello(void) {
		std::cout << "Hello, I'm a pear." << std::endl;
	}
};

int main(void) {
	Apple apple;
	apple.sayHello();

	// Banana banana;
	// banana.sayHello();

	// Pear pear;
	// pear.sayHello();
	return 0;
}

after.cxx

#include <iostream>
#include <string>
#include "config.hxx"

class Fruit {
public:
	virtual void sayHello(void) = 0;
};

class Apple: public Fruit {
	void sayHello(void) {
		std::cout << "Hello, I'm a apple." << std::endl;
	}
};

class Banana: public Fruit {
public:
	void sayHello(void) {
		std::cout << "Hello, I'm a banana." << std::endl;
	}
};

class Pear: public Fruit {
public:
	void sayHello(void) {
		std::cout << "Hello, I'm a pear." << std::endl;
	}
};

class FruitFactory {
public:
	virtual Fruit *createFruit(void) = 0;
};

class AppleFactory: public FruitFactory {
public:
	Fruit *createFruit(void) {
		return new Apple();
	}
};

class BananaFactory: public FruitFactory {
public:
	Fruit *createFruit(void) {
		return new Banana();
	}
};

class PearFactory: public FruitFactory {
public:
	Fruit *createFruit(void) {
		return new Pear();
	}
};

int main(void) {
	FruitFactory *fruitFactory = &_FRUIT_FACTORY_();
	Fruit *fruit = fruitFactory->createFruit();
	fruit->sayHello();
	delete fruit;
	return 0;
}

config.hxx

#define _FRUIT_FACTORY_ AppleFactory

// #define _FRUIT_FACTORY_ BananaFactory

// #define _FRUIT_FACTORY_ PearFactory