设计模式(8)-工厂模式(Factory)

【描述】工厂模式有3种类型：简单工厂，工厂方法，抽象工厂。这3种设计模式都属于创建型的设计模式。简单工厂的工厂是具象的，没有抽象的工厂类。工厂方法，定义了一个创建对象的接口，让子类来决定具体实例化哪一个类。抽象工厂模式面对的问题是多产品等级结构的系统设计。相对于简单工厂，工厂方法和抽象工厂都定义了抽象的工厂类。工厂方法与抽象工厂的区别在于：工厂方法的“工厂”只制造单一的“产品”，而抽象工厂可以制造一族“产品”。

1 简单工厂（Simple Factory）

【UML图】

图1 简单工厂

1 定义了一个具象的工厂Factory；

2 定义了一个抽象的产品Product以及两个具象的产品ProductA，ProductB，实现了产品的方法operation；

3 Factory将根据需要选择制造具象的产品。(注意是具象的产品，策略模式以及建造模式Client调用的是抽象的接口，这是工厂模式与策略模式、建造模式关键区别，下同)

 

【代码清单】

common.h

#ifndef COMMON_H#define COMMON_Henum {Product_A = 0, Product_B = 1};#endif // COMMON_H

product.h

#ifndef PRODUCT_H#define PRODUCT_Hclass Product{public:    Product();public:    virtual void operation();};#endif // PRODUCT_H

producta.h

#ifndef PRODUCTA_H#define PRODUCTA_H#include "product.h"class ProductA : public Product{public:    ProductA();public:    void operation();};#endif // PRODUCTA_H

productb.h

#ifndef PRODUCTB_H#define PRODUCTB_H#include "product.h"class ProductB : public Product{public:    ProductB();public:    void operation();};#endif // PRODUCTB_H

simplefactory.h

#ifndef SIMPLEFACTORY_H#define SIMPLEFACTORY_H#include "product.h"class SimpleFactory{public:    SimpleFactory();public:    Product* createProduct(int type);};#endif // SIMPLEFACTORY_H

product.cpp

#include <QDebug>#include "product.h"Product::Product(){    qDebug()<<"construct Product";}void Product::operation(){    qDebug()<<"Product operation";}

producta.cpp

#include <QDebug>#include "producta.h"ProductA::ProductA(){    qDebug()<<"construct ProductA";}void ProductA::operation(){    qDebug()<<"ProductA::operation";}

productb.cpp

#include <QDebug>#include "productb.h"ProductB::ProductB(){    qDebug()<<"construct ProductB";}void ProductB::operation(){    qDebug()<<"ProductA::operation";}

simplefactory.cpp

#include <QDebug>#include "common.h"#include "simplefactory.h"#include "producta.h"#include "productb.h"SimpleFactory::SimpleFactory(){}Product* SimpleFactory::createProduct(int type){    Product *p = NULL;    switch(type)    {    case Product_A:        p = new ProductA;        break;    case Product_B:        p = new ProductB;        break;    default:;    }    return p;}

 

main.cpp

#include "simplefactory.h"#include "product.h"#include "common.h"int main(int argc, char **argv){    SimpleFactory *factory = new SimpleFactory;    Product * product = factory->createProduct(Product_A);    product->operation();    return 0;}

【运行结果】

construct Product construct ProductA ProductA::operation 

2 工厂方法(Factory Method)

【UML图】

图2 工厂方法

1 定义了一个抽象的工厂Factory以及两个具象的工厂，实现了产品制造的方法createProduct()；

2 定义了一个抽象的产品Product以及两个具象的产品ProductA，ProductB，实现了产品的方法operation；

3 Factory将根据需要选择制造具象的产品。

【代码清单】

factory.h

#ifndef FACTORY_H#define FACTORY_H#include "product.h"class Factory{public:    Factory();public:    virtual Product *createProduct();};#endif // FACTORY_H

factorya.h

#ifndef FACTORYA_H#define FACTORYA_H#include "factory.h"#include "producta.h"class FactoryA : public Factory{public:    FactoryA();public:    ProductA *createProduct();};#endif // FACTORYA_H

factoryb.h

#ifndef FACTORYB_H#define FACTORYB_H#include "factory.h"#include "productb.h"class FactoryB : public Factory{public:    FactoryB();public:    ProductB *createProduct();};#endif // FACTORYB_H

product.h

#ifndef PRODUCT_H#define PRODUCT_Hclass Product{public:    Product();public:    virtual void operation();};#endif // PRODUCT_H

producta.h

#ifndef PRODUCTA_H#define PRODUCTA_H#include "product.h"class ProductA : public Product{public:    ProductA();public:    void operation();};#endif // PRODUCTA_H

productb.h

#ifndef PRODUCTB_H#define PRODUCTB_H#include "product.h"class ProductB : public Product{public:    ProductB();public:    void operation();};#endif // PRODUCTB_H

factory.cpp

#include <QDebug>#include "factory.h"Factory::Factory(){    qDebug()<<"construct Factory";}Product *Factory::createProduct(){    return new Product;}

factorya.cpp

#include <QDebug>#include "factorya.h"FactoryA::FactoryA(){     qDebug()<<"construct FactoryA";}ProductA *FactoryA::createProduct(){    return new ProductA;}

factoryb.cpp

#include <QDebug>#include "factoryb.h"FactoryB::FactoryB(){     qDebug()<<"construct FactoryB";}ProductB* FactoryB::createProduct(){    return new ProductB;}

product.cpp

#include <QDebug>#include "product.h"Product::Product(){    qDebug()<<"construct Product";}void Product::operation(){    qDebug()<<"Product Operation";}

producta.cpp

#include <QDebug>#include "producta.h"ProductA::ProductA(){    qDebug()<<"construct ProductA";}void ProductA::operation(){    qDebug()<<"ProductA operation";}

productb.cpp

#include <QDebug>#include "productb.h"ProductB::ProductB(){    qDebug()<<"construct ProductB";}void ProductB::operation(){    qDebug()<<"ProductB operation";}

main.cpp

#include "factory.h"#include "factorya.h"#include "factoryb.h"#include "product.h"int main(int argc, char **argv){    Factory *factory = new FactoryA;    Product *product = factory->createProduct();    product->operation();    return 0;}

【运行结果】

construct Factory construct FactoryA construct Product construct ProductA ProductA operation 

3 抽象工厂(Abstract Factory)

【UML图】

图3 抽象工厂

1 定义了一个抽象的工厂Factory以及两个具象的工厂，实现了产品制造的方法createProductA()，createProductB；

2 定义了一个抽象的产品Product以及两个具象的产品ProductA，ProductB，实现了产品的方法operationA，operationB；

3 Factory将根据需要选择制造一族具象的产品。

 

【代码清单】

factory.h

#ifndef FACTORY_H#define FACTORY_H#include "product.h"class Factory{public:    Factory();public:    virtual Product *createProductA();    virtual Product *createProductB();};#endif // FACTORY_H

factorya.h

#ifndef FACTORYA_H#define FACTORYA_H#include "factory.h"#include "producta.h"#include "productb.h"class FactoryA : public Factory{public:    FactoryA();public:    ProductA *createProductA();    ProductB *createProductB();};#endif // FACTORYA_H

factoryb.h

#ifndef FACTORYB_H#define FACTORYB_H#include "factory.h"#include "producta.h"#include "productb.h"class FactoryB : public Factory{public:    FactoryB();public:    ProductA *createProductA();    ProductB *createProductB();};#endif // FACTORYB_H

product.h

#ifndef PRODUCT_H#define PRODUCT_Hclass Product{public:    Product();public:    virtual void operationA();    virtual void operationB();};#endif // PRODUCT_H

producta.h

#ifndef PRODUCTA_H#define PRODUCTA_H#include "product.h"class ProductA : public Product{public:    ProductA();public:    void operationA();};#endif // PRODUCTA_H

productb.h

#ifndef PRODUCTB_H#define PRODUCTB_H#include "product.h"class ProductB : public Product{public:    ProductB();public:    void operationB();};#endif // PRODUCTB_H

 

factory.cpp

#include <QDebug>#include "factory.h"Factory::Factory(){    qDebug()<<"construct Factory";}Product *Factory::createProductA(){    return new Product;}Product *Factory::createProductB(){    return new Product;}

factorya.cpp

#include <QDebug>#include "factorya.h"FactoryA::FactoryA(){     qDebug()<<"construct FactoryA";}ProductA *FactoryA::createProductA(){    return new ProductA;}ProductB *FactoryA::createProductB(){    return new ProductB;}

factoryb.cpp

#include <QDebug>#include "factoryb.h"FactoryB::FactoryB(){     qDebug()<<"construct FactoryB";}ProductA *FactoryB::createProductA(){    return new ProductA;}ProductB *FactoryB::createProductB(){    return new ProductB;}

product.cpp

#include <QDebug>#include "product.h"Product::Product(){    qDebug()<<"construct Product";}void Product::operationA(){    qDebug()<<"Product OperationA";}void Product::operationB(){    qDebug()<<"Product OperationB";}

producta.cpp

#include <QDebug>#include "producta.h"ProductA::ProductA(){    qDebug()<<"construct ProductA";}void ProductA::operationA(){    qDebug()<<"ProductA operation";}

productb.cpp

#include <QDebug>#include "productb.h"ProductB::ProductB(){    qDebug()<<"construct ProductB";}void ProductB::operationB(){    qDebug()<<"ProductB operation";}

main.cpp

#include "factory.h"#include "factorya.h"#include "factoryb.h"#include "product.h"int main(int argc, char **argv){    Factory *factory = new FactoryA;    Product *product = factory->createProductA();    product->operationA();    product = factory->createProductB();    product->operationB();    return 0;}

【运行结果】

construct Factory construct FactoryA construct Product construct ProductA ProductA operation construct Product construct ProductB ProductB operation 

 

【资源下载】

1 Qt设计模式1-8测试源码：http://download.csdn.net/detail/tandesir/4984275

*之所以发到第8篇博文，才放代码，是希望大家能动手实践。如利用VC平台实现设计模式。如果只是照搬，没有什么意义的。代码可能存在错误，设计模式理解可能也有偏差，恳请指正。
 声明：该源码仅供学习交流，勿用于商业目的。

 

 

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