設(shè)計(jì)模式

單例模式

應(yīng)用：常用于管理資源剩蟀，如日志催蝗、線程池

class Singleton{
public:
    static Singleton& getInstance(){
        static Singleton instance;
        return instance;
    }
    void printTest(){
        cout<<"do something"<<endl;
    }
private:
    Singleton(){}//防止外部調(diào)用構(gòu)造創(chuàng)建對(duì)象
    Singleton(Singleton const &singleton);//阻止拷貝創(chuàng)建對(duì)象
    Singleton& operator=(Singleton const &singleton);//阻止賦值對(duì)象
};
int main()
{
    Singleton &a=Singleton::getInstance();
    a.printTest();
    return 0;
}

工廠模式

簡單工廠模式、工廠方法模式育特、抽象工廠模式
作用：封裝對(duì)象的創(chuàng)建丙号，分離對(duì)象的創(chuàng)建和操作過程，用于批量管理對(duì)象的創(chuàng)建過程缰冤，便于程序的維護(hù)和擴(kuò)展犬缨。

簡單工廠模式

//簡單工廠模式
typedef enum ProductTypeTag
{
    TypeA,
    TypeB,
    TypeC
}PRODUCTTYPE;

class Product//產(chǎn)品抽象基類
{
public:
    virtual void Show() = 0;
};

class ProductA : public Product
{
public:
    void Show()
    {
    cout<<"I'm ProductA"<<endl;
    }
};

class ProductB : public Product
{
public:
    void Show()
    {
    cout<<"I'm ProductB"<<endl;
    }
};
class ProductC : public Product
{
public:
    void Show()
    {
    cout<<"I'm ProductC"<<endl;
    }
};
class Factory//工廠類
{
    public:
    Product* CreateProduct(PRODUCTTYPE type)
    {
        switch (type)
    {
        case TypeA:
        return new ProductA();
        case TypeB:
        return new ProductB();
        case TypeC:
        return new ProductC();
        default:
        return NULL;
    }
    }
};
int main()
{
    Factory productCreator;
    Product *productA=productCreator.CreateProduct(TypeA);
    Product *productB=productCreator.CreateProduct(TypeB);
    Product *productC=productCreator.CreateProduct(TypeC);
    productA->Show();
    productB->Show();
    productC->Show();
if(productA){
    delete productA;
    productA=NULL;
}
if(productB){
    delete productB;
    productB=NULL;
}
if(productC){
    delete productC;
    productC=NULL;
}
return 0;
}

工廠方法模式
其實(shí)這才是正宗的工廠模式，簡單工廠模式只是一個(gè)簡單的對(duì)創(chuàng)建過程封裝棉浸。工廠方法模式在簡單工廠模式的基礎(chǔ)上增加對(duì)工廠的基類抽象怀薛，不同的產(chǎn)品創(chuàng)建采用不同的工廠創(chuàng)建（從工廠的抽象基類派生），這樣創(chuàng)建不同的產(chǎn)品過程就由不同的工廠分工解決：FactoryA專心負(fù)責(zé)生產(chǎn)ProductA迷郑，F(xiàn)actoryB專心負(fù)責(zé)生產(chǎn)ProductB枝恋，F(xiàn)actoryA和FactoryB之間沒有關(guān)系创倔；如果到了后期，如果需要生產(chǎn)ProductC時(shí)焚碌，我們則可以創(chuàng)建一個(gè)FactoryC工廠類畦攘，該類專心負(fù)責(zé)生產(chǎn)ProductC類產(chǎn)品。
該模式相對(duì)于簡單工廠模式的優(yōu)勢(shì)在于：便于后期產(chǎn)品種類的擴(kuò)展呐能。

//工廠方法模式
typedef enum ProductTypeTag
{
    TypeA,
    TypeB,
    TypeC
}PRODUCTTYPE;
class Product//產(chǎn)品抽象基類
{
    public:
    virtual void Show() = 0;
};
class ProductA : public Product
{
public:
    void Show()
    {
        cout<<"I'm ProductA"<<endl;
    }
};
class ProductB : public Product
{
public:
    void Show()
    {
        cout<<"I'm ProductB"<<endl;
    }
};
class Factory//工廠類
{
public:
    virtual Product *createProduct()=0;
};

class FactoryA:public Factory{
public:
    Product *createProduct(){
        return new ProductA();
    }
};

class FactoryB:public Factory{
public:
    Product *createProduct(){
        return new ProductB();
    }
};
class FactoryC:public Factory{
public:
    Product *createProduct(){
        return new ProductC();
    }
};
int main()
{
    Factory *factoryA=new FactoryA();
    Product *productA = factoryA->createProduct();
    productA->Show();
    Factory *factoryB=new FactoryB();
    Product *productB = factoryB->createProduct();
    productB->Show();
    if (factoryA)
    {
        delete factoryA;
        factoryA = NULL;
    }
    if (factoryB)
    {
        delete factoryB;
        factoryB = NULL;
    }
    if (productA)
    {
        delete productA;
        productA = NULL;
    }
    if (productB)
    {
        delete productB;
        productB = NULL;
    }
    return 0;
}

3.抽象工廠模式
抽象工廠模式對(duì)工廠方法模式進(jìn)行了更加一般化的描述。工廠方法模式適用于產(chǎn)品種類結(jié)構(gòu)單一的場(chǎng)合抑堡，為一類產(chǎn)品提供創(chuàng)建的接口摆出；而抽象工廠方法適用于產(chǎn)品種類結(jié)構(gòu)多的場(chǎng)合，就是當(dāng)具有多個(gè)抽象產(chǎn)品類型時(shí)首妖，抽象工廠便可以派上用場(chǎng)偎漫。

抽象工廠模式更適合實(shí)際情況，受生產(chǎn)線所限有缆，讓低端工廠生產(chǎn)不同種類的低端產(chǎn)品象踊，高端工廠生產(chǎn)不同種類的高端產(chǎn)品。

//抽象工廠模式
class ProductA
{
public:
    virtual void Show() = 0;
};

class ProductA1 : public ProductA//A類低端產(chǎn)品
{
public:
    void Show()
    {
        cout<<"I'm ProductA1"<<endl;
    }
};
class ProductA2 : public ProductA//A類高端產(chǎn)品
{
public:
    void Show()
    {
        cout<<"I'm ProductA2"<<endl;
    }
};
class ProductB
{
public:
    virtual void Show() = 0;
};

class ProductB1 : public ProductB//B類低端產(chǎn)品
{
public:
    void Show()
    {
        cout<<"I'm ProductB1"<<endl;
    }
};
class ProductB2 : public ProductB//B類高端產(chǎn)品
{
public:
    void Show()
    {
        cout<<"I'm ProductB2"<<endl;
    }
};
class Factory
{
public:
    virtual ProductA *CreateProductA() = 0;
    virtual ProductB *CreateProductB() = 0;
};
class Factory1 : public Factory//1號(hào)工廠用于生產(chǎn)低端產(chǎn)品
{
public:
    ProductA *CreateProductA()
    {
        return new ProductA1();
    }
    ProductB *CreateProductB()
    {
        return new ProductB1();
    }
};
class Factory2 : public Factory//2號(hào)工廠用于生產(chǎn)高端產(chǎn)品
{
    ProductA *CreateProductA()
    {
        return new ProductA2();
    }
    ProductB *CreateProductB()
    {
        return new ProductB2();
    }
};
int main()
{
    Factory *factory1 = new Factory1();
    ProductA *productA1 = factory1->CreateProductA();
    ProductB *productB1 = factory1->CreateProductB();
    productA1->Show();
    productB1->Show();
    Factory *factory2 = new Factory2();
    ProductA *productA2 = factory2->CreateProductA();
    ProductB *productB2 = factory2->CreateProductB();
    productA2->Show();
    productB2->Show();
if (factory1)
{
delete factory1;
factory1 = NULL;
}
if (productA1)
{
delete productA1;
productA1= NULL;
}
if (productB1)
{
delete productB1;
productB1 = NULL;
}
if (factory2)
{
delete factory2;
factory2 = NULL;
}
if (productA2)
{
delete productA2;
productA2 = NULL;
}
if (productB2)
{
delete productB2;
productB2 = NULL;
}
}