《大話設計模式》之 第6章 穿什麼有這麼重要？——裝飾模式 (Decorator 模式) 小結

今天看到裝飾者模式，中間提到了建造者模式，雖然還沒看過建造者模式，但是想想看就應該知道二者的區別：

前者是對象的組成是不固定的，比如一個person，想穿幾件clothes都可以，而建造者模式，就是所有的組成都必須是確定的，就好像某個型號的電腦，必須包含主板、顯卡、記憶體……

具體的應用還不太清晰。

但是原理基本上是這樣的：一個【基類Component】，提供統一的介面，子類主要分為【裝飾類DecoratorComponent】和【被裝飾類PersonComponent】

【DecoratorComponent】又可以派生子類【TShirtsDecoratorComponent】、【TrouserDecoratorComponent】……

用以裝飾PersonComponent類。

【基類Component】

//基類class Component{public:    Component(void);    virtual ~Component(void);    virtual void CommonInterface(void) const = 0;};Component::Component(void){    }Component::~Component(void){    }

【被裝飾類PersonComponent】

//被裝飾類class PersonComponent : public Component{public:    PersonComponent(void);    ~PersonComponent(void);    virtual void CommonInterface(void) const;};PersonComponent::PersonComponent(void){    }PersonComponent::~PersonComponent(void){    }void PersonComponent::CommonInterface(void) const{    std::cout << "被裝飾者 小菜\n";}

【裝飾類DecoratorComponent】

//裝飾類class DecoratorComponent : public Component{public:    DecoratorComponent(void);    virtual ~DecoratorComponent(void);    virtual void CommonInterface(void) const;    void setComponent(Component* comp);protected:    Component* component;};DecoratorComponent::DecoratorComponent(void){    }DecoratorComponent::~DecoratorComponent(void){    }void DecoratorComponent::CommonInterface(void) const{    if (this->component != NULL) {        component->CommonInterface();    }}void DecoratorComponent::setComponent(Component* comp){    this->component = comp;}

【裝飾子類TShirtsDecoratorComponent】

//裝飾子類TShirtsDecoratorComponentclass TShirtsDecoratorComponent : public DecoratorComponent{public:    TShirtsDecoratorComponent(void);    virtual ~TShirtsDecoratorComponent(void);    virtual void CommonInterface(void) const;};TShirtsDecoratorComponent::TShirtsDecoratorComponent(void){    }TShirtsDecoratorComponent::~TShirtsDecoratorComponent(void){    }void TShirtsDecoratorComponent::CommonInterface(void) const{    DecoratorComponent::CommonInterface();    std::cout << "TShirts Decorated!\n";}

【裝飾子類TrouserDecoratorComponent】

//裝飾子類TrouserDecoratorComponentclass TrouserDecoratorComponent : public DecoratorComponent{public:    TrouserDecoratorComponent(void);    virtual ~TrouserDecoratorComponent(void);    virtual void CommonInterface(void) const;};TrouserDecoratorComponent::TrouserDecoratorComponent(void){    }TrouserDecoratorComponent::~TrouserDecoratorComponent(void){    }void TrouserDecoratorComponent::CommonInterface(void) const{    DecoratorComponent::CommonInterface();    std::cout << "Trouser Decorated!\n";}

【main】

int main(int argc, const char * argv[]){    PersonComponent* person = new PersonComponent();    TShirtsDecoratorComponent* tShirts = new TShirtsDecoratorComponent();    TrouserDecoratorComponent* trouser = new TrouserDecoratorComponent();    tShirts->setComponent(person);    trouser->setComponent(tShirts);    trouser->CommonInterface();        delete trouser;    trouser = NULL;    delete tShirts;    tShirts = NULL;    delete person;    person = NULL;        return 0;}

【結果】

被裝飾者 小菜

TShirts Decorated!

Trouser Decorated!