Builder模式，也叫建造者模式，将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

enum EMouseType {
    USB = 1,
    PS2
}

// product
class Mouse {
    public:
        virtual void Input();
}

class MicrosoftMouse : public Mouse {
    public:
        virtual void Input();
        
    private:
        EMouseType type;
}

class LogitechMouse : public Mouse {
    public:
        virtual void Input();
        
    private:
        EMouseType type;
}

// builder
class MouseBuilder {
    public:
        virtual Mouse* GetMouse();
        virtual void SetType(EMouseType type);
}

class MicrosoftMouseBuilder: public MouseBuilder {
    public:
		MicrosoftMouseBuilder();
        virtual Mouse* GetMouse();
}

class LogitechMouseBuilder: public MouseBuilder {
    public:
		LogitechMouseBuilder();
        virtual Mouse* GetMouse();
}

// director
class Director {
    public:
        Director();
        MicrosoftMouse* GetMicrosoftMouse(EMouseType type);
        LogitechMouse*  GetLogitechMouse(EMouseType type);
        
    private:
        MicrosoftMouseBuilder* msBuilder;
        LogitechMouseBuilder*  lgBuilder;
}

Director::Director() {
    this->msBuilder = new MicrosoftMouseBuilder();
    this->lgBuilder = new LogitechMouseBuilder();
}

MicrosoftMouse* Director::GetMicrosoftMouse(EMouseType type) {
    this->msBuilder->SetType(type);
    this->msBuilder->GetMouse(type);
}

LogitechMouse* Director::GetLogitechMouse(EMouseType type) {
    this->lgBuilder->SetType(type);
    this->lgBuilder->GetMouse(type);    
}


// test
void Test() {
    Director* director = new Director();
    
    // product 10000 microsoft usb mouse
    for (int i = 0; i < 10000; i++) {
        director->GetMicrosoftMouse(EMouseType.USB);
    }
    
    // product 5000 microsoft PS2 mouse
    for (int i = 0; i < 5000; i++) {
        director->GetMicrosoftMouse(EMouseType.PS2);
    }
    
    
    // product 20000 logitech usb mouse
    for (int i = 0; i < 20000; i++) {
        director->GetLogitechMouse(EMouseType.USB);
    }
    
    // product 5000 logitech PS2 mouse
    for (int i = 0; i < 5000; i++) {
        director->GetLogitechMouse(EMouseType.PS2);
    }
    
    // todo ...  destroy
}

    PS. 我的设计模式系列blog，《设计模式》专栏，通过简单的示例演示设计模式，对于初学者很容易理解入门。深入学习请看GoF的《设计模式》。