建造者模式

使用场景：通常由几个部分（方法）组成，需求变化，但是这几个方法是不变的。网友给出了一个很好的例子——造小人：共六个部分，头部、身体、左右手、左右脚。不管需求怎么变化（胖小人和瘦小人），造小人就是这几个部分。建造者就是控制这一步步构造出产品的。

class Builder  
{
public:
	virtual void BuildHead() {}
	virtual void BuildBody() {}
	virtual void BuildLeftArm(){}
	virtual void BuildRightArm() {}
	virtual void BuildLeftLeg() {}
	virtual void BuildRightLeg() {}
};
//构造瘦人
class ThinBuilder : public Builder
{
public:
	void BuildHead() { cout<<"build thin body"<<endl; }
	void BuildBody() { cout<<"build thin head"<<endl; }
	void BuildLeftArm() { cout<<"build thin leftarm"<<endl; }
	void BuildRightArm() { cout<<"build thin rightarm"<<endl; }
	void BuildLeftLeg() { cout<<"build thin leftleg"<<endl; }
	void BuildRightLeg() { cout<<"build thin rightleg"<<endl; }
};
//构造胖人
class FatBuilder : public Builder
{
public:
	void BuildHead() { cout<<"build fat body"<<endl; }
	void BuildBody() { cout<<"build fat head"<<endl; }
	void BuildLeftArm() { cout<<"build fat leftarm"<<endl; }
	void BuildRightArm() { cout<<"build fat rightarm"<<endl; }
	void BuildLeftLeg() { cout<<"build fat leftleg"<<endl; }
	void BuildRightLeg() { cout<<"build fat rightleg"<<endl; }
};
//构造的指挥官
class Director  
{
private:
	Builder *m_pBuilder;
public:
	Director(Builder *builder) { m_pBuilder = builder; }
	void Create(){
		m_pBuilder->BuildHead();
		m_pBuilder->BuildBody();
		m_pBuilder->BuildLeftArm();
		m_pBuilder->BuildRightArm();
		m_pBuilder->BuildLeftLeg();
		m_pBuilder->BuildRightLeg();
	}
};

　　客户端使用方式：

int main()
{

       //造胖小人
	FatBuilder fat;
	Director director(&fat);
	director.Create();

      //造瘦小人
       //ThinBuilder thin;
       //Director director(&thin);
       //director.Create();
         
	return 0;
}