[C++知识库]C++设计模式之建造者模式

《大话设计模式》举了一个很好的例子——建造小人，一共需建造6个部分，头部、身体、左右手、左右脚。与工厂模式不同，建造者模式是在导向者的控制下一步一步构造产品的。建造小人就是在控制下一步步构造出来的。

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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();
	}
};

客户使用方式：

int main()
{
	FatBuilder thin;
	Director director(&thin);
	director.Create();
	return 0;
}