C++二十三种设计模式之建造者模式

一、组成

抽象产品类：声明具体产品类功能接口。
具体产品类：实现抽象产品的功能接口。
抽象建造者类：持有产品类的引用，声明创建产品各个部件的接口。
具体建造者类：实现创建具体产品各个部件的接口。

二、特点

1、抽象建造者的产品引用以受保护的权限给子类继承。
2、所有产品都具备一样的结构，一个具体产品都有一个具体建造者。

三、目的

将构建过程和表示分离，使得同样的构建过程可以创建不同的表示。

四、缺点

1、灵活性限制问题，指挥者的构建过程固定限制了灵活性。

五、示例代码

#include<iostream>
#include <vector>
#include <list>
#include <string>
#include <mutex>
#include <map>
#include<stack>

using namespace std;

class Monster;//抽象产品类
class M_Undead;//具体产品类
class M_Element;//具体产品类
class M_Mechanic;//具体产品类
class MonsterBuilder;//抽象建造者类
class MBuilder_Undead;//具体建造者
class MBuilder_Element;//具体建造者
class MBuilder_Mechanic;//具体建造者

class Monster {
public:
	virtual ~Monster() {};
	virtual void print() = 0;
};

class M_Undead : public Monster {
public:
	~M_Undead() {
		cout << "~M_Undead" << endl;
	};
	void print() {
		cout << "Undead Monster" << endl;
	}
};

class M_Element : public Monster {
public:
	~M_Element() {
		cout << "~M_Element" << endl;
	};
	void print() {
		cout << "Element Monster" << endl;
	}
};

class M_Mechanic : public Monster {
public:
	~M_Mechanic() {
		cout << "~M_Mechanic" << endl;
	};
	void print() {
		cout << "Mechanic Monster" << endl;
	}
};

class MonsterBuilder {
public:
	Monster* GetResult() {
		return m_monster.get();
	}
	virtual void loadTrunkModel(string strno) = 0;
	virtual void loadHeadModel(string strno) = 0;
	virtual void loadLimbsModel(string strno) = 0;
	virtual ~MonsterBuilder() {};
protected:
	unique_ptr<Monster> m_monster;
};

class MBuilder_Undead : public MonsterBuilder {
public:
	MBuilder_Undead() {
		m_monster = make_unique<M_Undead>();
	}
	Monster* GetResult() {
		return m_monster.get();
	}
	void loadTrunkModel(string strno) {
		cout << "Undead Monster " << strno << " load trunk model" << endl;
	};
	void loadHeadModel(string strno) {
		cout << "Undead Monster " << strno << " load head model" << endl;
	};
	void loadLimbsModel(string strno) {
		cout << "Undead Monster " << strno << " load limbs model" << endl;
	};
	~MBuilder_Undead() {
		cout << "~MBuilder_Undead" << endl;
	};
};

class MBuilder_Element : public MonsterBuilder {
public:
	MBuilder_Element() {
		m_monster = make_unique<M_Element>();
	}
	Monster* GetResult() {
		return m_monster.get();
	}
	void loadTrunkModel(string strno) {
		cout << "Element Monster " << strno << " load trunk model" << endl;
	};
	void loadHeadModel(string strno) {
		cout << "Element Monster " << strno << " load head model" << endl;
	};
	void loadLimbsModel(string strno) {
		cout << "Element Monster " << strno << " load limbs model" << endl;
	};
	~MBuilder_Element() {
		cout << "~MBuilder_Element" << endl;
	};
};

class MBuilder_Mechanic : public MonsterBuilder {
public:
	MBuilder_Mechanic() {
		m_monster = make_unique<M_Mechanic>();
	}
	Monster* GetResult() {
		return m_monster.get();
	}
	void loadTrunkModel(string strno) {
		cout << "Mechanic Monster " << strno << " load trunk model" << endl;
	};
	void loadHeadModel(string strno) {
		cout << "Mechanic Monster " << strno << " load head model" << endl;
	};
	void loadLimbsModel(string strno) {
		cout << "Mechanic Monster " << strno << " load limbs model" << endl;
	};
	~MBuilder_Mechanic() {
		cout << "~MBuilder_Mechanic" << endl;
	};
};

class MonsterDirector {
public:
	MonsterDirector(MonsterBuilder* pMonsterBuilder) : m_monsterBuilder(pMonsterBuilder) {}
	Monster* Construct(string strModelNo) {
		m_monsterBuilder->loadHeadModel(strModelNo);
		m_monsterBuilder->loadTrunkModel(strModelNo);
		m_monsterBuilder->loadLimbsModel(strModelNo);
		return m_monsterBuilder->GetResult();
	}
	void SetBuilder(MonsterBuilder* pMonsterBuilder) {
		m_monsterBuilder = pMonsterBuilder;
	}
private:
	MonsterBuilder* m_monsterBuilder;
};
int main() {
	unique_ptr<MBuilder_Undead> mBuilder_Undead = make_unique<MBuilder_Undead>();
	unique_ptr<MBuilder_Element> mBuilder_Element = make_unique<MBuilder_Element>();
	unique_ptr<MBuilder_Mechanic> mBuilder_Mechanic = make_unique<MBuilder_Mechanic>();

	unique_ptr<MonsterDirector> monsterDirector = make_unique<MonsterDirector>(mBuilder_Undead.get());

	Monster* m_undead = monsterDirector->Construct("Undead");
	m_undead->print();

	monsterDirector->SetBuilder(mBuilder_Element.get());
	Monster* m_element = monsterDirector->Construct("Element");
	m_element->print();

	monsterDirector->SetBuilder(mBuilder_Mechanic.get());
	Monster* m_mechanic = monsterDirector->Construct("Mechanic");
	m_mechanic->print();

}