设计模式之原型模式

【定义】用原型实例指定创建对象的种类，并且通过拷贝这些原型创建新的对象。

【情景】假设现在在一家公司应聘，对方要求填写求职信息表，多位面试官每人都要一份，需要手工填写。现在有两种方式可供选择：a、手工填写多份信息表;  2、手工填写一份，然后剩下的拿填写完得第一份复印。第二种方式就是这里所说的原型模式，第一份手工填写的信息表就是一个原型。一般在初始化的信息不发生变化的情况下，克隆是最好的办法。这既隐藏了对象创建的细节，有对性能大大的提高。

【UML】

【代码】

#include <string.h>
#include <iostream> 

using namespace std;

class Resume
{
protected:
	char* name;
public:
	Resume() {}
	virtual Resume* Clone() { return NULL; }
	virtual void SetName(char* name) {}
	virtual void Show() {}
};

class ConcreteResumeA : public Resume
{
public:
	ConcreteResumeA(char* name);
	ConcreteResumeA(ConcreteResumeA &a);
	~ConcreteResumeA();
	void SetName(char* name);
	Resume* Clone();
	void Show();
};

ConcreteResumeA::ConcreteResumeA(char* name)
{
	if(NULL == name)
	{
		this->name = new char[1];
		this->name[0] = '\0';
	}
	else
	{
		this->name = new char[strlen(name) + 1];
		strcpy(this->name, name);
	}
}

ConcreteResumeA::ConcreteResumeA(ConcreteResumeA &a)
{
	this->name = new char[strlen(a.name) + 1];
	strcpy(name, a.name);
}

ConcreteResumeA::~ConcreteResumeA()
{
	delete [] name;
}

void ConcreteResumeA::SetName(char* name)
{
	delete [] this->name;
	if(NULL == name)
	{
		this->name = new char[1];
		this->name[0] = '\0';
	}
	else
	{
		this->name = new char[strlen(name) + 1];
		strcpy(this->name, name);
	}
}

void ConcreteResumeA::Show()
{
	cout<<"ConcreteResumeA name: "<<name<<endl;
}

Resume* ConcreteResumeA::Clone()
{
	return new ConcreteResumeA(*this);
}

int main()
{
	Resume *a1 = new ConcreteResumeA("Resume A");
	Resume *a2 = a1->Clone();

	a1->Show();
	delete a1;

	a2->Show();
	delete a2;

	return 0;
}