设计模式之: 策略模式

#include<iostream>
using namespace std;

enum strategy { 
	Strategy1;
	Strategy2;
	Strategy3;
 };

//Context：使用一个ConcreteStrategy对象来配置；维护一个对Stategy对象的引用，同时，可以定义一个接口来让Stategy访问它的数据。
class context
{
public:
	 context(strategy type)
	 {
	 	switch type
	 	{
	 			case Strategy1:
	 				pStrategy=new ConcreteStrategy1();
	 				break;
	 			case Strategy2:
	 				pStrategy=new ConcreteStrategy2();
	 				break;
	 			case Strategy3:
	 				pStrategy=new ConcreteStrategy3();
	 				break;
	 			default:
	 				break;

	 	}

	 };
	~ context(){delete pStrategy;};
	virtual void ContextInterface(){
		if (pStrategy)
            pStrategy->alogrithmInterface();
	};

private:
	Strategy* pStrategy;
	/* data */

};

//策略基类
class Strategy
{
public:
	Strategy();
	~Strategy();
	virtual void alogrithmInterface()=0;

	/* data */
};

//具体策略1
class ConcreteStrategy1:Strategy
{
public:
	ConcreteStrategy1();
	~ConcreteStrategy1();
	void alogrithmInterface()
	 {
	 	cout<<"Im ConcreteStrategy1!"

	 }
	/* data */
};
//具体策略2
class ConcreteStrategy2:Strategy
{
public:
	ConcreteStrategy2();
	~ConcreteStrategy2();
	void alogrithmInterface()
	 {
	 	cout<<"Im ConcreteStrategy2!"

	 }
	/* data */
};
//具体策略3
class ConcreteStrategy3:Strategy
{
public:
	ConcreteStrategy3();
	~ConcreteStrategy3();
	void alogrithmInterface()
	 {
	 	cout<<"Im ConcreteStrategy3!"

	 }
	/* data */
};

int main(int argc, char const *argv[])
{
	context* cont=new context(Strategy1);
	cont->ContextInterface();
	delete cont;
	cont=NULL;

	cont=new context(Strategy2);
	cont->ContextInterface();
	delete cont;
	cont=NULL;

	cont=new context(Strategy3);
	cont->ContextInterface();
	delete cont;
	cont=NULL;

	return 0;
}