1. 意图
定义一些列的算法,把它们一个个封装起来,并且使它们可相互替换。本模式使得算法可独立于使用它的客户而变化。
2. 别名
政策(Policy)
3. 结构
4. 例子
//策略基类
class Strategy
{
public:
Strategy(){};
~Strategy(){};
virtual void tax(int a,int b)=0;
};
//策略子类,不同的方法实现
class CN_Tax : public Strategy
{
public:
CN_Tax(){};
~CN_Tax(){};
void tax(int a,int b)
{
cout<<"CN_Tax:"<<(a*10+b)<<endl;
}
};
class USA_Tax : public Strategy
{
public:
USA_Tax(){};
~USA_Tax(){};
void tax(int a,int b)
{
cout<<"USA_Tax:"<<(a*8+b)<<endl;
}
};
class FR_Tax : public Strategy
{
public:
FR_Tax(){};
~FR_Tax(){};
void tax(int a,int b)
{
cout<<"FR_Tax:"<<(a*5+b)<<endl;
}
};
//调度类
class Context
{
public:
Context(Strategy* str){strategy=str;};
~Context(){};
void Useit(int num1,int num2){return strategy->tax(num1,num2);};
private:
Strategy* strategy;
};
int main()
{
Strategy* strategy=new CN_Tax();
Context* con=new Context(strategy);
con->Useit(3,5);
//策略A和策略B、策略C可替换
strategy =new USA_Tax();
con= new Context(strategy);
con->Useit(3,5);
strategy =new FR_Tax();
con= new Context(strategy);
con->Useit(3,5);
return 0;
}