1 class Strategy 2 { 3 public: 4     Strategy() {} 5  6     virtual void AlgrithmInterface() = 0;    //算法族接口 7  8     virtual ~Strategy() 9     {10         cout << "Strategy Destruction called." << endl;11     }12 };13 14 class ConcrateStrategyA : public Strategy15 {16 public:17     ConcrateStrategyA() {}18 19     virtual void AlgrithmInterface()20     {21         cout << "ConcrateStrategyA AlgrithmInterface Called." << endl;22     }23 24     virtual ~ConcrateStrategyA()25     {26         cout << "ConcrateStrategyA Destruction called" << endl;27     }28 };29 30 class ConcrateStrategyB : public Strategy31 {32 public:33     ConcrateStrategyB() {}34 35     virtual void AlgrithmInterface()36     {37         cout << "ConcrateStrategyB AlgrithmInterface Called." << endl;38     }39 40     virtual ~ConcrateStrategyB()41     {42         cout << "ConcrateStrategyB Destruction Called" << endl;43     }44 };45 46 47 class Context48 {49 public:50     Context(Strategy *pStrategy)51     {52         mStrategy = pStrategy;53     }54 55     void DoAction()56     {57         if (mStrategy)58         {59             mStrategy->AlgrithmInterface();60         }61     }62 63     void SetStrategy(Strategy *pStrategy)64     {65         mStrategy = pStrategy;66     }67     ~Context()68     {69         if (mStrategy)70         {71             delete mStrategy;72             mStrategy = NULL;73         }74     }75 private:76     Strategy *mStrategy;77 };78 79 int _tmain(int argc, _TCHAR* argv[])80 {81     ConcrateStrategyA *strategyA = new ConcrateStrategyA;82     ConcrateStrategyB *strategyB = new ConcrateStrategyB;83     Context context(strategyA);84     context.DoAction();85 86     context.SetStrategy(strategyB);87     context.DoAction();88 89     delete strategyA;90     strategyA = NULL;91     delete strategyB;92     strategyB = NULL;93     getchar();94     return 0;95 }