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作用：定义一系列的算法,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。
UML结构图：
解析：
简而言之一句话,Strategy模式是对算法的封装.处理一个问题的时候可能有多种算法,这些算法的接口(输入参数,输出参数等)都是一致的,那么可以考虑采用Strategy模式对这些算法进行封装,在基类中定义一个函数接口就可以了. 代码实现： Strategy.h
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2 #ifndef STRATEGY_H 3 #define STRATEGY_H 4 5 class Strategy; 6 7 class Context 8 { 9 public: 10 Context(Strategy *pStrategy); 11 ~Context(); 12 13 void ContextInterface(); 14 private: 15 Strategy* m_pStrategy; 16 }; 17 18 class Strategy 19 { 20 public: 21 virtual ~Strategy(){} 22 23 virtual void AlgorithmInterface() = 0; 24 }; 25 26 class ConcreateStrategyA 27 : public Strategy 28 { 29 public: 30 virtual ~ConcreateStrategyA(){} 31 32 virtual void AlgorithmInterface(); 33 }; 34 35 #endif 36 Strategy.cpp
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2 #include <iostream> 3 #include "Strategy.h" 4 5 Context::Context(Strategy *pStrategy) 6 : m_pStrategy(pStrategy) 7 { 8 } 9 10 Context::~Context() 11 { 12 delete m_pStrategy; 13 m_pStrategy = NULL; 14 } 15 16 void Context::ContextInterface() 17 { 18 if (NULL != m_pStrategy) 19 { 20 m_pStrategy->AlgorithmInterface(); 21 } 22 } 23 24 void ConcreateStrategyA::AlgorithmInterface() 25 { 26 std::cout << "AlgorithmInterface Implemented by ConcreateStrategyA\n"; 27 } 28 Main.cpp
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2 #include "Strategy.h" 3 4 int main() 5 { 6 Strategy* pStrategy = new ConcreateStrategyA(); 7 Context* pContext = new Context(pStrategy); 8 9 pContext->ContextInterface(); 10 11 delete pContext; 12 13 return 0; 14 } 15 (whiteyun) |
