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Strategy Pattern

1.Strategy模式和Template模式要解决的问题是相同（类似）的，都是为了给业务逻辑（算法）具体实现和抽象接口之间的解耦。Strategy模式将逻辑（算法）封装到一个类（Context）里面，通过组合的方式将具体算法的实现在组合对象中实现，再通过委托的方式将抽象接口的实现委托给组合对象实现.

2.Strategy Pattern 结构图

3.实现

 1 #ifndef _STRATEGY_H_ 
 2 #define _STRATEGY_H_
 3 
 4 class Strategy 
 5 { 
 6 public: 
 7     Strategy();
 8     virtual ~Strategy();
 9     virtual void AlgrithmInterface() = 0;
10 protected:
11 private:
12 };
13 
14 class ConcreteStrategyA:public Strategy 
15 { 
16 public: 
17     ConcreteStrategyA();
18     virtual ~ConcreteStrategyA();
19     void AlgrithmInterface();
20 protected:
21 private:
22 };
23 
24 class ConcreteStrategyB:public Strategy 
25 { 
26 public:
27     ConcreteStrategyB();
28     virtual ~ConcreteStrategyB();
29     void AlgrithmInterface();
30 protected:
31 private:
32 };
33 
34 #endif

strategy.h

 1 #include "Strategy.h" 
 2 #include <iostream> 
 3 using namespace std;
 4 
 5 Strategy::Strategy() 
 6 {
 7 
 8 }
 9 Strategy::~Strategy() 
10 { 
11     cout<<"~Strategy....."<<endl;
12 }
13 void Strategy::AlgrithmInterface() 
14 {
15 
16 }
17 ConcreteStrategyA::ConcreteStrategyA() 
18 {
19 
20 }
21 ConcreteStrategyA::~ConcreteStrategyA() 
22 { 
23     cout<<"~ConcreteStrategyA....."<<endl; 
24 }
25 void ConcreteStrategyA::AlgrithmInterface()
26 { 
27     cout<<"test ConcreteStrategyA....."<<endl;
28 }
29 ConcreteStrategyB::ConcreteStrategyB() 
30 {
31 
32 }
33 ConcreteStrategyB::~ConcreteStrategyB() 
34 {
35     cout<<"~ConcreteStrategyB....."<<endl; 
36 }
37 void ConcreteStrategyB::AlgrithmInterface() 
38 { 
39     cout<<"test ConcreteStrategyB....."<<endl; 
40 }

strategy.cpp

 1 #ifndef _CONTEXT_H_ 
 2 #define _CONTEXT_H_
 3 
 4 class Strategy;
 5 
 6 class Context 
 7 { 
 8 public:
 9     Context(Strategy* stg);
10     ~Context();
11     void DoAction(); 
12 protected:
13 private: 
14     Strategy* _stg;
15 };
16 
17 #endif

context.h

 1 #include "Context.h" 
 2 #include "Strategy.h" 
 3 #include <iostream> 
 4 using namespace std;
 5 
 6 Context::Context(Strategy* stg) 
 7 { 
 8     _stg = stg;
 9 }
10 Context::~Context() 
11 { 
12     if (!_stg) delete _stg; 
13 }
14 void Context::DoAction() 
15 { 
16     _stg->AlgrithmInterface();
17 }

context.cpp

 1 #include "Context.h" 
 2 #include "Strategy.h"
 3 #include <iostream>
 4 using namespace std;
 5 
 6 int main(int argc,char* argv[]) 
 7 { 
 8     Strategy* ps = new ConcreteStrategyA();
 9     Context* pc = new Context(ps);
10     pc->DoAction();
11     if (NULL != pc) 
12         delete pc;
13 
14     return 0; 
15 }

main.cpp

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原文地址：https://www.cnblogs.com/programmer-wfq/p/4667607.html