设计模式-行为-Strategy（策略）模式

Strategy（策略）模式与 Template 模式目的相同，区别在于实现手法：Template 依赖继承，而 Strategy 采用组合，从而解决了继承带来的弊端。

问题背景

为了在业务逻辑（算法）的具体实现与抽象接口之间实现解耦，Strategy 模式将算法（业务逻辑）封装到一个 Context 类中，通过组合的方式持有算法对象，再通过委托将抽象接口的调用转发给具体的组合对象。State 模式与之有类似的区别。

Strategy 模式定义了一系列算法并将它们封装起来，使各算法可以相互替换，从而让算法的变化独立于使用它的客户。

示例 1：基本策略模式

#include "PublicHeaders.h"
                
                class Strategy
                {
                public:
                	virtual void AlgrithmInterface() = 0;
                };
                
                class ConCreateStrategy :public Strategy
                {
                public:
                	void AlgrithmInterface()override
                	{
                		cout << __FUNCTION__ << endl;
                	}
                
                };
                class Contex
                {
                public:
                	Contex(Strategy *strategy)
                	{
                		this->strategy = strategy;
                	}
                
                	void DoAction()
                	{
                		this->strategy->AlgrithmInterface();
                	}
                private:
                	Strategy*strategy;
                };
                
                
                /**
                 * @brief  test function for strategy pattern
                 */
                void testStrategy()
                {
                	Contex* contex = new Contex(new ConCreateStrategy);
                
                	contex->DoAction();
                
                }

示例 2：武器系统

class WeaponStrategy
                	{
                	public:
                		virtual void doFire() = 0;
                	};
                
                	class GaTlingGun_Strategy :public WeaponStrategy
                	{
                	public:
                		virtual void doFire()override
                		{
                
                
                		}
                
                	};
                
                	class PistolGun_Strategy :public WeaponStrategy
                	{
                	public:
                		virtual void doFire()override
                		{
                
                		}
                
                	};
                
                
                	class PlayerContex
                	{
                	public:
                		void Fire()
                		{
                			weapon->doFire();
                		}
                
                
                		void setWeapon(WeaponStrategy *strategy)
                		{
                			this->weapon = strategy;
                		}
                
                		WeaponStrategy*weapon;
                	};
                
                	void test()
                	{
                		PlayerContex*player = new PlayerContex;
                		player->setWeapon(new GaTlingGun_Strategy);
                
                		player->Fire();
                
                
                	}