通用Gate方式的FSM接口，
//-------------------------------------------#include "IGateState.h"#include <assert.h>#include <iostream.h>//-------------------------------------------
//-------------------------------------------class IGateFSM {public: IGateFSM(); virtual ~IGateFSM();
public:
inline void SetState(IGateState * state) {_state = state;}
virtual void OnEvent(ENUM_EVENT event); private: IGateState * _state;};//-------------------------------------------
// 派生类的实现，以地铁十字专门为模型，提供Lock/UnLock等与业务相关的方法
//-------------------------------------------
class VGateFSM : public IGateFSM{public: VGateFSM() {} virtual ~VGateFSM() {}
public:
void Lock(); void UnLock(); void Alarm(); void Thanks();
private: bool m_IsLock;
};//-------------------------------------------
//================================// ´代表状态类的抽象接口class IGateFSM;
// 事件描述enum ENUM_EVENT{ EVENT_COIN, // ͶÈëÓ²±Òʼþ EVENT_PASS // ´©Ô½Ê¼þ};
class IGateState {public: IGateState(); virtual ~IGateState();
public: virtual void OnEvent(ENUM_EVENT event, IGateFSM * fsm) = 0;
};//------------------------------------------
// State模式的实现类，代表两种状态
class VGateLock : public IGateState{public: static IGateState * Instance();
public: virtual void OnEvent(ENUM_EVENT event, IGateFSM * fsm); private: VGateLock(){}
static VGateLock * _instance;
};//------------------------------------------class VGateUnLock : public IGateState{public: static IGateState * Instance();
public: virtual void OnEvent(ENUM_EVENT event, IGateFSM * fsm);
private: VGateUnLock(){}
static VGateUnLock * _instance;
};
// FSM的实现
//-------------------------------------------IGateFSM::IGateFSM(){ _state = NULL;}IGateFSM::~IGateFSM(){}//-------------------------------------------void IGateFSM::OnEvent(ENUM_EVENT event){ assert(_state != NULL);
_state->OnEvent(event,this);}//-------------------------------------------void VGateFSM::Lock(){ this->m_IsLock = true;
cout<<"Lock the gate."<<endl;}//-------------------------------------------void VGateFSM::UnLock(){ this->m_IsLock = true; cout<<"Unlock the gate."<<endl;}//-------------------------------------------void VGateFSM::Alarm(){ cout<<"You should insert a coin."<<endl;}//-------------------------------------------void VGateFSM::Thanks(){ cout<<"Thank You for pay again."<<endl;}//-------------------------------------------
// state的实现部分
VGateLock * VGateLock::_instance = NULL;VGateUnLock * VGateUnLock::_instance = NULL;void VGateLock::OnEvent(ENUM_EVENT event, IGateFSM * fsm){ VGateFSM * vfsm = (VGateFSM *) fsm;
if (event == EVENT_PASS) { vfsm->Alarm(); return ; } if (event == EVENT_COIN) vfsm->UnLock();
vfsm->SetState(VGateUnLock::Instance());
}//-------------------------------------------void VGateUnLock::OnEvent(ENUM_EVENT event, IGateFSM * fsm){ VGateFSM * vfsm = (VGateFSM *) fsm;
if (event == EVENT_COIN) { vfsm->Thanks(); return ; } if (event == EVENT_PASS) vfsm->Lock();
vfsm->SetState(VGateLock::Instance());}//-------------------------------------------IGateState * VGateLock::Instance(){ if (_instance == NULL) _instance = new VGateLock();
return _instance;}//-------------------------------------------IGateState * VGateUnLock::Instance(){ if (_instance == NULL) _instance = new VGateUnLock();
return _instance;}//-------------------------------------------
测试程序：
int main(int argc, char* argv[]){ printf("FSM Demo:/n/n");
VGateFSM * _fsm = new VGateFSM();
_fsm->SetState(VGateLock::Instance());
_fsm->OnEvent(EVENT_PASS); _fsm->OnEvent(EVENT_COIN); _fsm->OnEvent(EVENT_COIN); _fsm->OnEvent(EVENT_PASS);
delete _fsm;
printf("/n"); return 0;}
可以看到输出为：
You should insert a coin.
Unlock the gate
Thank You for pay again.
Lock the gate.
与预期结果一样
小结：
有限状态机是OO中的一种建模方法，是以状态对象角度来分析解决问题，最主要的是通过建立抽象的状态类，以及相关的实现类，把状态的处
理，转换在派生类中实现，从而实现比较良好的逻辑与实现分开。
另：结构上与Strategy,Observer都类似，看来模式也不用记得那么死，其实都有相通的地方。。
UML图片咋粘贴不上来？怪。
