State模式的应用探讨

//直接贴代码吧,欢迎提出缺点及改进方式
//StatePattern.h

#ifndef STATE_PATTERN_H

#define STATE_PATTERN_H

#include < iostream >

using namespace std;

typedef unsigned char BYTE;

class CScenario; // decl

class CSoldier

{

public:

CSoldier();

~CSoldier()

{};

CScenario* GetScenario();

void ChangeScenario(CScenario* scenario);

void HandleRequest(BYTE* req);//根据req请求决定采取的动作

protected:

CScenario* _scenario;

} ;

class CScenario // 处于的场景

{

public:

enum ActionType

{

AT_TELL_ON_ROAD = 0x01,

AT_TELL_IN_RIVER = 0x02,

AT_TELL_MEET_ENEMY = 0x04,

AT_TELL_INFO = 0x07,//上面三个的"组合"

AT_WALK = 0x08,

AT_SWIM = 0x10,

AT_FIRE = 0x20

};

public:

virtual void ChangeScenario(CSoldier* soldier,CScenario* scenario)

{}

virtual int GetSupportedAction()

{return 0;}

virtual void act(CSoldier*soldier, ActionType at)

{}//采取的动作

virtual void Walk()

{}//走路

virtual void Swim()

{}//游泳

virtual void Fire()

{}//开枪

protected:

CScenario()

{};

} ;

class CNoOp : public CScenario

{

public:

CNoOp()

{}

static CScenario* Instance();

void ChangeScenario(CSoldier* soldier,CScenario* scenario);

int GetSupportedAction();

void act(CSoldier*soldier,ActionType at);

private:

static CScenario* _instance;

} ;

class COnRoad : public CScenario

{

public:

static CScenario* Instance();

void ChangeScenario(CSoldier* soldier,CScenario* scenario);

void Walk();

int GetSupportedAction();

void act(CSoldier*soldier,ActionType at);

private:

static CScenario* _instance;

protected:

COnRoad()

{};//禁止直接定义对象

} ;

class CInRiver : public CScenario

{

public:

static CScenario* Instance();

void ChangeScenario(CSoldier* soldier,CScenario* scenario);

void Swim();

int GetSupportedAction();

void act(CSoldier*soldier,ActionType at);

private:

static CScenario* _instance;

protected:

CInRiver()

{};

} ;

class CMeetEnemy : public CScenario

{

public:

static CScenario* Instance();

void ChangeScenario(CSoldier* soldier,CScenario* scenario);

void Fire();

int GetSupportedAction();

void act(CSoldier*soldier,ActionType at);

private:

static CScenario* _instance;

protected:

CMeetEnemy()

{};

} ;

#endif

//StatePattern.cpp

#include " StatePattern.h "

CSoldier::CSoldier()

{

this->ChangeScenario(CNoOp::Instance());

}

CScenario * CSoldier::GetScenario()

{

return _scenario;

}

void CSoldier::ChangeScenario(CScenario * scenario)

{

this->_scenario = scenario;

}

void CSoldier::HandleRequest(BYTE * req)

{

if (req == NULL)

{

cout << "req == NULL" << endl;

return;

}

BYTE action = *req;//一个字节的Action类型

if (!(action & GetScenario()->GetSupportedAction()))//不支持该Action

{

cout << "不支持该操作类型" << endl;

return;

}

GetScenario()->act(this,(CScenario::ActionType)action);

return;

}

// 0.实现CNoOp，作为soldier的初始化状态

CScenario * CNoOp::_instance = NULL;

CScenario * CNoOp::Instance()

{

if (_instance == NULL)

{

_instance = new CNoOp();

}

return _instance;

}

void CNoOp::ChangeScenario(CSoldier * soldier,CScenario * scenario)

{

soldier->ChangeScenario(scenario);

return;

}

int CNoOp::GetSupportedAction()

{

return AT_TELL_INFO;

}

void CNoOp::act(CSoldier * soldier,ActionType at)

{

switch(at)

{

case AT_TELL_ON_ROAD:

cout << "---> on road" << endl;

soldier->ChangeScenario(COnRoad::Instance());

break;

case AT_TELL_IN_RIVER:

cout << "---> in river" << endl;

soldier->ChangeScenario(CInRiver::Instance());

break;

case AT_TELL_MEET_ENEMY:

cout << "---> meet enymy" << endl;

soldier->ChangeScenario(CMeetEnemy::Instance());

break;

default:

cout << "unkown action type" << endl;

break;

}

return;

}

// 1.实现COnRoad

CScenario * COnRoad::_instance = NULL;

CScenario * COnRoad::Instance()

{

if (_instance == NULL)

{

_instance = new COnRoad();

}

return _instance;

}

void COnRoad::Walk()

{

cout << "walk" << endl;

return;

}

int COnRoad::GetSupportedAction()

{

return AT_TELL_INFO | AT_WALK;

}

void COnRoad::ChangeScenario(CSoldier * soldier,CScenario * scenario)

{

soldier->ChangeScenario(scenario);

return;

}

void COnRoad::act(CSoldier * soldier,ActionType at)

{

switch(at)

{

case AT_TELL_ON_ROAD:

cout << "on road ---> on road" << endl;

break;

case AT_TELL_IN_RIVER:

cout << "on road ---> in river" << endl;

soldier->ChangeScenario(CInRiver::Instance());

break;

case AT_TELL_MEET_ENEMY:

cout << "on road ---> meets enymy" << endl;

soldier->ChangeScenario(CMeetEnemy::Instance());

break;

case AT_WALK:

cout << "on road : walk now" << endl;

break;

default:

cout << "unkown action type" << endl;

break;

}

return;

}

// 2.实现CInRiver

CScenario * CInRiver::_instance = NULL;

CScenario * CInRiver::Instance()

{

if (_instance == NULL)

{

_instance = new CInRiver();

}

return _instance;

}

void CInRiver::Swim()

{

cout << "swim" << endl;

return;

}

int CInRiver::GetSupportedAction()

{

return AT_TELL_INFO | AT_SWIM;

}

void CInRiver::ChangeScenario(CSoldier * soldier,CScenario * scenario)

{

soldier->ChangeScenario(scenario);

return;

}

void CInRiver::act(CSoldier * soldier,ActionType at)

{

switch(at)

{

case AT_TELL_ON_ROAD:

cout << "in river ---> on road" << endl;

soldier->ChangeScenario(COnRoad::Instance());

break;

case AT_TELL_IN_RIVER:

cout << "in river ---> in river" << endl;

break;

case AT_TELL_MEET_ENEMY:

cout << "in river : meets enymy" << endl;

soldier->ChangeScenario(CMeetEnemy::Instance());

break;

case AT_SWIM:

cout << "in river : swim now" << endl;

break;

default:

cout << "unkown action type" << endl;

break;

}

return;

}

// 3.实现CMeetEnemy

CScenario * CMeetEnemy::_instance = NULL;

CScenario * CMeetEnemy::Instance()

{

if (_instance == NULL)

{

_instance = new CMeetEnemy();

}

return _instance;

}

void CMeetEnemy::Fire()

{

cout << "fire" << endl;

return;

}

int CMeetEnemy::GetSupportedAction()

{

return AT_TELL_INFO | AT_FIRE;

}

void CMeetEnemy::ChangeScenario(CSoldier * soldier,CScenario * scenario)

{

soldier->ChangeScenario(scenario);

return;

}

void CMeetEnemy::act(CSoldier * soldier,ActionType at)

{

switch(at)

{

case AT_TELL_ON_ROAD:

cout << "meet enemy ---> on road" << endl;

soldier->ChangeScenario(COnRoad::Instance());

break;

case AT_TELL_IN_RIVER:

cout << "meet enemy ---> in river" << endl;

soldier->ChangeScenario(CInRiver::Instance());

break;

case AT_TELL_MEET_ENEMY:

cout << "meet enemy ---> meet enymy" << endl;

break;

case AT_FIRE:

cout << "meet enemy : fire now" << endl;

break;

default:

cout << "unkown action type" << endl;

break;

}

return;

}

//StatePatternTest.cpp

// StateMachine.cpp : Defines the entry point for the console application.

#include < windows.h >

#include " StatePattern.h "

int main( int argc, char * argv[])

{

typedef CScenario::ActionType ActionType;

ActionType at;

CSoldier soldier;

//0.在陆地上

at = CScenario::AT_TELL_ON_ROAD;