前提：因?yàn)樽罱蛩銓W(xué)設(shè)計(jì)模式的狀態(tài)模式，但不是很明白有限狀態(tài)機(jī)和狀態(tài)模式之間的關(guān)系，索性用C++實(shí)現(xiàn)了一個(gè)簡(jiǎn)單案例復(fù)習(xí)了一下FSM，如果有更好的實(shí)現(xiàn)方法，歡迎留言

有限狀態(tài)機(jī)四大要素

現(xiàn)態(tài)：當(dāng)前所處狀態(tài)
次態(tài)：當(dāng)條件滿足后，即將轉(zhuǎn)移的下一個(gè)狀態(tài)
動(dòng)作：當(dāng)滿足某個(gè)事件時(shí)執(zhí)行的動(dòng)作；動(dòng)作執(zhí)行完畢后可以轉(zhuǎn)移到另一個(gè)狀態(tài)或保持原有狀態(tài)
條件：轉(zhuǎn)移狀態(tài)所需的條件，當(dāng)滿足條件時(shí)，會(huì)觸發(fā)一個(gè)動(dòng)作或進(jìn)行狀態(tài)轉(zhuǎn)移

C++函數(shù)指針實(shí)現(xiàn)

案例：學(xué)生的日常生活。

學(xué)生的日常生活包含以下幾個(gè)狀態(tài)：起床、上學(xué)、吃午飯、做作業(yè)、睡覺(jué)；
每個(gè)狀態(tài)之間進(jìn)行轉(zhuǎn)移需要執(zhí)行相應(yīng)的事件。

我分為以下幾個(gè)步驟來(lái)實(shí)現(xiàn)：

（1）繪制狀態(tài)轉(zhuǎn)移圖
（2）創(chuàng)建狀態(tài)轉(zhuǎn)移的FSMItem類
- 枚舉：所有狀態(tài)State、所有事件Event；
- 成員變量：現(xiàn)態(tài)_curState、事件_event、次態(tài)_nextState
- 成員函數(shù)：動(dòng)作函數(shù)
（3）創(chuàng)建有限狀態(tài)機(jī)FSM類
- 成員變量：狀態(tài)轉(zhuǎn)移表vector<FSMItem*> _fsmTable
- 成員函數(shù)：初始化狀態(tài)轉(zhuǎn)移表、狀態(tài)轉(zhuǎn)移、根據(jù)事件執(zhí)行相應(yīng)動(dòng)作
（4）測(cè)試FSM

（1）繪制狀態(tài)轉(zhuǎn)移圖

在這里插入圖片描述

（2）FSMItem類

//FSM狀態(tài)項(xiàng)
class FSMItem
{
    friend class FSM;
private:
   	//動(dòng)作函數(shù)
    static void getUp()
    {
        cout << "student is getting up!" << endl;
    }
    static void go2School()
    {
        cout << "student is going to school!" << endl;
    }
    static void haveLunch()
    {
        cout << "student is having lunch!" << endl;
    }
    static void doHomework()
    {
        cout << "student is doing homework!" << endl;
    }
    static void sleeping()
    {
        cout << "student is sleeping!" << endl;
    }
public:
    //枚舉所有狀態(tài)
    enum State
    {
        GETUP = 0,
        GOTOSCHOOL,
        HAVELUNCH,
        DOHOMEWORK,
        SLEEP
    };
    //枚舉所有事件
    enum Events
    {
        EVENT1 = 0,
        EVENT2,
        EVENT3
    };
public:
    //初始化構(gòu)造函數(shù)
    FSMItem(State curState, Events event, void(*action)(), State nextState)
        :_curState(curState), _event(event), _action(action), _nextState(nextState) {}
private:
    State   _curState;      //現(xiàn)態(tài)
    Events  _event;         //條件
    void    (*_action)();   //動(dòng)作
    State   _nextState;     //次態(tài)
};

（3）FSM類

class FSM
{
public:
    //初始化狀態(tài)機(jī)
    FSM(FSMItem::State curState= FSMItem::GETUP):_curState(curState)
    {
        initFSMTable();
    }
    //狀態(tài)轉(zhuǎn)移
    void transferState(FSMItem::State nextState)
    {
        _curState = nextState;
    }
    //根據(jù)當(dāng)前狀態(tài)和發(fā)生的事件，執(zhí)行相應(yīng)的動(dòng)作，并進(jìn)行狀態(tài)轉(zhuǎn)移
    void handleEvent(FSMItem::Events event)
    {
        FSMItem::State  curState = _curState;   //現(xiàn)態(tài)
        void (*action)() = nullptr;//動(dòng)作
        FSMItem::State nextState;  //次態(tài)
        bool flag = false;
        for (int i = 0; i < _fsmTable.size(); i++)
        {
            if (event == _fsmTable[i]->_event && curState == _fsmTable[i]->_curState)
            {
                flag = true;
                action = _fsmTable[i]->_action;
                nextState = _fsmTable[i]->_nextState;
                break;
            }
        }
        //找到對(duì)應(yīng)的狀態(tài)項(xiàng)，執(zhí)行動(dòng)作，轉(zhuǎn)移狀態(tài)
        if (flag)
        {
            if (action)
            {
                action();
            }
            transferState(nextState);
        }
    }
private:
    //根據(jù)畫(huà)的狀態(tài)轉(zhuǎn)移圖初始化狀態(tài)轉(zhuǎn)移表
    void initFSMTable()
    {
        _fsmTable.push_back(new FSMItem(FSMItem::GETUP, FSMItem::EVENT1, &FSMItem::getUp, FSMItem::GOTOSCHOOL));
        _fsmTable.push_back(new FSMItem(FSMItem::GOTOSCHOOL, FSMItem::EVENT2, &FSMItem::go2School, FSMItem::HAVELUNCH));
        _fsmTable.push_back(new FSMItem(FSMItem::HAVELUNCH, FSMItem::EVENT3, &FSMItem::haveLunch, FSMItem::DOHOMEWORK));
        _fsmTable.push_back(new FSMItem(FSMItem::DOHOMEWORK, FSMItem::EVENT1, &FSMItem::doHomework, FSMItem::SLEEP));
        _fsmTable.push_back(new FSMItem(FSMItem::SLEEP, FSMItem::EVENT2, &FSMItem::sleeping, FSMItem::GETUP));
    }
public:
    FSMItem::State _curState;  //現(xiàn)態(tài)
private:
    vector<FSMItem*> _fsmTable;  //狀態(tài)轉(zhuǎn)移表
};

（4）測(cè)試FSM

#include<iostream>
#include<vector>
using namespace std;
//測(cè)試事件變換
void testEvent(FSMItem::Events& event)
{
    switch (event)
    {
    case FSMItem::EVENT1:
        event = FSMItem::EVENT2;
        break;
    case FSMItem::EVENT2:
        event = FSMItem::EVENT3;
        break;
    case FSMItem::EVENT3:
        event = FSMItem::EVENT1;
        break;
    }
}
int main()
{
    FSM *fsm = new FSM();
    auto event = FSMItem::EVENT1;
    while (1)
    {
        cout << "event " << event << " is coming..." << endl;
        fsm->handleEvent(event);
        cout << "fsm current state is " << fsm->_curState << endl;
        testEvent(event);
    }
    return 0;
}

執(zhí)行效果：

在這里插入圖片描述