设计模式C++学习笔记之十九（State状态模式）

Admin

19.1.解释

概念：允许一个对象在其内部状态改变时改变它的行为。对象看起来似乎修改了它的类。

main()，客户

CLiftState，电梯状态抽象类

CCloseingState，电梯门关闭

COpenningState，电梯门打开

CRunningState，电梯运行

CStoppingState，电梯停止

CContext，电梯的控制面板

说明：CContext保持电梯的状态，并提供操作的接口函数。当函数被调用时，CContext直接调用当前状态的相应函数。由状态的接口函数来确定是否可以执行这个动作，以及修改状态为执行这个动作后的状态。

看代码：第一块是不使用模式的做法，第二块是使用模式的做法，在main()函数里会有调用的方式。

[mw_shl_code=cpp,true]//ILift.h
#pragma once
class ILift
{
public:

    ILift(void)
    {
    }

    virtual ~ILift(void)
    {
    }
    static const int OPENING_STATE = 1;
    static const int CLOSING_STATE = 2;
    static const int RUNNING_STATE = 3;
    static const int STOPPING_STATE = 4;
    virtual void SetState(int state) = 0;
    virtual void Open() = 0;
    virtual void Close() = 0;
    virtual void Run() = 0;
    virtual void Stop() = 0;
};[/mw_shl_code]

[mw_shl_code=cpp,true]//Lift.h
#pragma once
#include "ilift.h"
class CLift :
    public ILift
{
public:
    CLift(void);
    ~CLift(void);
    void SetState(int state);
    void Open();
    void Close();
    void Run();
    void Stop();
private:
    int m_state;
    void OpenWithoutLogic();
    void CloseWithoutLogic();
    void RunWithoutLogic();
    void StopWithoutLogic();
};[/mw_shl_code]

[mw_shl_code=cpp,true]//Lift.cpp
#include "StdAfx.h"
#include "Lift.h"
#include <iostream>
using std::cout;
using std::endl;

CLift::CLift(void)
{
    this->m_state = 0;
}

CLift::~CLift(void)
{
}

void CLift::SetState(int state)
{
    this->m_state = state;
}

void CLift::Open()
{
    switch(this->m_state)
    {
    case OPENING_STATE:
        break;
    case CLOSING_STATE:
        this->OpenWithoutLogic();
        this->SetState(OPENING_STATE);
        break;
    case RUNNING_STATE:
        break;
    case STOPPING_STATE:
        this->OpenWithoutLogic();
        this->SetState(OPENING_STATE);
        break;
    }
}

void CLift::Close()
{
    switch(this->m_state)
    {
    case OPENING_STATE:
        this->CloseWithoutLogic();
        this->SetState(CLOSING_STATE);
        break;
    case CLOSING_STATE:
        break;
    case RUNNING_STATE:
        break;
    case STOPPING_STATE:
        break;
    }
}

void CLift::Run()
{
    switch(this->m_state)
    {
    case OPENING_STATE:
        break;
    case CLOSING_STATE:
        this->RunWithoutLogic();
        this->SetState(RUNNING_STATE);
        break;
    case RUNNING_STATE:
        break;
    case STOPPING_STATE:
        this->RunWithoutLogic();
        this->SetState(RUNNING_STATE);
        break;
    }
}

void CLift::Stop()
{
    switch(this->m_state)
    {
    case OPENING_STATE:
        break;
    case CLOSING_STATE:
        this->StopWithoutLogic();
        this->SetState(CLOSING_STATE);
        break;
    case RUNNING_STATE:
        this->StopWithoutLogic();
        this->SetState(CLOSING_STATE);
        break;
    case STOPPING_STATE:
        break;
    }
}

void CLift::OpenWithoutLogic()
{
    cout << "电梯门开启..." << endl;
}

void CLift::CloseWithoutLogic()
{
    cout << "电梯门关闭..." << endl;
}

void CLift::RunWithoutLogic()
{
    cout << "电梯上下跑起来..." << endl;
}

void CLift::StopWithoutLogic()
{
    cout << "电梯停止了..." << endl;
}[/mw_shl_code]
[mw_shl_code=cpp,true]//LiftState.h
#pragma once
class CContext;
class CLiftState
{
public:
    CLiftState(void);
    virtual ~CLiftState(void);
    void SetContext(CContext *pContext);
    virtual void Open() = 0;
    virtual void Close() = 0;
    virtual void Run() = 0;
    virtual void Stop() = 0;
protected:
    CContext *m_pContext;
};[/mw_shl_code]

[mw_shl_code=cpp,true]//LiftState.cpp
#include "StdAfx.h"
#include "LiftState.h"

CLiftState::CLiftState(void)
{
}

CLiftState::~CLiftState(void)
{
}

void CLiftState::SetContext( CContext *pContext )
{
    m_pContext = pContext;
}
[/mw_shl_code]
[mw_shl_code=cpp,true]//CloseingState.h
#pragma once
#include "liftstate.h"
class CCloseingState :
    public CLiftState
{
public:
    CCloseingState(void);
    ~CCloseingState(void);
    void Open();
    void Close();
    void Run();
    void Stop();
};
[/mw_shl_code]
[mw_shl_code=cpp,true]//CloseingState.cpp
#include "StdAfx.h"
#include "CloseingState.h"
#include "Context.h"
#include <iostream>
using std::cout;
using std::endl;

CCloseingState::CCloseingState(void)
{
}

CCloseingState::~CCloseingState(void)
{
}

void CCloseingState::Open()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pOpenningState);
    this->CLiftState::m_pContext->GetLiftState()->Open();
}

void CCloseingState::Close()
{
    cout << "电梯门关闭..." << endl;
}

void CCloseingState::Run()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pRunningState);
    this->CLiftState::m_pContext->GetLiftState()->Run();
}

void CCloseingState::Stop()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pStoppingState);
    this->CLiftState::m_pContext->GetLiftState()->Stop();
}[/mw_shl_code]

[mw_shl_code=cpp,true]//OpenningState.h
#pragma once
#include "liftstate.h"
class COpenningState :
    public CLiftState
{
public:
    COpenningState(void);
    ~COpenningState(void);
    void Open();
    void Close();
    void Run();
    void Stop();
};[/mw_shl_code]

[mw_shl_code=cpp,true]//OpenningState.cpp
#include "StdAfx.h"
#include "OpenningState.h"
#include "Context.h"
#include <iostream>
using std::cout;
using std::endl;

COpenningState::COpenningState(void)
{
}

COpenningState::~COpenningState(void)
{
}

void COpenningState::Open()
{
    cout << "电梯门开启..." << endl;
}

void COpenningState::Close()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pCloseingState);
    this->CLiftState::m_pContext->GetLiftState()->Close();
}

void COpenningState::Run()
{
    //do nothing
}

void COpenningState::Stop()
{
    //do nothing
}
[/mw_shl_code]
[mw_shl_code=cpp,true]//RunningState.h
#pragma once
#include "liftstate.h"
class CRunningState :
    public CLiftState
{
public:
    CRunningState(void);
    ~CRunningState(void);
    void Open();
    void Close();
    void Run();
    void Stop();
};[/mw_shl_code]

[mw_shl_code=cpp,true]//RunningState.cpp
#include "StdAfx.h"
#include "RunningState.h"
#include "Context.h"
#include <iostream>
using std::cout;
using std::endl;

CRunningState::CRunningState(void)
{
}

CRunningState::~CRunningState(void)
{
}

void CRunningState::Open()
{
    //do nothing
}

void CRunningState::Close()
{
    //do nothing
}

void CRunningState::Run()
{
    cout << "电梯上下跑..." << endl;
}

void CRunningState::Stop()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pStoppingState);
    this->CLiftState::m_pContext->GetLiftState()->Stop();
}
[/mw_shl_code]
[mw_shl_code=cpp,true]//StoppingState.h
#pragma once
#include "liftstate.h"
class CStoppingState :
    public CLiftState
{
public:
    CStoppingState(void);
    ~CStoppingState(void);
    void Open();
    void Close();
    void Run();
    void Stop();
};[/mw_shl_code]

[mw_shl_code=cpp,true]//StoppingState.cpp
#include "StdAfx.h"
#include "StoppingState.h"
#include "Context.h"
#include <iostream>
using std::cout;
using std::endl;

CStoppingState::CStoppingState(void)
{
}

CStoppingState::~CStoppingState(void)
{
}

void CStoppingState::Open()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pOpenningState);
    this->CLiftState::m_pContext->GetLiftState()->Open();
}

void CStoppingState::Close()
{
    //do nothing
}

void CStoppingState::Run()
{
    this->CLiftState::m_pContext->SetLiftState(CContext::pRunningState);
    this->CLiftState::m_pContext->GetLiftState()->Run();
}

void CStoppingState::Stop()
{
    cout << "电梯停止了..." << endl;
}[/mw_shl_code]
[mw_shl_code=cpp,true]//Contex.h
#pragma once
#include "LiftState.h"
#include "OpenningState.h"
#include "CloseingState.h"
#include "RunningState.h"
#include "StoppingState.h"
class CContext
{
public:
    CContext(void);
    ~CContext(void);
    static COpenningState *pOpenningState;
    static CCloseingState *pCloseingState;
    static CRunningState *pRunningState;
    static CStoppingState *pStoppingState;
    CLiftState * GetLiftState();
    void SetLiftState(CLiftState *pLiftState);
    void Open();
    void Close();
    void Run();
    void Stop();
private:
    CLiftState *m_pLiftState;
};[/mw_shl_code]

[mw_shl_code=cpp,true]//Context.cpp
#include "StdAfx.h"
#include "Context.h"
COpenningState* CContext::pOpenningState = NULL;
CCloseingState* CContext::pCloseingState = NULL;
CRunningState* CContext::pRunningState = NULL;
CStoppingState* CContext::pStoppingState = NULL;

CContext::CContext(void)
{
    m_pLiftState = NULL;
    pOpenningState = new COpenningState();
    pCloseingState = new CCloseingState();
    pRunningState = new CRunningState();
    pStoppingState = new CStoppingState();
}

CContext::~CContext(void)
{
    delete pOpenningState;
    pOpenningState = NULL;
    delete pCloseingState;
    pCloseingState = NULL;
    delete pRunningState;
    pRunningState = NULL;
    delete pStoppingState;
    pStoppingState = NULL;
}

CLiftState * CContext::GetLiftState()
{
    return m_pLiftState;
}

void CContext::SetLiftState(CLiftState *pLiftState)
{
    this->m_pLiftState = pLiftState;
    this->m_pLiftState->SetContext(this);
}

void CContext::Open()
{
    this->m_pLiftState->Open();
}

void CContext::Close()
{
    this->m_pLiftState->Close();
}

void CContext::Run()
{
    this->m_pLiftState->Run();
}

void CContext::Stop()
{
    this->m_pLiftState->Stop();
}
[/mw_shl_code]
[mw_shl_code=cpp,true]// State.cpp : 定义控制台应用程序的入口点。
#include "stdafx.h"
#include "ILift.h"
#include "Lift.h"
#include "Context.h"
#include "OpenningState.h"
#include "CloseingState.h"
#include "RunningState.h"
#include "StoppingState.h"
#include <iostream>
using std::cout;
using std::endl;

void DoIt()
{
    //ILift.h, Lift.h, Lift.cpp
    ILift *pLift = new CLift();
    pLift->SetState(ILift::STOPPING_STATE);//电梯的初始条件是停止状态。
    pLift->Open();//首先是电梯门开启，人进去
    pLift->Close();//然后电梯门关闭
    pLift->Run();//再然后，电梯跑起来，向上或者向下
    pLift->Stop();//最后到达目的地，电梯停下来
    delete pLift;
}


void DoNew()
{
    //LiftState.h, LiftState.cpp, OpenningState.h, CloseingState.h, RunningState.h, StoppingState.h
    //Context.h, Context.cpp
    CContext context;
    CCloseingState closeingState;
    context.SetLiftState(&closeingState);
    context.Close();
    context.Open();
    context.Run();
    context.Stop();
}

int _tmain(int argc, _TCHAR* argv[])
{
    cout << "----------使用模式之前----------" << endl;
    DoIt();
    cout << "----------使用模式之后----------" << endl;
    DoNew();

    _CrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF | _CRTDBG_ALLOC_MEM_DF);
    _CrtDumpMemoryLeaks();
    return 0;
}[/mw_shl_code]

状态模式也是行为型模式。写了好多天了，才发现如何在页面上插入代码。这样方便多了，看起来也清楚多了。博客园也许需要开个入门贴子，免得新来博客园的童鞋都不大会用。这几天还在学习数据结构中的排序，入排序入手来学习数据结构还是比较容易的。上学的时候只顾着考试了，该学的也都学了，但考完试就全忘掉，已经成为了一种习惯。现在再补回来。鼓励自己加油！一定要做一个学习型的程序员。

夜行的猫仔

在游戏中经常使用的状态机（状态机制）就是这种思维模式。
比如，玩家有走路动作和攻击动作，这两个动作都需要有一定的持续时间。
假如我们不使用状态机，而是及时响应，那么点击键盘行走的时候迈出左腿，当我们抬起按键角色停在原地。这样看起来和合理。但在实际开发的时候就会发现，我们按住键盘不停，那么始终有个指令发送行走，角色就会不停地迈出左腿。如果使用状态机，只要是行走状态就播放行走动画，而且按键只负责将状态改为行走状态。这样的话行走看起来就很流畅了。