设计模式01-状态模式

　　设计模式概念接触到比较早，之前看看感觉各个模式讲的都差不多，可能感悟不深。最近研究一下，通过具体代码示例加深理解。

　　今天学习的是状态模式。状态模式主要的精髓在于把各种状态抽象出来，每种状态的业务逻辑在各自的状态中去实现。把整体的业务逻辑抽象成一个具体调用各状态的类。整体的业务逻辑，即是在各状态类之间进行切换，调用。

　　下面以自动售货机为例，说明状态模式。自动售货机为一个整体的业务逻辑对象，自动售货机可能有以下几种状态：

1.未投币

2.已投币

3.准备出货

4.售罄

自动售货机对象可能有以下几个动作：

1.投币

2.退币

3.按出货按钮

4.出货

类图如下：

代码如下：

自动售货机类：vendingMachin.h

/************************************************************************/
/* 
    自动售货机类.
*/
/************************************************************************/

#ifndef        __VENDINGMACHIN_H__
#define        __VENDINGMACHIN_H__

#include "hasMoneyState.h"
#include "noMoney.h"
#include "soldOut.h"
#include "soldState.h"

class VendingMachin
{
public:
    VendingMachin(int count);
    void    putMoney();
    void    backMoney();
    void    pressButton();
    void    outGoods();

    void    setState(MachineState* pstate);
    int        getCount();
    MachineState * getNoMoneyState();
    MachineState * getHasMoneyState();
    MachineState * getSoldState();
    MachineState * getSoldOutState();
private:
    int                m_count;
    MachineState*    m_phasMoney;
    MachineState*    m_pnoMoney;
    MachineState*    m_psold;
    MachineState*    m_psoldOut;
    MachineState*    m_pcurrent;
};

#endif

vendingMachin.cpp

#include "vendingMachin.h"

VendingMachin::VendingMachin(int count)
{

    m_phasMoney = new HasMoneyState(this);
    m_psoldOut = new SoldOut(this);
    m_psold = new SoldState(this);
    m_pnoMoney = new NoMoney(this);
    
    
    if (count > 0)
    {
        m_count = count;
        setState(m_pnoMoney);
    }
}

int VendingMachin::getCount()
{
    return m_count;
}

void VendingMachin::setState(MachineState* pstate)
{
    m_pcurrent = pstate;
}

void VendingMachin::putMoney()
{
    m_pcurrent->putMoney();
}

void VendingMachin::backMoney()
{
    m_pcurrent->backMoney();
}

void VendingMachin::pressButton()
{
    m_pcurrent->pressButton();

    // 如果当前状态为准备出货状态，则按下出货按钮，进行出货
    if (m_pcurrent->getState() == eSOLDING)
    {
        m_pcurrent->outGoods();
    }
}

void VendingMachin::outGoods()
{
    //m_pcurrent->outGoods();
    if (m_count > 0)
    {
        m_count--;
        printf("售出一件商品
");
    }
}

MachineState* VendingMachin::getHasMoneyState()
{
    return m_phasMoney;
}

MachineState* VendingMachin::getNoMoneyState()
{
    return m_pnoMoney;
}

MachineState* VendingMachin::getSoldOutState()
{
    return m_psoldOut;
}

MachineState* VendingMachin::getSoldState()
{
    return m_psold;
}

状态基类：MachineState.h

#ifndef __MACHINESTATE_H__
#define __MACHINESTATE_H__

#include <stdio.h>

/************************************************************************/
/*     
    模拟自动售货机状态基类
    对应四种状态 ：已投币，未投币，出货，售罄
*/
/************************************************************************/

class VendingMachin;

enum VendingState{eNOMONEY,eHASMONEY,eSOLDOUT,eSOLDING};

class  MachineState
{
public:

    virtual ~MachineState(){}

    // 投钱
    virtual        void    putMoney() = 0;

    // 退钱
    virtual        void    backMoney() = 0;

    // 出货
    virtual        void    outGoods() = 0;  

    // 点击出货按钮
    virtual        void    pressButton() = 0;

    // 获取当前状态
    virtual        VendingState    getState() = 0;

};

#endif

以下是四种状态类：

未投币状态类：noMoney.h

/************************************************************************/
/* 
    未投币状态
*/
/************************************************************************/

#ifndef        __NOMONEY_H__
#define        __NOMONEY_H__

#include "machineState.h"

class  NoMoney :public MachineState
{
public:
    NoMoney(VendingMachin* vm);
    virtual ~NoMoney();

    void    putMoney();
    void    backMoney();
    void    pressButton();
    void    outGoods();
    VendingState getState();

protected:
    VendingMachin*        m_pVm;
};

#endif

noMoney.cpp

#include "noMoney.h"
#include "vendingMachin.h"

NoMoney::NoMoney(VendingMachin* vm)
{
    m_pVm = vm;
}

NoMoney::~NoMoney()
{

}

void NoMoney::putMoney()
{
    printf("投币成功!
");

    // 状态设置为已投币
    m_pVm->setState(m_pVm->getHasMoneyState());
}

void NoMoney::backMoney()
{
    printf("您未投币，想退钱？...
");
}

void NoMoney::pressButton()
{
    printf("您未投币，想拿东西么？...
");
}

void NoMoney::outGoods()
{
    printf("非法状态
");
}

VendingState NoMoney::getState()
{
    return eNOMONEY;
}

已投币状态：hasMoneyState.h

#include "machineState.h"

#ifndef        __HASMONEYSTATE_H__
#define        __HASMONEYSTATE_H__


class HasMoneyState :public MachineState
{
public:
    HasMoneyState(VendingMachin*vm);
    virtual ~HasMoneyState();

    void    putMoney();
    void    backMoney();
    void    pressButton();
    void    outGoods();
    VendingState    getState();
protected:
    VendingMachin*        m_pVm;

};

#endif




#include "hasMoneyState.h"
#include "vendingMachin.h"

HasMoneyState::HasMoneyState(VendingMachin*vm)
{
    m_pVm = vm;
}

HasMoneyState::~HasMoneyState()
{

}

void HasMoneyState::putMoney()
{
    printf("您已经投过币了，无需再投
");
}

void HasMoneyState::backMoney()
{
    printf("退币成功
");

    // 状态改为未投币
    m_pVm->setState(m_pVm->getNoMoneyState());
}

void HasMoneyState::pressButton()
{
    printf("您按下了取货按钮
");

    // 状态设置为待出货状态
    m_pVm->setState(m_pVm->getSoldState());
}

void HasMoneyState::outGoods()
{
    printf("非法状态
");
}

VendingState HasMoneyState::getState()
{
    return eHASMONEY;
}

准备出货状态：soldState

/************************************************************************/
/* 
    出货状态
*/
/************************************************************************/

#ifndef        __SOLDSTATE_H__
#define        __SOLDSTATE_H__

#include "machineState.h"

class SoldState :public MachineState
{
public:
    SoldState(VendingMachin* vm);
    virtual ~SoldState();

    void    putMoney();
    void    backMoney();
    void    pressButton();
    void    outGoods();
    VendingState getState();
protected:
    VendingMachin*        m_pVm;
};

#endif

#include "soldState.h"
#include "vendingMachin.h"

SoldState::SoldState(VendingMachin* vm)
{
    m_pVm = vm;
}

SoldState::~SoldState()
{

}

void SoldState::putMoney()
{
    printf("正在出货，请勿投币
");
}

void SoldState::backMoney()
{
    printf("正在出货，没有可退的钱
");
}

void SoldState::pressButton()
{
    printf("正在出货，请勿重复转动手柄
");
}

void SoldState::outGoods()
{
    m_pVm->outGoods();
    if (m_pVm->getCount() >0 )
    {
        m_pVm->setState(m_pVm->getNoMoneyState());
    }
    else
    {
        printf("商品已经售罄
");
        m_pVm->setState(m_pVm->getSoldOutState());
    }

}

VendingState SoldState::getState()
{
    return eSOLDING;
}

售罄状态：soldOut

/************************************************************************/
/* 
    售罄状态
*/
/************************************************************************/

#ifndef        __SOLDOUT_H__
#define        __SOLDOUT_H__

#include "machineState.h"

class SoldOut :public MachineState
{
public:
    SoldOut(VendingMachin* vm);
    virtual ~SoldOut();

    void    putMoney();
    void    backMoney();
    void    pressButton();
    void    outGoods();
    VendingState getState();
protected:
    VendingMachin*        m_pVm;
};

#endif

#include "soldOut.h"
#include "vendingMachin.h"

SoldOut::SoldOut(VendingMachin* vm)
{
    m_pVm = vm;
}

SoldOut::~SoldOut()
{

}

void SoldOut::putMoney()
{
    printf("投币失败，商品已售罄
");
}

void SoldOut::backMoney()
{
    printf("您未投币，想退钱么？...
");
}

void SoldOut::pressButton()
{
    printf("商品售罄，请勿按动按钮
");
}

void SoldOut::outGoods()
{
    printf("非法状态
");
}

VendingState SoldOut::getState()
{
    return eSOLDOUT;
}

测试代码：

// State.cpp : 定义控制台应用程序的入口点。
//
#include "vendingMachin.h"

int main(int argc, char* argv[])
{
    VendingMachin *vm = new VendingMachin(10);
    
    vm->putMoney();
    vm->backMoney();
    vm->pressButton();
    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();
    vm->putMoney();
    vm->pressButton();
    vm->putMoney();
    vm->pressButton();
    vm->putMoney();
    vm->pressButton();
    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();

    vm->putMoney();
    vm->pressButton();

    return 0;
}