c++设计模式之状态模式

一. 状态模式

定义：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。

实现方式1：

workstate 状态抽象类

workstate1 状态实现类1

workstate2 状态实现类2

workstate3 状态实现类3

workstate4 状态实现类4

workoperation 任务执行类

这种状态模式是比较简单的状态模式，通过任务执行类改变状态的走向，代码如下

class workstate
{
    virtual void operation() = 0;
};

class workstate1
{
    virtual void operation() 
    {
        cout<<"Do WorkState1"<<endl;
    }
};


class workstate2
{
    virtual void operation() 
    {
        cout<<"Do WorkState2"<<endl;
    }
};


class workstate3
{
    virtual void operation() 
    {
        cout<<"Do WorkState3"<<endl;
    }
};

class workstate4
{
    virtual void operation() 
    {
        cout<<"Do WorkState4"<<endl;
    }
};

class workoperation{
    workoperation(int state);
    
private:
    int m_state;
    void doOperation()
    {
        switch(m_state)
        {
        case 1:workstate *pstate = new workstate1();pstate->operation();m_state = 2;break;
        case 2:workstate *pstate = new workstate2();pstate->operation();m_state = 3;break;
        case 3:workstate *pstate = new workstate3();pstate->operation();m_state = 4;break;
        case 4:workstate *pstate = new workstate4();pstate->operation();m_state = 1;break;
        }
    }
    void setstate(int g_state)
    {
        m_state = g_state;
    }
    int getstate()
    {
        return m_state;
    }
};

实现方式2：

workstate 状态抽象类

workstate1 状态实现类1

workstate2 状态实现类2

workstate3 状态实现类3

workstate4 状态实现类4

workoperation 任务执行类

这种状态模式，通过状态实现类实现任务执行类的状态变化，代码如下

class workoperation;
class workstate1;
class workstate2;
class workstate3;
class workstate4;

static workstate1 m_workstate1;
static workstate2 m_workstate2;
static workstate3 m_workstate3;
static workstate4 m_workstate4;


class workstate
{
    virtual void operation() = 0;
    workoperation *m_workoperation;
};

class workstate1:public workstate
{
    workstate1(workoperation *g_workoperation)
    {
            m_workoperation =  g_workoperation;
    }
    virtual void operation() 
    {
        cout<<"Do WorkState1"<<endl;
        m_workoperation::m_workstate = &m_workstate2
        m_workoperation->m_state(2);
    }
};


class workstate2:public workstate
{
    workstate2(workoperation *g_workoperation)
    {
        m_workoperation =  g_workoperation;
    }
    virtual void operation() 
    {
        cout<<"Do WorkState2"<<endl;
        m_workoperation::m_workstate = &m_workstate3
        m_workoperation->m_state(3);
    }
};


class workstate3:public workstate
{
    workstate3(workoperation *g_workoperation)
    {
        m_workoperation =  g_workoperation;
    }
    virtual void operation() 
    {
        cout<<"Do WorkState3"<<endl;
        m_workoperation::m_workstate = &m_workstate4
        m_workoperation->m_state(4);
    }
};

class workstate4:public workstate
{
    workstate4(workoperation *g_workoperation)
    {
        m_workoperation =  g_workoperation;
    }
    virtual void operation() 
    {
        cout<<"Do WorkState4"<<endl;
        m_workoperation::m_workstate = &m_workstate1
        m_workoperation->m_state(1);
    }
};


class workoperation{
    workoperation(workstate *pstate)
    {
        m_workstate = pstate;
    }
    
private:
    workstate *m_workstate;
    int m_state;
    void doOperation()
    {
        m_workstate->operation();
    }
    void setstate(int g_state)
    {
        m_state = g_state;
    }
    int getstate()
    {
        return m_state;
    }
};