c++ 状态模式（state）

/************************************************************************/
/*                         状态模式                                     */
/************************************************************************/
#include <iostream>

using namespace std;

/*
    一个状态接口，不同的状态从该接口中继承出来，想要增加新的状态
    时，只需从此接口中派生出新的类即可，适合于当判断较多(多个状态切换频繁)的场合

    这里引入一个程序员写工程程序的例子，程序员在一天的不同时间会处于不同的状态
    如果程序写不完还得加班,即程序员的状态会随着时间发生改变
*/
class Work;

/*状态接口State*/
class State
{
public:
    virtual void WriteProgram(Work *w) = ;//写程序的行为(与Work相关的行为)
};

//工作类
class Work
{
private:
    State *current;//当前状态
    double hour;
    bool taskFinish;

public:
    Work()
    {
        taskFinish = false;
    }

    void SetTime(double hour)
    {
        this->hour = hour;
    }

    double GetTime()
    {
        return this->hour;
    }

    //设置状态
    void SetState(State *s)
    {
        current = s;
    }

    //设置工程是否完成
    void SetFinish()
    {
        taskFinish = true;
    }

    bool GetFinish()
    {
        return taskFinish;
    }

    void WriteProgram()
    {
        current->WriteProgram(this);
    }

};

//下班休息状态
class RestState : public State
{
public:
    void WriteProgram(Work *w)
    {
        cout<<"当前时间:"<<w->GetTime()<<"点 工作完成，下班回家了"<<endl;
    }

};

//睡眠工作状态
class SleepingState : public State
{
public:
    void WriteProgram(Work *w)
    {
        cout<<"受不了了,"<<w->GetTime()<<"点了，先睡吧"<<endl;
    }

};

//晚上工作状态
class EveningState : public State
{
public:
    void WriteProgram(Work *w)
    {
        //任务完成了，可以休息了
        if(w->GetFinish())
        {
            w->SetState(new RestState());
            w->WriteProgram();
        }else
        {
            if(w->GetTime()<){
                cout<<"当前时间:"<<w->GetTime()<<"点 加班了，疲惫至极"<<endl;
            }else
            {
                //找过21点
                w->SetState(new SleepingState());
                w->WriteProgram();
            }
        }
    }

};

//下午工作状态
class AfternoonState : public State
{

public:
    void WriteProgram(Work *w)
    {
        if(w->GetTime()<)
        {
            cout<<"当前时间:"<<w->GetTime()<<"点 状态还不错，继续努力"<<endl;
        }else
        {
            w->SetState(new EveningState());
            w->WriteProgram();
        }
    }
};

//中午工作状态
class NoonState : public State
{
public:
    void WriteProgram(Work *w)
    {
        if (w->GetTime()<)
            cout<<"当前时间:"<<w->GetTime()<<"点 饿了，午饭:犯困，午休"<<endl;
        else
        {
            w->SetState(new AfternoonState());
            w->WriteProgram();
        }
    }

};

//上午工作状态
class ForenoonState : public State
{
public:
    void WriteProgram(Work *w)
    {
        if(w->GetTime()<)
            cout<<"当前时间:"<<w->GetTime()<<"点 上午工作，精神百倍"<<endl;
        else
        {
            w->SetState(new NoonState());
            w->WriteProgram();
        }
    }

};

void main()
{
    //紧急项目
    Work *emergencyProjects = new Work();
    emergencyProjects->SetState(new ForenoonState());
    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

    //完成工作，不需要再加班了
    //emergencyProjects->SetFinish();

    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

    emergencyProjects->SetTime();
    emergencyProjects->WriteProgram();

}