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) = 0;//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()<21){
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()<17)
{
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()<13)
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()<12)
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(9);
emergencyProjects->WriteProgram();

emergencyProjects->SetTime(10);
emergencyProjects->WriteProgram();

emergencyProjects->SetTime(12);
emergencyProjects->WriteProgram();

emergencyProjects->SetTime(14);
emergencyProjects->WriteProgram();

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

emergencyProjects->SetTime(19);
emergencyProjects->WriteProgram();

emergencyProjects->SetTime(22);
emergencyProjects->WriteProgram();

}