核心： 把状态的判断逻辑转移到表示不同状态的一系列类当中，可以把复杂的判断逻辑简化
例子：
class State //状态接口
{
public:
virtual void show() = 0;
}; class NormalState: public State //正常状态
{
public:
virtual void show()
{
cout << "Normal state, communicate success." << endl;
}
}; class CritcalState: public State //紧急状态
{
public:
virtual void show()
{
cout << "Critcal state, communicate failed." << endl;
}
};
class Communicate
{
public:
void criticalState() //紧急状态下对应的操作
{
CritcalState().show();
} void normalState() //正常状态下对应的操作
{
NormalState().show();
}
};
int main()
{
Communicate c;
c.criticalState();
c.normalState();
return 0;
}