设计模式之状态模式(State)

状态模式原理：随着状态的变化，对象的行为也发生变化

代码如下：

#include <iostream>
#include <string>
#include <list>
using namespace std;

class War;
class State
{
public:
	virtual void fire(War *war)
	{

	}
};

class War
{
public:
	War(State* state):m_state(state),m_day(0){}
	void Setday(int day)
	{
		m_day = day;
	}
	int Getday()
	{
		return m_day;
	}
	void SetState(State *state)
	{
		delete m_state;
		m_state = state;
	}
	void GetState()
	{
		m_state->fire(this);
	}
	~War(){delete m_state;}
private:
	State *m_state;
	int m_day;
};

class WarEndState:public State
{
public:
	virtual void fire(War *war)
	{
		cout << "we are in the end of war" <<endl;
	}
};

class WarMiddleState:public State
{
public:
	virtual void fire(War *war)
	{
		if (war->Getday() < 20)
		{
			cout << "we are in the middle of war" <<endl;
		}
		else
		{
			war->SetState(new WarEndState());
			war->GetState();
		}
	}
};

class WarBeforeState:public State
{
public:
	virtual void fire(War *war)
	{
		if (war->Getday() < 10)
		{
			cout << "we are in the before of war" <<endl;
		}
		else
		{
			war->SetState(new WarMiddleState());
			war->GetState();
		}
	}
};

int main()
{
	War *war = new War(new WarBeforeState());
	for (int i = 9;i < 30;i+=9)
	{
		war->Setday(i);
		war->GetState();
	}
	return 0;
}