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; }
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