设计模式--状态模式C++实现

#include<iostream>
using namespace std;

//前项声明
class Context;
//抽象状态类定义
class State
{
protected:
    State(){}
public:
    virtual~State() = 0
    {};
    void setContext(Context *x)
    {
        _context = x;
    }
    virtual void handler1() = 0;
    virtual void handler2() = 0;
private:
    Context *_context;
};

//具体状态定义
class ConcreteState1 :public State
{
public:
    ConcreteState1(){}
    ~ConcreteState1(){}

    void handler1()
    {
        cout << "ConcreteState1::handler1" << endl;
    }
    void handler2()
    {
        cout << "ConcreteState1::handler2" << endl;
    }
private:

};

//具体状态定义
class ConcreteState2 :public State
{
public:
    ConcreteState2(){}
    ~ConcreteState2(){}

    void handler1()
    {
        cout << "ConcreteState2::handler1" << endl;
    }
    void handler2()
    {
        cout << "ConcreteState2::handler2" << endl;
    }
private:

};

//环境类
class Context
{
public:
    Context()
    :Sta1(new ConcreteState1)
    ,Sta2(new ConcreteState2)
    {}
    State* getCurrentState()
    {
        return CurrentState;
    }
    void SetCurrentState(State* s)
    {
        CurrentState = s;
        CurrentState->setContext(this);
    }
    void handler1()
    {
        CurrentState->handler1();
    }
    void handler2()
    {
        CurrentState->handler2();
    }
    ~Context(){}
private:
    //当前状态则是所有状态中的一种
    State *CurrentState;
    //所有状态应当定义为static比较合适
    State *Sta1;
    State *Sta2;
};