C++设计模式：备忘录模式

最新推荐文章于 2024-12-30 07:31:51 发布

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本文介绍了一种使用C++实现的备忘录模式，通过源代码详细展示了如何保存和恢复对象的状态，适用于需要保存和恢复状态的应用场景。通过Originator、Memento和CareTaker三个类的交互，实现了状态的保存和恢复功能。

一、源代码：

#include<iostream>
#include<memory>
#include<vector>

using namespace std;

class Memento
{
public:
    Memento(string state)
    {
        this->_state = state;
    }
    string getState()
    {
        return _state;
    }
private:
    string _state;
};

class Originator
{
public:
    void setState(string state)
    {
        this->_state = state;
    }
    string getState()
    {
        return _state;
    }
    shared_ptr<Memento> saveStateToMemento()
    {
        return make_shared<Memento>(_state);
    }
    void getStateFromMemento(shared_ptr<Memento> memento)
    {
        _state = memento->getState();
    }
private:
    string _state;
};

class CareTaker
{
public:
    void add(shared_ptr<Memento> state)
    {
        _mementoVector.push_back(state);
    }
    shared_ptr<Memento> get(int index)
    {
        return _mementoVector[index];
    }
private:
    vector<shared_ptr<Memento>> _mementoVector = {};
};

int main()
{
    shared_ptr<Originator> originator = make_shared<Originator>();
    shared_ptr<CareTaker> careTaker = make_shared<CareTaker>();
    originator->setState("State #1");
    originator->setState("State #2");
    careTaker->add(originator->saveStateToMemento());
    originator->setState("State #3");
    careTaker->add(originator->saveStateToMemento());
    originator->setState("State #4");

    cout<<"Current State: "<<originator->getState()<<endl;
    originator->getStateFromMemento(careTaker->get(0));
    cout<<"First saved State: "<<originator->getState()<<endl;
    originator->getStateFromMemento(careTaker->get(1));
    cout<<"Second saved State: "<<originator->getState();
}

二、运行结果：