备忘录模式 （c++实现）
模式定义
备忘录（Memento）: 在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可以将该对象恢复到原先保存的状态。
模式动机
- 备忘录模式比较适用于功能比较复杂的，但需要维护或记录属性历史的类，或者需要保存的属性只是众多属性中的一小部分时，LieKong可以根据stateManager保存的BaseState信息换遇到前一状态。
UML类图
设计介绍
-
LieKong
游戏角色，拥有属性BaseState。一个可以回到过去的技能UnleashSkills
-
BaseState
封装任务状态：三维坐标和血量两个状态
-
StateManager
记录角色前一个状态
源码实现
- baseState.h
#ifndef BASESTATE_H
#define BASESTATE_H
#include <QObject>
class BaseState : public QObject
{
Q_OBJECT
public:
struct POSITION
{
int x;
int y;
int z;
};
explicit BaseState(QObject *parent = nullptr);
explicit BaseState(POSITION pos, int xl, QObject *parent = nullptr);
BaseState(const BaseState& state);
BaseState& operator=(const BaseState& state);
void SetPositon(POSITION pos);
void SetXL(int xl);
void PrintState();
signals:
public slots:
private:
POSITION m_Position;//位置
int m_Xl;//血量
};
#endif // BASESTATE_H
- baseState.cpp
#include <QDebug>
#include "basestate.h"
BaseState::BaseState(QObject *parent)
{
}
BaseState::BaseState(POSITION pos, int xl, QObject *parent)
: QObject(parent), m_Position(pos), m_Xl(xl)
{
}
BaseState::BaseState(const BaseState &state)
{
if(this != &state)
{
this->m_Xl = state.m_Xl;
this->m_Position.x = state.m_Position.x;
this->m_Position.y = state.m_Position.y;
this->m_Position.z = state.m_Position.z;
}
}
BaseState &BaseState::operator=(const BaseState &state)
{
if(this != &state)
{
this->m_Xl = state.m_Xl;
this->m_Position.x = state.m_Position.x;
this->m_Position.y = state.m_Position.y;
this->m_Position.z = state.m_Position.z;
}
return *this;
}
void BaseState::SetPositon(POSITION pos)
{
m_Position.x = pos.x;
m_Position.y = pos.y;
m_Position.z = pos.z;
}
void BaseState::SetXL(int xl)
{
m_Xl = xl;
}
void BaseState::PrintState()
{
qDebug() << QString("现在的坐标是：x = %1, y = %2, z = %3;").arg(m_Position.x).arg(m_Position.y).arg(m_Position.z);
qDebug() << QString("现在的血量是：%1").arg(m_Xl);
qDebug() << endl;
}
- liekong.h
#ifndef LIEKONG_H
#define LIEKONG_H
#include <QObject>
#include <functional>
#include "basestate.h"
using skill1 = std::function<bool (int)>;
using skill2 = std::function<void(void)>;
using skill3 = std::function<void(void)>;
class Liekong : public QObject
{
Q_OBJECT
public:
explicit Liekong(QObject *parent = nullptr);
BaseState State();
void SetState(BaseState state);
void UnleashSkills(const skill1& skill);//释放时光倒回技能
void ChangeState();//改变状态
private:
BaseState CreateState();
signals:
public slots:
private:
BaseState m_State;
};
#endif // LIEKONG_H
- liekong.cpp
#include <QDebug>
#include "liekong.h"
Liekong::Liekong(QObject *parent) : QObject(parent)
{
CreateState();
}
BaseState Liekong::State()
{
m_State.PrintState();
return m_State;
}
void Liekong::SetState(BaseState state)
{
m_State= state;
}
BaseState Liekong::CreateState()
{
BaseState::POSITION pos;
pos.x = 20;
pos.y = 50;
pos.z = 67;
m_State = BaseState(pos, 100);
return m_State;
}
void Liekong::UnleashSkills(const skill1& skill)
{
int a = 0;
skill(a);
}
void Liekong::ChangeState()
{
BaseState::POSITION pos;
pos.x = 10;
pos.y = 10;
pos.z = 10;
m_State.SetPositon(pos);
m_State.SetXL(10);
}
- statemanager.h
#ifndef STATEMANAGER_H
#define STATEMANAGER_H
#include <QObject>
#include "basestate.h"
class StateManager : public QObject
{
Q_OBJECT
public:
explicit StateManager(QObject *parent = nullptr);
void SetState(const BaseState& state);
BaseState State();
signals:
public slots:
private:
BaseState m_State;
};
#endif // STATEMANAGER_H
- satemanager.cpp
#include "statemanager.h"
StateManager::StateManager(QObject *parent) : QObject(parent)
{
}
void StateManager::SetState(const BaseState& state)
{
m_State = state;
}
BaseState StateManager::State()
{
return m_State;
}
- main.cpp
/************************************
* @brief : 需要三个类，我们以 守望先锋 里的裂空的一个回到去过去的技能为背景写一个实现
* @author : wzx
* @date : 2020-04-30
* @project : Memento
*************************************/
#include <QCoreApplication>
#include <QDebug>
#include "liekong.h"
#include "statemanager.h"
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Liekong lk;
qDebug() << "初始状态：";
BaseState state = lk.State();
StateManager manage;
manage.SetState(state);
lk.ChangeState();
qDebug() << "更新后状态：";
lk.State();
BaseState state1 = manage.State();
lk.UnleashSkills([&lk, state1](int a){
lk.SetState(state1);
qDebug() << "param = " << a;
return true;
});
qDebug() << "还原后状态:";
lk.State();
return a.exec();
}
- 运行结果
初始状态：
"现在的坐标是：x = 20, y = 50, z = 67;"
"现在的血量是：100"
更新后状态：
"现在的坐标是：x = 10, y = 10, z = 10;"
"现在的血量是：10"
还原后状态:
"现在的坐标是：x = 20, y = 50, z = 67;"
"现在的血量是：100"
优点
- 封装细节，如果要更改保存的细节，也不会影响到客户端
