设计模式之—备忘录模式<Memento Pattern>

备忘录模式：在不破坏封装行的前提下，捕获一个对象的内在状态，并在该对象之外保存这个状态，这样以后就可将该对象恢复到原来保存的状态。

发起备忘者类（Originator）

namespace MemoPattern.CLASS
{
    class Originator
    {
        private string state;
        public string State
        {
            get { return state; }
            set { state = value; }
        }

        public Memento CreateMemento()
        {
            return new Memento(state);
        }

        public void ReadMemento(Memento memento)
        {
            this.state = memento.State;
        }

        public void Show()
        {
            Console.WriteLine("当前状态是："+ state );
        }
    }
}

备忘录类（Memento）

namespace MemoPattern.CLASS
{
    class Memento
    {
        private string state;
        public Memento(string state)
        {
            this.state = state;
        }

        public string State
        {
            get { return state; }
        }
    }
}

备忘录管理类（Caretaker）

namespace MemoPattern.CLASS
{
    class Caretaker
    {
        private Memento memento;
        public Memento Memento
        {
            get { return memento; }
            set { memento = value; }
        }
    }
}

测试类（TestMain）

namespace MemoPattern
{
    class TestMain
    {
        static void Main(string[] args)
        {
            Originator person = new Originator();
            person.State = "开始游戏";
            person.Show();

            Caretaker manager = new Caretaker();
            manager.Memento = person.CreateMemento();

            person.State = "游戏失败";
            person.Show();

            person.ReadMemento(manager.Memento);
            person.Show();

            Console.Read();
        }
    }
}

测试结果：

以下是对备忘录模式的具体应用：以保存游戏进度为例

保存游戏者（GameRole）

namespace MementoPatternTest.CLASS
{
    class GameRole
    {
        private string attach;
        private string defense;
        private string life;
        /// <summary>
        /// 攻击力
        /// </summary>
        public string Attach
        {
            get { return attach; }
            set { attach = value; }
        }
        /// <summary>
        /// 防御力
        /// </summary>
        public string Defense
        {
            get { return defense; }
            set { defense = value; }
        }
        /// <summary>
        /// 生命力
        /// </summary>
        public string Life
        {
            get { return life; }
            set { life = value; }
        }
        /// <summary>
        /// 保存游戏备忘
        /// </summary>
        /// <returns></returns>
        public GameMemento SavaGameState()
        {
            return new GameMemento(life, attach, defense);
        }

        /// <summary>
        /// 获取保存的状态
        /// </summary>
        /// <param name="gameState"></param>
        public void RecoverGameState(GameMemento gameState)
        {
            this.attach = gameState.Attach;
            this.life = gameState.Life;
            this.defense = gameState.Defense;
        }

        /// <summary>
        /// 游戏初始状态
        /// </summary>
        public void InitGameState()
        {
            this.life = "100";
            this.attach = "100";
            this.Defense = "100";      
        }
        /// <summary>
        /// 游戏结束状态
        /// </summary>
        public void GameOverState()
        {
            this.life = "0";
            this.attach = "0";
            this.Defense = "0";
        }
        /// <summary>
        /// 状态显示
        /// </summary>
        public void StateShow()
        {
            Console.WriteLine("角色当前状态：生命力：{0},攻击力{1},防御力{2}.",life,attach,defense);
        }
    }
}

游戏备忘类（GameMemento）

namespace MementoPatternTest.CLASS
{
    class GameMemento
    {
        private string life;
        private string attach;
        private string defense;

        /// <summary>
        /// 攻击力
        /// </summary>
        public string Attach
        {
            get { return attach; } 
        }
        /// <summary>
        /// 生命力
        /// </summary>
        public string Life
        {
            get { return life; }
        }
        /// <summary>
        /// 防御力
        /// </summary>
        public string Defense
        {
            get { return defense; }
        }

        public GameMemento(string life,string attach,string defense)
        {
            this.life = life;
            this.attach = attach;
            this.defense = defense;
        }
    }
}

游戏备忘管理类（GameStateManage）

namespace MementoPatternTest.CLASS
{
    class GameStateManage
    {
        private GameMemento gameMemento;
        public GameMemento GameMemento
        {
            get { return gameMemento; }
            set { gameMemento = value; }
        }
    }

}

测试类（TestMain）

using MementoPatternTest.CLASS;
namespace MementoPatternTest
{
    class TestMain
    {
        static void Main(string[] args)
        {
            GameRole person = new GameRole();
            person.InitGameState();
            person.StateShow();

            GameStateManage gameManage = new GameStateManage();
            gameManage.GameMemento = person.SavaGameState();

            person.GameOverState();
            person.StateShow();

            person.RecoverGameState(gameManage.GameMemento);
            person.StateShow();

            Console.ReadLine();
        }
    }
}

测试结果：