备忘录模式实例1

1、以游戏的场景为例，我们来讲解这个备忘录模式，一游戏角色有生命力、攻击力、防御力等数据，在打Boss后如果效果不理想可以让游戏恢复到决斗前的状态。

2、玩家类

class GameRole
    { 
    //生命力
        public int Vitality { set; get; }
    //攻击力
        public int Attack { set; get; }
    //防御力
        public int Defense { set; get; }
    //状态显示
        public void StateDisplay()
        {
            Console.WriteLine("显示当前状态：");
            Console.WriteLine("体力：{0}",this.Vitality);
            Console.WriteLine("攻击力：{0}",this.Attack);
            Console.WriteLine("防御力： {0}",this.Defense);
        }
    //获得初始状态
        public void GetInitState()
        {
            this.Vitality = 100;
            this.Attack = 100;
            this.Defense = 100;
        }
    //战斗
        public void Fight()
        {
            this.Vitality = 0;
            this.Attack = 0;
            this.Defense = 0;
        }
    }

3、客户端类

static void Main(string[] args)
        {
            //大战boss前
            Console.WriteLine("#############_战boss前_#################");
            GameRole gr = new GameRole();
            gr.GetInitState();
            gr.StateDisplay();

            //通过新的实例来保存进度
            GameRole backup = new GameRole();
            backup.Vitality = gr.Vitality;
            backup.Defense = gr.Defense;
            backup.Attack = gr.Attack;

            //战boss后
            Console.WriteLine("#############_战boss后_#################");
            gr.Fight();
            gr.StateDisplay();

            //恢复之前的状态
            Console.WriteLine("#############_恢复之前的状态_#################");
            gr.Vitality = backup.Vitality;
            gr.Defense = backup.Defense;
            gr.Attack = backup.Attack;
            gr.StateDisplay();

            Console.Read();


        }

4、这样写问题主要在于客户端的调用，这样把整个游戏角色的细节暴露给了客户端，你的客户端的职责过大，我们希望可以把这些游戏角色的存取状态细节封装起来，而且最好是封装在外部的类当中，以体现职责分离。

5、到这里我们就要用到备忘模式

定义：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。这样以后就可将该对象恢复到原先保存的状态。

6、现在我们来改造这个代码，首先要有一个存储状态的类

class RoleStateMemento
    {
        public int Vitality { set; get; }
        public int Attack { set; get; }
        public int Defense { set; get; }
        public RoleStateMemento(int vit, int att, int def)
        {
            this.Vitality = vit;
            this.Attack = att;
            this.Defense = def;

        }
    }

7、改造玩家类

 class GameRole
    { 
    //生命力
        public int Vitality { set; get; }
    //攻击力
        public int Attack { set; get; }
    //防御力
        public int Defense { set; get; }

    //保存状态
        public RoleStateMemento SaveState()
        {
            return new RoleStateMemento(Vitality, Attack, Defense);
        }

    //恢复状态
        public void RecoveryState(RoleStateMemento rs)
        {
            this.Vitality = rs.Vitality;
            this.Attack = rs.Attack;
            this.Defense = rs.Defense;
        }
    //状态显示
        public void StateDisplay()
        {
            Console.WriteLine("显示当前状态：");
            Console.WriteLine("体力：{0}",this.Vitality);
            Console.WriteLine("攻击力：{0}",this.Attack);
            Console.WriteLine("防御力： {0}",this.Defense);
        }
    //获得初始状态
        public void GetInitState()
        {
            this.Vitality = 100;
            this.Attack = 100;
            this.Defense = 100;
        }
    //战斗
        public void Fight()
        {
            this.Vitality = 0;
            this.Attack = 0;
            this.Defense = 0;
        }
    }

8、还要有一个管理角色状态的类

class RoleStateCaretaker
    {
        public RoleStateMemento rs;
    }

9、客户端代码

static void Main(string[] args)
        {
            //大战boss前
            Console.WriteLine("#############_战boss前_#################");
            GameRole gr = new GameRole();
            gr.GetInitState();
            gr.StateDisplay();

            //保存进度
            RoleStateCaretaker rc = new RoleStateCaretaker();
            rc.roleState = gr.SaveState();


            //战boss后
            Console.WriteLine("#############_战boss后_#################");
            gr.Fight();
            gr.StateDisplay();

            //恢复之前的状态
            Console.WriteLine("#############_恢复之前的状态_#################");
            gr.RecoveryState(rc.roleState);
            gr.StateDisplay();

            Console.Read();


        }