备忘录模式

备忘录模式

林小果12024-09-30 12:51

备忘录（Memento）模式：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，以便以后当需要时能将该对象恢复到原先保存的状态。该模式又叫快照模式。

案例

每次玩游戏时从服务器读取存档，退出后保存存档

存档类：

java 复制代码

public class GameRecoder {
    Integer id;
    Integer level;

    public GameRecoder(Integer id, Integer level) {
        this.id = id;
        this.level = level;
    }

    @Override
    public String toString() {
        return "GameRecoder{" +
                "id=" + id +
                ", level=" + level +
                '}';
    }
}

服务器：

java 复制代码

public class GameServer {
    Map<Integer,GameRecoder> map = new HashMap<>();
    int cur = 0;

    {
        cur++;
        GameRecoder gameRecoder = new GameRecoder(cur, 1);
        map.put(cur,gameRecoder);

    }

    public void addRecord(Integer level){
        cur++;
        GameRecoder gameRecoder = new GameRecoder(cur, level);
        map.put(cur,gameRecoder);
        System.out.println("添加存档："+gameRecoder);
    }

    public GameRecoder getRecord(){
        System.out.println("读取存档："+map.get(cur));
        return map.get(cur);
    }
}

游戏：

java 复制代码

public class MyGame {
    private Integer level;

    GameServer server = new GameServer();

    public void play(){
        GameRecoder record = server.getRecord();
        level = record.level;
        System.out.println("开始游戏，当前等级："+level);
        level++;
    }

    // 存档
    private void save(){
        server.addRecord(level);
    }

    public void exit(){
        System.out.println("退出游戏");
        save();
    }
}

测试：

java 复制代码

public class Main {
    public static void main(String[] args) {
        MyGame myGame = new MyGame();
        myGame.play();

        myGame.exit();
        myGame.play();
    }
}