備忘錄模式（Memonto）：在不破壞封裝性的前提下，捕獲一個物件的內部狀態，並在該物件之外儲存這個狀態，這樣以後就可將該物件恢復到原先儲存的狀態。

package memento;

/**
 * 備忘錄模式(Memento)
 * 遊戲角色
 */
public class GameRole {

    private int vit;
    private int atk;
    private int def;

    public int getVit() {
        return vit;
    }

    public void setVit(int vit) {
        this.vit = vit;
    }

    public int getAtk() {
        return atk;
    }

    public void setAtk(int atk) {
        this.atk = atk;
    }

    public int getDef() {
        return def;
    }

    public void setDef(int def) {
        this.def = def;
    }

    // 狀態顯示
    public void stateDisplay() {
        System.out.println("角色當前狀態：");
        System.out.println("體力：" + this.vit);
        System.out.println("體力：" + this.atk);
        System.out.println("體力：" + this.def);
        System.out.println(" ");
    }

    // 獲得初始狀態
    public void getInitState() {
        this.vit = 100;
        this.atk = 100;
        this.def = 100;
    }

    // 戰鬥
    public void fight() {
        this.vit = 0;
        this.atk = 0;
        this.def = 0;
    }


    // 儲存角色狀態
    public RoleStateMemento saveState() {
        return new RoleStateMemento(vit, atk, def);
    }

    // 恢復角色狀態
    public void recoveryState(RoleStateMemento memento) {
        this.vit = memento.getVit();
        this.atk = memento.getAtk();
        this.def = memento.getDef();
    }

}
 

package memento;

/**
 * 備忘錄模式(Memento)
 * 遊戲角色狀態儲存箱
 */
public class RoleStateMemento {

    private int vit;
    private int atk;
    private int def;

    public RoleStateMemento(int vit, int atk, int def) {
        this.vit = vit;
        this.atk = atk;
        this.def = def;
    }

    public int getVit() {
        return vit;
    }

    public void setVit(int vit) {
        this.vit = vit;
    }

    public int getAtk() {
        return atk;
    }

    public void setAtk(int atk) {
        this.atk = atk;
    }

    public int getDef() {
        return def;
    }

    public void setDef(int def) {
        this.def = def;
    }

}
 

package memento;

/**
 * 備忘錄模式(Memento)
 * 遊戲角色狀態管理者
 */
public class RoleStateCaretaker {

    private RoleStateMemento memento;

    public RoleStateMemento getMemento() {
        return memento;
    }

    public void setMemento(RoleStateMemento memento) {
        this.memento = memento;
    }

}
 

package memento;

/**
 * 備忘錄模式(Memento)
 * 客戶端main方法
 */
public class Client {

    public static void main(String[] args) {
        // 打Boss前
        GameRole lixiaoyao = new GameRole();
        lixiaoyao.getInitState();
        lixiaoyao.stateDisplay();
        // 儲存進度
        RoleStateCaretaker stateAdmin = new RoleStateCaretaker();
        stateAdmin.setMemento(lixiaoyao.saveState());
        // 打Boss時，GameOver了
        lixiaoyao.fight();
        lixiaoyao.stateDisplay();
        // 恢復之前狀態
        lixiaoyao.recoveryState(stateAdmin.getMemento());
        lixiaoyao.stateDisplay();
    }

}