public class Originator {
    private String state;//狀態(tài)
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
    //編寫一個方法，可以保存一個狀態(tài)對象Memento
    public Memento saveStateMemento(){
        return new Memento(state);
    }
    public void getStateFromMemento (Memento memento){
        state = memento.getState();
    }
}

public class Memento {
    private String state;
    public Memento(String state) {
        this.state = state;
    }
    public String getState() {
        return state;
    }
}

public class Caretaker {
    //List集合中會有很多備忘錄對象
    private List<Memento> mementoList = new ArrayList<>();
    public void add(Memento memento) {
        mementoList.add(memento);
    }
    //獲取到第index個Origintor的備忘錄對象
    public Memento get(int index){
        return mementoList.get(index);
    }
}

//原發(fā)器，需要保存對象的狀態(tài)
@Data
@AllArgsConstructor
public class Chessman
{
    private String label;//當(dāng)前棋子的名字: 車，炮，馬
    private Integer x,y;//當(dāng)前棋子的坐標
    //保存當(dāng)前對象的狀態(tài)--備份數(shù)據(jù)
    public ChessmanMemento save()
    {
        return new ChessmanMemento(label,x,y);
    }
    //恢復(fù)當(dāng)前對象的狀態(tài)
    public void restore(ChessmanMemento chessmanMemento)
    {
        this.label=chessmanMemento.getLabel();
        this.x=chessmanMemento.getX();
        this.y=chessmanMemento.getY();
    }
    //展示當(dāng)前對象的狀態(tài)
    public void show()
    {
        System.out.println(
                String.format("棋子: %s ,位置: [%d,%d]",label,x,y)
        );
    }
}

//負責(zé)備份的棋子狀態(tài)
@Data
@AllArgsConstructor
public class ChessmanMemento
{
    private String label;
    private Integer x,y;
}

//負責(zé)保存多個備份對象
public class MementoCaretaker
{
   //記錄當(dāng)前所處的備份狀態(tài)
   Integer index=-1;//一開始沒有備份數(shù)據(jù)
  //通過一個List集合保存多個備份對象
    List<ChessmanMemento> chessmanMementoLinkedList= Lists.newLinkedList();
  //悔棋操作--恢復(fù)到上一個備忘錄狀態(tài)
    public  ChessmanMemento getMemento()
    {
        if(index<=0)
        {
            throw new IndexOutOfBoundsException("已經(jīng)無棋可悔了");
        }
        this.index--;//當(dāng)前所處的備份狀態(tài)減去一
        //將當(dāng)前狀態(tài)之后的狀態(tài)全部清空
        //保留前index個元素，并將流收集到List中
        chessmanMementoLinkedList = chessmanMementoLinkedList.stream()
                .limit(this.index+1).collect(Collectors.toList());
        return chessmanMementoLinkedList.get(index);
    }
    //下棋---增加新的備份對象
    public void addMemento(ChessmanMemento chessmanMemento)
    {
        index++;
        chessmanMementoLinkedList.add(chessmanMemento);
    }
}

//客戶端
public class Client
{
  //維護一個守護者對象
  MementoCaretaker mementoCaretaker=new MementoCaretaker();
 //下棋
    public void play(Chessman chessman)
    {
        //通過調(diào)用備份返回，返回一個備份對象，添加進備份集合中去
        mementoCaretaker.addMemento(chessman.save());
    }
 //悔棋
    public void undo(Chessman chessman)
    {
        //得到上一次記錄的備份狀態(tài)對象
        ChessmanMemento memento = mementoCaretaker.getMemento();
        //調(diào)用恢復(fù)功能
        chessman.restore(memento);
    }
}

public class Test
{
    public static void main(String[] args) {
        //創(chuàng)建棋子對象
        Chessman chessman=new Chessman("車",1,1);
        //創(chuàng)建一個客戶端
        Client client=new Client();
        client.play(chessman);
        chessman.show();
        chessman=new Chessman("馬",2,0);
        client.play(chessman);
        chessman.show();
        //悔棋
        client.undo(chessman);
        chessman.show();
        client.undo(chessman);
        chessman.show();
    }
}