备忘录模式实例-象棋“悔棋”的实现

本例需提前了解：

备忘录模式

UML图

象棋原发器类

public class ChessmanOriginator {
    
    
	private String name;//各种状态
	private int x;//各种状态
	private int y;//各种状态

	public ChessmanOriginator(String name, int x, int y) {
    
    
		this.name = name;
		this.x = x;
		this.y = y;
	}

	public ChessmanOriginator() {
    
    
	}

	public String getName() {
    
    
		return name;
	}

	public void setName(String name) {
    
    
		this.name = name;
	}

	public int getX() {
    
    
		return x;
	}

	public void setX(int x) {
    
    
		this.x = x;
	}

	public int getY() {
    
    
		return y;
	}

	public void setY(int y) {
    
    
		this.y = y;
	}

	public ChessmanMemento CreateChessmanMemento() throws CloneNotSupportedException {
    
    
		return (ChessmanMemento) (new ChessmanMemento(name, x, y)).clone();
    //以原型模式中克隆的方式创造备忘录类实例并返回
	}

	public void SetChessmanMemento(ChessmanMemento memento) {
    
    //用备忘录类恢复状态
		this.name = memento.getName();
		this.x = memento.getX();
		this.y = memento.getY();
	}

	public void Show() {
    
    
		System.out.println("棋子：" + name + "坐标：" + x + "," + y);
	}

}

象棋备忘录类

public class ChessmanMemento implements Cloneable {
    
    //继承克隆接口
	private String name;
	private int x;
	private int y;

	public ChessmanMemento(String name, int x, int y) {
    
    
		this.name = name;
		this.x = x;
		this.y = y;
	}

	public ChessmanMemento() {
    
    
	}

	@Override
	protected Object clone() throws CloneNotSupportedException {
    
    
		return (ChessmanMemento) super.clone();
	}

	public String getName() {
    
    
		return name;
	}

	public void setName(String name) {
    
    
		this.name = name;
	}

	public int getX() {
    
    
		return x;
	}

	public void setX(int x) {
    
    
		this.x = x;
	}

	public int getY() {
    
    
		return y;
	}

	public void setY(int y) {
    
    
		this.y = y;
	}

}

管理者类

public class ChessmanCaretaker {
    
    

	public ChessmanCaretaker() {
    
    
	}

	private List<ChessmanMemento> mementoList = new ArrayList<ChessmanMemento>();

	public ChessmanMemento huiQi() {
    
    // 确保每一步都被保存下来
		int index = mementoList.size();
		if (index >= 2) {
    
    //如果保存了前一状态
			ChessmanMemento c = mementoList.get(index - 2);
			mementoList.remove(index - 1);
			return c;
		} else {
    
    
			ChessmanMemento c = new ChessmanMemento("空", 0, 0);
			return c;
		}

	}

	public void setMemento(ChessmanMemento memento) {
    
    
		mementoList.add(memento);
	}

}

客户端类

public class Client {
    
    

	public static void main(String[] args) {
    
    
		ChessmanOriginator Co = new ChessmanOriginator();
		ChessmanCaretaker Cc = new ChessmanCaretaker();

		Co.setName("炮1");
		Co.setX(7);
		Co.setY(2);
		Co.Show();
		try {
    
    
			Cc.setMemento(Co.CreateChessmanMemento());//保存到备忘录
		} catch (CloneNotSupportedException e) {
    
    
			e.printStackTrace();
		}

		Co.setName("马1");
		Co.setX(7);
		Co.setY(1);
		Co.Show();
		try {
    
    
			Cc.setMemento(Co.CreateChessmanMemento());//保存到备忘录
		} catch (CloneNotSupportedException e) {
    
    
			e.printStackTrace();
		}

		Co.SetChessmanMemento(Cc.huiQi());// 悔棋
		Co.Show();

		Co.setName("兵1");
		Co.setX(7);
		Co.setY(1);
		Co.Show();
		try {
    
    
			Cc.setMemento(Co.CreateChessmanMemento());//保存到备忘录
		} catch (CloneNotSupportedException e) {
    
    
			e.printStackTrace();
		}

		Co.SetChessmanMemento(Cc.huiQi());// 悔棋
		Co.Show();

	}

}

运行效果