23种设计模式----备忘录模式----行为模式

文章信息

• 原文链接：https://jiayq.blog.csdn.net/article/details/84988668
• 发布时间：2018-12-13 14:57:04
• 阅读量：748
• 分类：java同时被 2 个专栏收录, 订阅专栏, 设计模式
• 标签：#23种设计模式, #备忘录模式, #行为模式, #类快照, #撤销重做

摘要

文章浏览阅读748次。本文深入探讨了备忘录设计模式，通过一个猜大小游戏的实例，详细讲解了如何使用备忘录模式保存和恢复对象状态，实现了游戏过程中玩家状态的回退功能。

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备忘录模式

• 1.什么是备忘录模式
• 2.角色说明
• 3.关系说明
• 4.实现方式
• 5.例子
• • 5.1文件结构
    • 5.2项目介绍
    • 5.3骰子类
    • 5.4玩家类
    • 5.5快照类
    • 5.6使用者
    • 5.7结果
• 6.扩展

23种设计模式
直达底部

1.什么是备忘录模式

现在许多的文本编辑器都有一些功能：
撤销，重做，历史记录等等。
显示生活中，遇到有意义的瞬间，大家就会拍照留念。
照片保存了那个瞬间的一些信息：所处的环境的信息，目标的信息。。。。

所以备忘录模式就是实现可以保存某个对象的状态信息的功能，保存之后在需要的情况下，随时可以让对象恢复到保存的状态。

2.角色说明

1.目标：被记录的对象
2.快照：保存的目标对象信息的类

3.关系说明

实现备忘录模式的核心思想：
首先，创建一个类，这个类根据被保存对象进行设计，这个类需要满足能够记录目标类的需要的信息这个条件。为了保护数据，这个新创建的类不能随意的被其他类访问，只能由目标类访问，其他类只有恢复的操作，不能有访问属性值的操作。

4.实现方式

首先快照类需要保证数据的安全性，所以快照类的属性应该是私有，这样即使其他的类继承快照类，也无法获取快照的属性值。
其次，因为目标类需要能够访问快照，所以快照类和目标需要在同一个包内：快照类设置自己的属性的访问方法的权限为包内。
如果目标类的属性值机密性高，那么可以吧目标类的属性访问方式设置为包内，这样只能由目标类和快照类相互访问。

方法的访问权限有包内这个还是有原因的。

5.例子

5.1文件结构

5.2项目介绍

本次做一个游戏：猜大小，很简单，但是要知道程序是我们写的，所以特权肯定要有了。所以本次猜大小游戏的特权就是每一句输了可以免单。怎么说呢，猜大小，赢了加5分，输了不加分(第二次输会扣分)。（最后结果还能输吗）

5.3骰子类

package dice;

import java.util.Random;

public class Dice {

	public static Integer getDice(){
		return new Random().nextInt(6) + 1;
	}
	
}

5.4玩家类

package player;

import java.util.Random;

public class Player {

	private Integer score;
	
	private String name;
	
	public Integer getScore() {
		return score;
	}

	public void setScore(Integer score) {
		this.score = score;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
	
	public boolean getplay(){
		return new Random().nextBoolean();
	}
	
	public Memento createMemento(){
		Memento memento = new Memento(name, score);
		return memento;
	}
	
}

5.5快照类

package player;

public class Memento {

	private String name;
	
	private Integer score;
	
	Memento(String name,Integer score) {
		this.name = name;
		this.score = score;
	}

	public Player reset(Player player,Memento memento){
		player.setName(memento.getName());
		player.setScore(memento.getScore());
		return player;
	}
	
	String getName() {
		return name;
	}

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

	Integer getScore() {
		return score;
	}

	void setScore(Integer score) {
		this.score = score;
	}
	
}

5.6使用者

package client;

import java.util.Scanner;

import player.Memento;
import player.Player;
import dice.Dice;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		System.out.println("create player");
		Player player = new Player();
		System.out.println("please input name");
		player.setName(scanner.next());
		System.out.println(player.getName()+"player score is 0");
		player.setScore(0);
		
		System.out.println("it will be 100 times game");
		System.out.println("game start");
		
		System.out.println("create mem");
		Memento memento = player.createMemento();
		
		int sum = 0;
		
		for(int i = 0;i < 100;i++){
			System.out.println((i+1)+"'s gamer");
			boolean b = player.getplay();
			System.out.println(player.getName()+"player is "+(b ? "大" : "小"));
			int d = Dice.getDice();
			System.out.println("the dice is "+d);
			System.out.println("so the result is "
					+ ((d > 3 ? true : false) ? "大" : "小"));
			boolean res = (d > 3 && b) || (d <= 3 && !b);
			System.out.println((i+1)+"'s gamer is "+res);
			if(!res){
				System.out.println(player.getName()+"is false ,so please sub score");
				player.setScore(player.getScore() - 5 >= 0 ? player.getScore() - 5 : 0);
				System.out.println(player.getName()+"sub score is " + player.getScore());
				System.out.println("reset mem");
				player = memento == null ? player : memento.reset(player, memento);
				memento = null;
			} else {
				System.out.println(player.getName()+"is true ,so please add score");
				player.setScore(player.getScore() + 5);
				System.out.println(player.getName() + "'s score is"+player.getScore());
				System.out.println("save mem");
				memento = player.createMemento();
				sum++;
			}
		}
		System.out.println("now is over");
		
		System.out.println();
		System.out.println(player.getName()+" player have "+sum+"times game is true ");
		
	}

}

5.7结果

↓

create player
please input name
lili
liliplayer score is 0
it will be 100 times game
game start
create mem
1's gamer
liliplayer is 大
the dice is 1
so the result is 小
1's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
2's gamer
liliplayer is 大
the dice is 2
so the result is 小
2's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
3's gamer
liliplayer is 小
the dice is 3
so the result is 小
3's gamer is true
liliis true ,so please add score
lili's score is5
save mem
4's gamer
liliplayer is 小
the dice is 6
so the result is 大
4's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
5's gamer
liliplayer is 小
the dice is 4
so the result is 大
5's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
6's gamer
liliplayer is 小
the dice is 6
so the result is 大
6's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
7's gamer
liliplayer is 小
the dice is 2
so the result is 小
7's gamer is true
liliis true ,so please add score
lili's score is5
save mem
8's gamer
liliplayer is 小
the dice is 4
so the result is 大
8's gamer is false
liliis false ,so please sub score
lilisub score is 0
reset mem
9's gamer
liliplayer is 大
the dice is 5
so the result is 大
9's gamer is true
liliis true ,so please add score
lili's score is10
save mem
10's gamer
liliplayer is 大
the dice is 4
so the result is 大
10's gamer is true
liliis true ,so please add score
lili's score is15
save mem
11's gamer
liliplayer is 小
the dice is 6
so the result is 大
11's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
12's gamer
liliplayer is 小
the dice is 4
so the result is 大
12's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
13's gamer
liliplayer is 小
the dice is 2
so the result is 小
13's gamer is true
liliis true ,so please add score
lili's score is15
save mem
14's gamer
liliplayer is 小
the dice is 5
so the result is 大
14's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
15's gamer
liliplayer is 小
the dice is 6
so the result is 大
15's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
16's gamer
liliplayer is 小
the dice is 6
so the result is 大
16's gamer is false
liliis false ,so please sub score
lilisub score is 5
reset mem
17's gamer
liliplayer is 小
the dice is 2
so the result is 小
17's gamer is true
liliis true ,so please add score
lili's score is10
save mem
18's gamer
liliplayer is 小
the dice is 1
so the result is 小
18's gamer is true
liliis true ,so please add score
lili's score is15
save mem
19's gamer
liliplayer is 小
the dice is 5
so the result is 大
19's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
20's gamer
liliplayer is 小
the dice is 2
so the result is 小
20's gamer is true
liliis true ,so please add score
lili's score is20
save mem
21's gamer
liliplayer is 小
the dice is 5
so the result is 大
21's gamer is false
liliis false ,so please sub score
lilisub score is 15
reset mem
22's gamer
liliplayer is 小
the dice is 4
so the result is 大
22's gamer is false
liliis false ,so please sub score
lilisub score is 15
reset mem
23's gamer
liliplayer is 小
the dice is 4
so the result is 大
23's gamer is false
liliis false ,so please sub score
lilisub score is 10
reset mem
24's gamer
liliplayer is 大
the dice is 5
so the result is 大
24's gamer is true
liliis true ,so please add score
lili's score is15
save mem
25's gamer
liliplayer is 大
the dice is 6
so the result is 大
25's gamer is true
liliis true ,so please add score
lili's score is20
save mem
26's gamer
liliplayer is 小
the dice is 5
so the result is 大
26's gamer is false
liliis false ,so please sub score
lilisub score is 15
reset mem
27's gamer
liliplayer is 小
the dice is 3
so the result is 小
27's gamer is true
liliis true ,so please add score
lili's score is25
save mem
28's gamer
liliplayer is 大
the dice is 3
so the result is 小
28's gamer is false
liliis false ,so please sub score
lilisub score is 20
reset mem
29's gamer
liliplayer is 大
the dice is 4
so the result is 大
29's gamer is true
liliis true ,so please add score
lili's score is30
save mem
30's gamer
liliplayer is 小
the dice is 4
so the result is 大
30's gamer is false
liliis false ,so please sub score
lilisub score is 25
reset mem
31's gamer
liliplayer is 小
the dice is 2
so the result is 小
31's gamer is true
liliis true ,so please add score
lili's score is35
save mem
32's gamer
liliplayer is 小
the dice is 1
so the result is 小
32's gamer is true
liliis true ,so please add score
lili's score is40
save mem
33's gamer
liliplayer is 小
the dice is 3
so the result is 小
33's gamer is true
liliis true ,so please add score
lili's score is45
save mem
34's gamer
liliplayer is 小
the dice is 5
so the result is 大
34's gamer is false
liliis false ,so please sub score
lilisub score is 40
reset mem
35's gamer
liliplayer is 大
the dice is 3
so the result is 小
35's gamer is false
liliis false ,so please sub score
lilisub score is 40
reset mem
36's gamer
liliplayer is 大
the dice is 1
so the result is 小
36's gamer is false
liliis false ,so please sub score
lilisub score is 35
reset mem
37's gamer
liliplayer is 大
the dice is 6
so the result is 大
37's gamer is true
liliis true ,so please add score
lili's score is40
save mem
38's gamer
liliplayer is 大
the dice is 2
so the result is 小
38's gamer is false
liliis false ,so please sub score
lilisub score is 35
reset mem
39's gamer
liliplayer is 大
the dice is 2
so the result is 小
39's gamer is false
liliis false ,so please sub score
lilisub score is 35
reset mem
40's gamer
liliplayer is 小
the dice is 6
so the result is 大
40's gamer is false
liliis false ,so please sub score
lilisub score is 30
reset mem
41's gamer
liliplayer is 小
the dice is 5
so the result is 大
41's gamer is false
liliis false ,so please sub score
lilisub score is 25
reset mem
42's gamer
liliplayer is 小
the dice is 6
so the result is 大
42's gamer is false
liliis false ,so please sub score
lilisub score is 20
reset mem
43's gamer
liliplayer is 小
the dice is 2
so the result is 小
43's gamer is true
liliis true ,so please add score
lili's score is25
save mem
44's gamer
liliplayer is 大
the dice is 5
so the result is 大
44's gamer is true
liliis true ,so please add score
lili's score is30
save mem
45's gamer
liliplayer is 大
the dice is 5
so the result is 大
45's gamer is true
liliis true ,so please add score
lili's score is35
save mem
46's gamer
liliplayer is 小
the dice is 1
so the result is 小
46's gamer is true
liliis true ,so please add score
lili's score is40
save mem
47's gamer
liliplayer is 小
the dice is 2
so the result is 小
47's gamer is true
liliis true ,so please add score
lili's score is45
save mem
48's gamer
liliplayer is 大
the dice is 3
so the result is 小
48's gamer is false
liliis false ,so please sub score
lilisub score is 40
reset mem
49's gamer
liliplayer is 大
the dice is 5
so the result is 大
49's gamer is true
liliis true ,so please add score
lili's score is50
save mem
50's gamer
liliplayer is 小
the dice is 6
so the result is 大
50's gamer is false
liliis false ,so please sub score
lilisub score is 45
reset mem
51's gamer
liliplayer is 小
the dice is 5
so the result is 大
51's gamer is false
liliis false ,so please sub score
lilisub score is 45
reset mem
52's gamer
liliplayer is 大
the dice is 1
so the result is 小
52's gamer is false
liliis false ,so please sub score
lilisub score is 40
reset mem
53's gamer
liliplayer is 小
the dice is 1
so the result is 小
53's gamer is true
liliis true ,so please add score
lili's score is45
save mem
54's gamer
liliplayer is 大
the dice is 3
so the result is 小
54's gamer is false
liliis false ,so please sub score
lilisub score is 40
reset mem
55's gamer
liliplayer is 大
the dice is 5
so the result is 大
55's gamer is true
liliis true ,so please add score
lili's score is50
save mem
56's gamer
liliplayer is 大
the dice is 6
so the result is 大
56's gamer is true
liliis true ,so please add score
lili's score is55
save mem
57's gamer
liliplayer is 大
the dice is 5
so the result is 大
57's gamer is true
liliis true ,so please add score
lili's score is60
save mem
58's gamer
liliplayer is 小
the dice is 2
so the result is 小
58's gamer is true
liliis true ,so please add score
lili's score is65
save mem
59's gamer
liliplayer is 小
the dice is 6
so the result is 大
59's gamer is false
liliis false ,so please sub score
lilisub score is 60
reset mem
60's gamer
liliplayer is 小
the dice is 1
so the result is 小
60's gamer is true
liliis true ,so please add score
lili's score is70
save mem
61's gamer
liliplayer is 小
the dice is 6
so the result is 大
61's gamer is false
liliis false ,so please sub score
lilisub score is 65
reset mem
62's gamer
liliplayer is 大
the dice is 2
so the result is 小
62's gamer is false
liliis false ,so please sub score
lilisub score is 65
reset mem
63's gamer
liliplayer is 大
the dice is 3
so the result is 小
63's gamer is false
liliis false ,so please sub score
lilisub score is 60
reset mem
64's gamer
liliplayer is 大
the dice is 1
so the result is 小
64's gamer is false
liliis false ,so please sub score
lilisub score is 55
reset mem
65's gamer
liliplayer is 大
the dice is 4
so the result is 大
65's gamer is true
liliis true ,so please add score
lili's score is60
save mem
66's gamer
liliplayer is 大
the dice is 1
so the result is 小
66's gamer is false
liliis false ,so please sub score
lilisub score is 55
reset mem
67's gamer
liliplayer is 小
the dice is 4
so the result is 大
67's gamer is false
liliis false ,so please sub score
lilisub score is 55
reset mem
68's gamer
liliplayer is 大
the dice is 4
so the result is 大
68's gamer is true
liliis true ,so please add score
lili's score is60
save mem
69's gamer
liliplayer is 大
the dice is 6
so the result is 大
69's gamer is true
liliis true ,so please add score
lili's score is65
save mem
70's gamer
liliplayer is 大
the dice is 1
so the result is 小
70's gamer is false
liliis false ,so please sub score
lilisub score is 60
reset mem
71's gamer
liliplayer is 小
the dice is 2
so the result is 小
71's gamer is true
liliis true ,so please add score
lili's score is70
save mem
72's gamer
liliplayer is 大
the dice is 3
so the result is 小
72's gamer is false
liliis false ,so please sub score
lilisub score is 65
reset mem
73's gamer
liliplayer is 大
the dice is 5
so the result is 大
73's gamer is true
liliis true ,so please add score
lili's score is75
save mem
74's gamer
liliplayer is 小
the dice is 3
so the result is 小
74's gamer is true
liliis true ,so please add score
lili's score is80
save mem
75's gamer
liliplayer is 小
the dice is 2
so the result is 小
75's gamer is true
liliis true ,so please add score
lili's score is85
save mem
76's gamer
liliplayer is 大
the dice is 1
so the result is 小
76's gamer is false
liliis false ,so please sub score
lilisub score is 80
reset mem
77's gamer
liliplayer is 大
the dice is 6
so the result is 大
77's gamer is true
liliis true ,so please add score
lili's score is90
save mem
78's gamer
liliplayer is 大
the dice is 1
so the result is 小
78's gamer is false
liliis false ,so please sub score
lilisub score is 85
reset mem
79's gamer
liliplayer is 大
the dice is 3
so the result is 小
79's gamer is false
liliis false ,so please sub score
lilisub score is 85
reset mem
80's gamer
liliplayer is 大
the dice is 2
so the result is 小
80's gamer is false
liliis false ,so please sub score
lilisub score is 80
reset mem
81's gamer
liliplayer is 大
the dice is 4
so the result is 大
81's gamer is true
liliis true ,so please add score
lili's score is85
save mem
82's gamer
liliplayer is 大
the dice is 4
so the result is 大
82's gamer is true
liliis true ,so please add score
lili's score is90
save mem
83's gamer
liliplayer is 小
the dice is 3
so the result is 小
83's gamer is true
liliis true ,so please add score
lili's score is95
save mem
84's gamer
liliplayer is 大
the dice is 4
so the result is 大
84's gamer is true
liliis true ,so please add score
lili's score is100
save mem
85's gamer
liliplayer is 小
the dice is 5
so the result is 大
85's gamer is false
liliis false ,so please sub score
lilisub score is 95
reset mem
86's gamer
liliplayer is 小
the dice is 6
so the result is 大
86's gamer is false
liliis false ,so please sub score
lilisub score is 95
reset mem
87's gamer
liliplayer is 大
the dice is 4
so the result is 大
87's gamer is true
liliis true ,so please add score
lili's score is100
save mem
88's gamer
liliplayer is 大
the dice is 6
so the result is 大
88's gamer is true
liliis true ,so please add score
lili's score is105
save mem
89's gamer
liliplayer is 大
the dice is 5
so the result is 大
89's gamer is true
liliis true ,so please add score
lili's score is110
save mem
90's gamer
liliplayer is 小
the dice is 4
so the result is 大
90's gamer is false
liliis false ,so please sub score
lilisub score is 105
reset mem
91's gamer
liliplayer is 大
the dice is 5
so the result is 大
91's gamer is true
liliis true ,so please add score
lili's score is115
save mem
92's gamer
liliplayer is 小
the dice is 2
so the result is 小
92's gamer is true
liliis true ,so please add score
lili's score is120
save mem
93's gamer
liliplayer is 大
the dice is 1
so the result is 小
93's gamer is false
liliis false ,so please sub score
lilisub score is 115
reset mem
94's gamer
liliplayer is 小
the dice is 5
so the result is 大
94's gamer is false
liliis false ,so please sub score
lilisub score is 115
reset mem
95's gamer
liliplayer is 小
the dice is 5
so the result is 大
95's gamer is false
liliis false ,so please sub score
lilisub score is 110
reset mem
96's gamer
liliplayer is 小
the dice is 2
so the result is 小
96's gamer is true
liliis true ,so please add score
lili's score is115
save mem
97's gamer
liliplayer is 大
the dice is 5
so the result is 大
97's gamer is true
liliis true ,so please add score
lili's score is120
save mem
98's gamer
liliplayer is 大
the dice is 3
so the result is 小
98's gamer is false
liliis false ,so please sub score
lilisub score is 115
reset mem
99's gamer
liliplayer is 大
the dice is 2
so the result is 小
99's gamer is false
liliis false ,so please sub score
lilisub score is 115
reset mem
100's gamer
liliplayer is 小
the dice is 4
so the result is 大
100's gamer is false
liliis false ,so please sub score
lilisub score is 110
reset mem
now is over

lili player have 47times game is true 

↑

6.扩展

例子中每次只能保存一个快照。如果我们用一个list来保存，那么，我们可以任意回到某一局游戏时的状态。

直达顶部
23种设计模式