2021.11.25
备忘录模式：多次撤销
改进课堂上的“用户信息操作撤销”实例，使得系统可以实现多次撤销（可以使用HashMap、ArrayList等集合数据结构实现）。java源代码：
（1）Caretaker.java：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
package shiyan20;import java.util.ArrayList;public class Caretaker { private ArrayList<Memento> mementos= new ArrayList<Memento>(); public Memento getMemento(int i) { return (Memento)mementos.get(i); } public void setMemento(Memento memento) { mementos.add(memento); } } |
（2）Client.java：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
package shiyan20;public class Client {public static void main(String a[]){ UserInfoDTO user=new UserInfoDTO(); Caretaker taker = new Caretaker(); user.setAccount("zhangsan"); user.setPassword("123456"); user.setTelNo("13000000000"); System.out.println("状态一："); taker.setMemento(user.saveMemento()); user.show(); System.out.println("---------------------------"); user.setPassword("111111"); user.setTelNo("13100001111"); System.out.println("状态二："); user.show(); taker.setMemento(user.saveMemento()); System.out.println("---------------------------"); user.setPassword("222222"); user.setTelNo("13100001111"); System.out.println("状态三："); user.show(); System.out.println("---------------------------"); System.out.println("回到状态二"); user.restoreMemento(taker.getMemento(1)); user.show(); System.out.println("---------------------------"); System.out.println("回到状态一"); user.restoreMemento(taker.getMemento(0)); user.show(); System.out.println("---------------------------"); }} |
（3）Memento.java：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
package shiyan20;public class Memento { private String account; private String password; private String telNo; public Memento(String account,String password,String telNo) { this.account=account; this.password=password; this.telNo=telNo; } public String getAccount() { return account; } public void setAccount(String account) { this.account=account; } public String getPassword() { return password; } public void setPassword(String password) { this.password=password; } public String getTelNo() { return telNo; } public void setTelNo(String telNo) { this.telNo=telNo; }} |
（4）UserInfoDTO.java：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
package shiyan20;/* * 用户信息类 */public class UserInfoDTO { private String account; private String password; private String telNo; public String getAccount() { return account; } public void setAccount(String account) { this.account=account; } public String getPassword() { return password; } public void setPassword(String password) { this.password=password; } public String getTelNo() { return telNo; } public void setTelNo(String telNo) { this.telNo=telNo; } public Memento saveMemento() { return new Memento(account,password,telNo); } public void restoreMemento(Memento memento) { this.account=memento.getAccount(); this.password=memento.getPassword(); this.telNo=memento.getTelNo(); } public void show() { System.out.println("Account:" + this.account); System.out.println("Password:" + this.password); System.out.println("TelNo:" + this.telNo); }} |
实现截图：
