1 /**
 2  * Created by xc on 2019/11/23
 3  * 生成隨機密碼：6位數字
 4  */
 5 public class Test7_4 {
 6 
 7     public static void main(String[] args) {
 8         System.out.println(randomPassword());//382630
 9     }
10 
11     public static String randomPassword() {
12         char[] chars = new char[6];
13         Random rnd = new
 
 Random();
14         for (int i = 0; i < 6; i++) {
15             chars[i] = (char) ('0' + rnd.nextInt(10));
16         }
17         return new String(chars);
18     }
19 
20 }

 1 /**
 2  * Created by xc on 2019/11/23
 3  * 生成隨機密碼：簡單8位
 4  * 8位密碼，字元可能由大寫字母、小寫字母、數字和特殊符號組成
 5  */
 6 public class Test7_5 {
 
 7 
 8     private static final String SPECIAL_CHARS = "!@#$%^&*_=+-/";
 9 
10     public static void main(String[] args) {
11         System.out.println(randomPassword());//ejgY^14*
12     }
13 
14     private static char nextChar(Random rnd) {
15         switch (rnd.nextInt(4)) {
16             case
 
 0:
17                 return (char) ('a' + rnd.nextInt(26));
18             case 1:
19                 return (char) ('A' + rnd.nextInt(26));
20             case 2:
21                 return (char) ('0' + rnd.nextInt(10));
22             default:
23                 return SPECIAL_CHARS.charAt(rnd.nextInt(SPECIAL_CHARS.length()));
24         }
25     }
26 
27     public static String randomPassword() {
28         char[] chars = new char[8];
29         Random rnd = new Random();
30         for (int i = 0; i < 8; i++) {
31             chars[i] = nextChar(rnd);
32         }
33         return new String(chars);
34     }
35 
36 }

 1 /**
 2  * Created by xc on 2019/11/23
 3  * 生成隨機密碼：複雜8位
 4  */
 5 public class Test7_6 {
 6 
 7     private static final String SPECIAL_CHARS = "!@#$%^&*_=+-/";
 8 
 9     public static void main(String[] args) {
10         System.out.println(randomPassword());//Q*82-/zQ
11     }
12 
13     private static int nextIndex(char[] chars, Random rnd) {
14         int index = rnd.nextInt(chars.length);
15         while (chars[index] != 0) {
16             index = rnd.nextInt(chars.length);
17         }
18         return index;
19     }
20 
21     private static char nextSpecialChar(Random rnd) {
22         return SPECIAL_CHARS.charAt(rnd.nextInt(SPECIAL_CHARS.length()));
23     }
24 
25     private static char nextUpperlLetter(Random rnd) {
26         return (char) ('A' + rnd.nextInt(26));
27     }
28 
29     private static char nextLowerLetter(Random rnd) {
30         return (char) ('a' + rnd.nextInt(26));
31     }
32 
33     private static char nextNumLetter(Random rnd) {
34         return (char) ('0' + rnd.nextInt(10));
35     }
36 
37     public static String randomPassword() {
38         char[] chars = new char[8];
39         Random rnd = new Random();
40         chars[nextIndex(chars, rnd)] = nextSpecialChar(rnd);
41         chars[nextIndex(chars, rnd)] = nextUpperlLetter(rnd);
42         chars[nextIndex(chars, rnd)] = nextLowerLetter(rnd);
43         chars[nextIndex(chars, rnd)] = nextNumLetter(rnd);
44         for (int i = 0; i < 8; i++) {
45             if (chars[i] == 0) {
46                 chars[i] = nextChar(rnd);
47             }
48         }
49         return new String(chars);
50     }
51 
52     private static char nextChar(Random rnd) {
53         switch (rnd.nextInt(4)) {
54             case 0:
55                 return (char) ('a' + rnd.nextInt(26));
56             case 1:
57                 return (char) ('A' + rnd.nextInt(26));
58             case 2:
59                 return (char) ('0' + rnd.nextInt(10));
60             default:
61                 return SPECIAL_CHARS.charAt(rnd.nextInt(SPECIAL_CHARS.length()));
62         }
63     }
64 
65 }