Java随机字符串：随机数字字符串，工具类

 1 import java.util.Date;
 2 import java.util.Random;
 3 import java.util.UUID;
 4 
 5 /**
 6  * @Name RandomStringUtil
 7  * @Descr 生成随机字符串
 8  * @author dx
 9  * @date 2015年10月15日下午2:36:05
10  */
11 public class RandomStringUtil {
12     /**
13      * @param passLength
14      *            : 要生成多少长度的字符串
15      * @param type
16      *            : 需要哪种类型
17      * @return 根据传入的type来判定
18      */
19     
20     // 可以根据自己需求来删减下面的代码，不要要的类型可以删掉
21      
22     // type=0：纯数字(0-9)
23     // type=1：全小写字母(a-z)
24     // type=2：全大写字母(A-Z)
25     // type=3: 数字+小写字母
26     // type=4: 数字+大写字母
27     // type=5：大写字母+小写字母
28     // type=6：数字+大写字母+小写字母
29     // type=7：固定长度33位：根据UUID拿到的随机字符串，去掉了四个"-"(相当于长度33位的小写字母加数字)
30 
31     public static String getRandomCode(int passLength, int type) {
32         StringBuffer buffer = null;
33         StringBuffer sb = new StringBuffer();
34         Random r = new Random();
35         r.setSeed(new Date().getTime());
36         switch (type) {
37         case 0:
38             buffer = new StringBuffer("0123456789");
39             break;
40         case 1:
41             buffer = new StringBuffer("abcdefghijklmnopqrstuvwxyz");
42             break;
43         case 2:
44             buffer = new StringBuffer("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
45             break;
46         case 3:
47             buffer = new StringBuffer("0123456789abcdefghijklmnopqrstuvwxyz");
48             break;
49         case 4:
50             buffer = new StringBuffer("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");
51             break;
52         case 5:
53             buffer = new StringBuffer("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
54             break;
55         case 6:
56             buffer = new StringBuffer("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");
57             sb.append(buffer.charAt(r.nextInt(buffer.length() - 10)));
58             passLength -= 1;
59             break;
60         case 7:
61             String s = UUID.randomUUID().toString();
62             sb.append(s.substring(0, 8) + s.substring(9, 13) + s.substring(14, 18) + s.substring(19, 23) + s.substring(24));
63         }
64 
65         if (type != 7) {
66             int range = buffer.length();
67             for (int i = 0; i < passLength; ++i) {
68                 sb.append(buffer.charAt(r.nextInt(range)));
69             }
70         }
71         return sb.toString();
72     }
73 }