java GUID生成器 产生随机GUID的方法

1. package test;
2.  
3. import java.net.*;
4. import java.util.*;
5.  
6. import java.security.MessageDigest;
7. import java.security.NoSuchAlgorithmException;
8. import java.security.SecureRandom;
9.  
10. /**
11. * <p>描述: GUID生成器，参考了来自www.JavaExchange.com的RandomGUID</p>
12. */
13. public class GuidGenerator extends Object
14. {
15. private static Random myRand; //基本java随机对象
16. private static SecureRandom mySecureRand; //安全随机对象
17.  
18. private static String s_id; //ip地址字符串
19.  
20. static
21. {
22. mySecureRand = new SecureRandom();
23. //用安全随机对象产生一随机数并用该随机数初始化基本java随机对象
24. long secureInitializer = mySecureRand.nextLong();
25. myRand = new Random(secureInitializer);
26.  
27. try
28. {
29. //获得当前主机的ip地址字符串
30. s_id = InetAddress.getLocalHost().toString();
31. }
32. catch (UnknownHostException e)
33. {
34. e.printStackTrace();
35. }
36. }
37.  
38. /**
39. * 缺省构造器
40. */
41. public GuidGenerator()
42. {
43. }
44.  
45. /**
46. * 缺省的产生随机GUID的方法
47. * @return 正确返回32字节的字符串，错误则返回长度为零的字符串
48. */
49. public static String genRandomGUID()
50. {
51. return genRandomGUID(false);
52. }
53.  
54. /**
55. * 产生随机GUID的方法,考虑产生GUID的效率，将来可以应用设计模式，先生成一堆id并缓存
56. * @param secure true : 带安全选项，用安全随机数对象生成
57. * false : 不带安全选项，用基本随机数对象生成
58. * @return 正确返回32字节的字符串，错误则返回长度为零的字符串
59. */
60. public static String genRandomGUID(boolean secure)
61. {
62. String valueBeforeMD5 = ""; //消息消化对象消化前的字符串
63. String valueAfterMD5 = ""; //经消息消化对象消化后的GUID字符串
64.  
65. MessageDigest md5 = null; //消息消化对象
66. StringBuffer sbValueBeforeMD5 = new StringBuffer();
67.  
68. try
69. {
70. md5 = MessageDigest.getInstance("MD5");
71. }
72. catch (NoSuchAlgorithmException e)
73. {
74. System.out.println("Error: " + e);
75. return valueBeforeMD5;
76. }
77.  
78. long time = System.currentTimeMillis(); //获得系统时间
79. long rand = 0; //随机数
80.  
81. if (secure) //用安全随机对象获得随机数
82. {
83. rand = mySecureRand.nextLong();
84. }
85. else
86. //用基本随机对象获得随机数
87. {
88. rand = myRand.nextLong();
89. }
90.  
91. //拼接组成GUID的各个信息
92. sbValueBeforeMD5.append(s_id);
93. sbValueBeforeMD5.append(":");
94. sbValueBeforeMD5.append(Long.toString(time));
95. sbValueBeforeMD5.append(":");
96. sbValueBeforeMD5.append(Long.toString(rand));
97. valueBeforeMD5 = sbValueBeforeMD5.toString();
98. md5.update(valueBeforeMD5.getBytes());
99. byte[] array = md5.digest(); //消息消化对象进行消化动作，返回128bit
100.  
101. String strTemp = "";
102. for (int i = 0; i < array.length; i++)
103. {
104. strTemp = (Integer.toHexString(array[i] & 0XFF));
105. if (strTemp.length() == 1)
106. {
107. valueAfterMD5 = valueAfterMD5 + "0" + strTemp;
108. }
109. else
110. {
111. valueAfterMD5 = valueAfterMD5 + strTemp;
112. }
113. }
114. //GUID标准格式如：C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
115. return valueAfterMD5.toUpperCase();
116. }
117.  
118. public static void main(String args[])
119. {
120. for (int i = 1; i < 10; i++)
121. {
122. System.out.println(Integer.toString(i) + " : " + genRandomGUID());
123. }
124. }
125. }

运行结果

1. 1 : BDE4A953342C1B44CF186E6CA30E54FC
2. 2 : C21659FA319D0AECBC5F56BF07055B12
3. 3 : 9B0FE8CC5EB5E5E509BAF50730A163AF
4. 4 : 674CAEF13B787AB1105AB15A5F6B0162
5. 5 : 38D4D67BA67301703D347C13D92B80CF
6. 6 : A66305848E697DB9F65F906ECF9A4E9F
7. 7 : F4317957D5A38FAC6220D77D49EF408C
8. 8 : 33CF7899B1DEA3E124935FC8312A3B6C
9. 9 : C87E0C364F4FEF7B84519C2C3AE2322D