JAVA编码(3)——Java中定义不重复的32位UUID(主键)
package util; import java.net.InetAddress; import java.net.UnknownHostException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import java.util.Random; public class RandomGUIDUtil extends Object { public String valueBeforeMD5 = ""; public String valueAfterMD5 = ""; private static Random myRand; private static SecureRandom mySecureRand; private static String s_id; static { mySecureRand = new SecureRandom(); long secureInitializer = mySecureRand.nextLong(); myRand = new Random(secureInitializer); try { s_id = InetAddress.getLocalHost().toString(); } catch (UnknownHostException e) { System.out.println("构造带指定详细消息和嵌入异常!"); } } public static String newGuid(){ RandomGUIDUtil rdmGUID = null; try { rdmGUID = new RandomGUIDUtil(); } catch (Exception e) { e.printStackTrace(); } return rdmGUID.toString(); } public RandomGUIDUtil() throws Exception { getRandomGUID(false); } public RandomGUIDUtil(boolean secure) throws Exception { getRandomGUID(secure); } private void getRandomGUID(boolean secure) throws Exception { MessageDigest md5 = null; StringBuffer sbValueBeforeMD5 = new StringBuffer(); try { md5 = MessageDigest.getInstance("MD5"); } catch (NoSuchAlgorithmException e) { System.out.println("初始化MD5出错!"); throw new NoSuchAlgorithmException("初始化MD5出错!"); } try { long time = System.currentTimeMillis(); long rand = 0; if (secure) { rand = mySecureRand.nextLong(); } else { rand = myRand.nextLong(); } sbValueBeforeMD5.append(s_id); sbValueBeforeMD5.append(":"); sbValueBeforeMD5.append(Long.toString(time)); sbValueBeforeMD5.append(":"); sbValueBeforeMD5.append(Long.toString(rand)); valueBeforeMD5 = sbValueBeforeMD5.toString(); md5.update(valueBeforeMD5.getBytes()); byte[] array = md5.digest(); StringBuffer sb = new StringBuffer(); for (int j = 0; j < array.length; ++j) { int b = array[j] & 0xFF; if (b < 0x10) sb.append('0'); sb.append(Integer.toHexString(b)); } valueAfterMD5 = sb.toString(); } catch (Exception e) { System.out.println("获得MD5加密码出错!"); throw new Exception("初始化MD5出错!"); } } public String toString() { String raw = valueAfterMD5.toUpperCase(); StringBuffer sb = new StringBuffer(); sb.append(raw.substring(0, 8)); sb.append(raw.substring(8, 12)); sb.append(raw.substring(12, 16)); sb.append(raw.substring(16, 20)); sb.append(raw.substring(20)); return sb.toString(); } public static void main(String[] args) throws Exception { for (int i = 0; i < 10; i++) { System.out.println(newGuid()); } } } ===================================================另外一种方法: public static String generate(){ String uuid = UUID.randomUUID().toString().trim().replaceAll("-", ""); return uuid; }