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Números radomicos MD5
public class RandomGUID extends Object {
private static Random random;
private static SecureRandom secureRandom;
private static String secureId;
/*
* <pre></b>Bloco estatico para cuidar do tempo de uma parte secureRandom. Este bloco
* sera executado apenas uma vez por instancia de JVM.</b></pre>
*/
static {
secureRandom = new SecureRandom();
long secureInitializer = secureRandom.nextLong();
random = new Random(secureInitializer);
try {
secureId = InetAddress.getLocalHost().toString();
} catch (UnknownHostException e) {
e.getMessage();
}
}
/*
* <pre><b>Metodo para gerar o GUID aleatorio para converter para o formato padrao
* para GUID (Util para UniqueIdentifiers de bancos de dados, etc...)
* Exemplo: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6. Definir secure = true:
* verdadeiro permite que cada numero aleatorio gerado seja criptografado.
* Definir secure = false(Default) permite o numero aleatorio padrao seja
* cripatografado.</b></pre>
*/
private static String getRandomGUID(boolean secure) throws NoSuchAlgorithmException {
MessageDigest md5 = null;
StringBuilder sbValueBeforeMD5 = new StringBuilder();
md5 = MessageDigest.getInstance("MD5");
long time = System.currentTimeMillis();
long rand = 0;
if (secure) {
rand = secureRandom.nextLong();
} else {
rand = random.nextLong();
}
sbValueBeforeMD5.append(secureId);
sbValueBeforeMD5.append(":");
sbValueBeforeMD5.append(Long.toString(time));
sbValueBeforeMD5.append(":");
sbValueBeforeMD5.append(Long.toString(rand));
String valueBeforeMD5 = sbValueBeforeMD5.toString();
md5.update(valueBeforeMD5.getBytes());
byte[] array = md5.digest();
StringBuilder sb = new StringBuilder();
for (int j = 0; j < array.length; ++j) {
int b = array[j] & 0xFF;
if (b < 0x10) {
sb.append('0');
}
sb.append(Integer.toHexString(b));
}
return sb.toString();
}
/**
* <b>Este método retorna um GUID com 32 caracteres formatados.</b>
*
* @return String
* @throws java.security.NoSuchAlgorithmException
*/
public static String get() throws NoSuchAlgorithmException {
String randomGuid = getRandomGUID(false).toUpperCase();
StringBuilder sb = new StringBuilder();
sb.append(randomGuid.substring(0, 8));
sb.append("-");
sb.append(randomGuid.substring(8, 12));
sb.append("-");
sb.append(randomGuid.substring(12, 16));
sb.append("-");
sb.append(randomGuid.substring(16, 20));
sb.append("-");
sb.append(randomGuid.substring(20));
return sb.toString();
}
public static void main(String args[]) throws NoSuchAlgorithmException {
System.out.println(get());
}
}
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