guid生成 java_怎样用java生成GUID与UUID

傷城~ 2022-11-02 06:04 227阅读 0赞

import java.util.UUID;

public class Test \{

public static void main(String\[\] args) \{

UUID uuid = UUID.randomUUID();

System.out.println (uuid);

\}编译运行输出：

07ca3dec-b674-41d0-af9e-9c37583b08bb

两种方式生成guid 与uuid

需要comm log 库

/\*\*

\* @author Administrator

\* TODO To change the template for this generated type comment go to

\* Window - Preferences - Java - Code Style - Code Templates

\*/

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 RandomGUID extends Object \{

protected final org.apache.commons.logging.Log logger = org.apache.commons.logging.LogFactory

.getLog(getClass());

public String valueBeforeMD5 = "";

public String valueAfterMD5 = "";

private static Random myRand;

private static SecureRandom mySecureRand;

private static String s\_id;

private static final int PAD\_BELOW = 0x10;

private static final int TWO\_BYTES = 0xFF;

/\*

\* Static block to take care of one time secureRandom seed.

\* It takes a few seconds to initialize SecureRandom. You might

\* want to consider removing this static block or replacing

\* it with a "time since first loaded" seed to reduce this time.

\* This block will run only once per JVM instance.

\*/

static \{

mySecureRand = new SecureRandom();

long secureInitializer = mySecureRand.nextLong();

myRand = new Random(secureInitializer);

try \{

s\_id = InetAddress.getLocalHost().toString();

\} catch (UnknownHostException e) \{

e.printStackTrace();

/\*

\* Default constructor. With no specification of security option,

\* this constructor defaults to lower security, high performance.

\*/

public RandomGUID() \{

getRandomGUID(false);

/\*

\* Constructor with security option. Setting secure true

\* enables each random number generated to be cryptographically

\* strong. Secure false defaults to the standard Random function seeded

\* with a single cryptographically strong random number.

\*/

public RandomGUID(boolean secure) \{

getRandomGUID(secure);

/\*

\* Method to generate the random GUID

\*/

private void getRandomGUID(boolean secure) \{

MessageDigest md5 = null;

StringBuffer sbValueBeforeMD5 = new StringBuffer(128);

try \{

md5 = MessageDigest.getInstance("MD5");

\} catch (NoSuchAlgorithmException e) \{

logger.error("Error: " + e);

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(32);

for (int j = 0; j < array.length; ++j) \{

int b = array\[j\] & TWO\_BYTES;

if (b < PAD\_BELOW)

sb.append('0');

sb.append(Integer.toHexString(b));

valueAfterMD5 = sb.toString();

\} catch (Exception e) \{

logger.error("Error:" + e);

/\*

\* Convert to the standard format for GUID

\* (Useful for SQL Server UniqueIdentifiers, etc.)

\* Example: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6

\*/

public String toString() \{

String raw = valueAfterMD5.toUpperCase();

StringBuffer sb = new StringBuffer(64);

sb.append(raw.substring(0, 8));

sb.append("-");

sb.append(raw.substring(8, 12));

sb.append("-");

sb.append(raw.substring(12, 16));

sb.append("-");

sb.append(raw.substring(16, 20));

sb.append("-");

sb.append(raw.substring(20));

return sb.toString();

// Demonstraton and self test of class

public static void main(String args\[\]) \{

for (int i=0; i< 100; i++) \{

RandomGUID myGUID = new RandomGUID();

System.out.println("Seeding String=" + myGUID.valueBeforeMD5);

System.out.println("rawGUID=" + myGUID.valueAfterMD5);

System.out.println("RandomGUID=" + myGUID.toString());

同样

UUID uuid = UUID.randomUUID();

System.out.println("\{"+uuid.toString()+"\}");

UUID是指在一台机器上生成的数字，它保证对在同一时空中的所有机器都是唯一的。通常平台会提供生成UUID的API。UUID按照开放软件基金会(OSF)制定的标准计算，用到了以太网卡地址、纳秒级时间、芯片ID码和许多可能的数字。由以下几部分的组合：当前日期和时间(UUID的第一个部分与时间有关，如果你在生成一个UUID之后，过几秒又生成一个UUID，则第一个部分不同，其余相同)，时钟序列，全局唯一的IEEE机器识别号(如果有网卡，从网卡获得，没有网卡以其他方式获得)，UUID的唯一缺陷在于生成的结果串会比较长。关于UUID这个标准使用最普遍的是微软的GUID(Globals Unique Identifiers)。

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2009-04-27 15:44

2 楼

azhqiang

2010-10-28

第一个方法，我是jdk1.6的，提示没有randomUUID()这个方法，这是怎么回事呢。

1 楼

owl520\_je

2009-07-31

真强悍，很多的时候需要一个唯一标识，guid应该时最佳的选择了！

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[18e900b8666ce6f233d25ec02f95ee59.png]: /images/20221024/3d07bd68c7a24148ae7b01e4c135fd7b.png
[72dd548719f0ace4d5f9bca64e1d7715.png]: /images/20221024/a547ad179666456d9ade1785f830db8f.png
[966903dea4bcb507358d5dcce8b912e5.gif]: /images/20221024/557ecabba52d47f5b27e5285f4629060.png