java GUID生成器产生随机GUID的方法

r囧r小猫 2021-07-25 02:58 495阅读 0赞

package test;
    
    import java.net.*;
    import java.util.*;
    
    import java.security.MessageDigest;
    import java.security.NoSuchAlgorithmException;
    import java.security.SecureRandom;
    
    /**
     * <p>描述: GUID生成器，参考了来自www.JavaExchange.com的RandomGUID</p>
     */
    public class GuidGenerator extends Object
    {
       private static Random myRand; //基本java随机对象
       private static SecureRandom mySecureRand; //安全随机对象
    
       private static String s_id; //ip地址字符串
    
       static
       {
          mySecureRand = new SecureRandom();
          //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
          long secureInitializer = mySecureRand.nextLong();
          myRand = new Random(secureInitializer);
    
          try
          {
             //获得当前主机的ip地址字符串
             s_id = InetAddress.getLocalHost().toString();
          }
          catch (UnknownHostException e)
          {
             e.printStackTrace();
          }
       }
    
       /**
        * 缺省构造器
        */
       public GuidGenerator()
       {
       }
    
       /**
        * 缺省的产生随机GUID的方法
        * @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
        */
       public static String genRandomGUID()
       {
          return genRandomGUID(false);
       }
    
       /**
        * 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
        * @param secure true  : 带安全选项，用安全随机数对象生成
        *               false : 不带安全选项，用基本随机数对象生成
        * @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
        */
       public static String genRandomGUID(boolean secure)
       {
          String valueBeforeMD5 = ""; //消息消化对象消化前的字符串
          String valueAfterMD5 = ""; //经消息消化对象消化后的GUID字符串
    
          MessageDigest md5 = null; //消息消化对象
          StringBuffer sbValueBeforeMD5 = new StringBuffer();
    
          try
          {
             md5 = MessageDigest.getInstance("MD5");
          }
          catch (NoSuchAlgorithmException e)
          {
             System.out.println("Error: " + e);
             return valueBeforeMD5;
          }
    
          long time = System.currentTimeMillis(); //获得系统时间
          long rand = 0; //随机数
    
          if (secure) //用安全随机对象获得随机数
          {
             rand = mySecureRand.nextLong();
          }
          else
          //用基本随机对象获得随机数
          {
             rand = myRand.nextLong();
          }
    
          //拼接组成GUID的各个信息
          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(); //消息消化对象进行消化动作，返回128bit
    
          String strTemp = "";
          for (int i = 0; i < array.length; i++)
          {
             strTemp = (Integer.toHexString(array[i] & 0XFF));
             if (strTemp.length() == 1)
             {
                valueAfterMD5 = valueAfterMD5 + "0" + strTemp;
             }
             else
             {
                valueAfterMD5 = valueAfterMD5 + strTemp;
             }
          }
          //GUID标准格式如：C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
          return valueAfterMD5.toUpperCase();
       }
    
       public static void main(String args[])
       {
          for (int i = 1; i < 10; i++)
          {
             System.out.println(Integer.toString(i) + " : " + genRandomGUID());
          }
       }
    }

运行结果

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