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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.io.*;
  4. import java.lang.reflect.*;
  5. import java.net.*;
  6. import java.nio.*;
  7. import java.text.*;
  8. import java.util.*;
  9.  
  10. class Ideone
  11. {
  12. 	public static void main (String[] args) throws java.lang.Exception
  13.     {
  14.     	String idStr = "4f5e73f72bb2492b9ffa7b12d55111f3";
  15.         System.out.println("Converting Guid string: " + idStr);
  16.  
  17.         UUID idUuid = fromGuidString(idStr);
  18.         System.out.println("To UUID: " + idUuid);
  19.  
  20.         String idStr2 = toGuidString(idUuid);
  21.         System.out.println("Back to string: " + idStr2);
  22.     }
  23.  
  24.     public static void reverse(byte[] bytes) {
  25.         if (bytes == null)
  26.             return;
  27.  
  28.         int i = 0;
  29.         int j = bytes.length - 1;
  30.         byte hold;
  31.         while (j > i) {
  32.             hold = bytes[j];
  33.             bytes[j] = bytes[i];
  34.             bytes[i] = hold;
  35.             j--;
  36.             i++;
  37.         }
  38.     }
  39.  
  40.     final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
  41.  
  42.     public static String toHex(byte[] bytes) {
  43.         char[] hexChars = new char[bytes.length * 2];
  44.         for ( int j = 0; j < bytes.length; j++ ) {
  45.             int v = bytes[j] & 0xFF;
  46.             hexChars[j * 2] = hexArray[v >>> 4];
  47.             hexChars[j * 2 + 1] = hexArray[v & 0x0F];
  48.         }
  49.         return new String(hexChars);
  50.     }
  51.  
  52.     public static byte[] fromHex(String hex) {
  53.         int len = hex.length();
  54.         byte[] data = new byte[len / 2];
  55.         for (int i = 0; i < len; i += 2) {
  56.             data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
  57.                         + Character.digit(hex.charAt(i+1), 16));
  58.         }
  59.         return data;
  60.     }
  61.  
  62.     public static String toGuidString(UUID uuid) {
  63.         byte[] guidBytes = toGuidBytes(uuid);
  64.         String to = toHex(guidBytes);
  65.         return to;
  66.     }
  67.  
  68.     public static UUID fromGuidString(String guid) {
  69.         guid = guid.replaceAll("-","");
  70.         byte[] guidBytes = fromHex(guid);
  71.         UUID to = fromGuidBytes(guidBytes);
  72.         return to;
  73.     }
  74.  
  75.     public static UUID fromGuidBytes(byte[] guidBytes) {
  76.         ByteBuffer buf = ByteBuffer.wrap(guidBytes);
  77.  
  78.         byte[] first4 = new byte[4];
  79.         buf.get(first4);
  80.         reverse(first4);
  81.  
  82.         byte[] second2 = new byte[2];
  83.         buf.get(second2);
  84.         reverse(second2);
  85.  
  86.         byte[] third2 = new byte[2];
  87.         buf.get(third2);
  88.         reverse(third2);
  89.  
  90.         long lsb = buf.getLong();
  91.  
  92.         buf = ByteBuffer.wrap(new byte[8])
  93.             .put(first4)
  94.             .put(second2)
  95.             .put(third2);
  96.  
  97.         buf.rewind();
  98.         long msb = buf.getLong();
  99.  
  100.         return new UUID(msb, lsb);
  101.     }
  102.  
  103.     public static byte[] toGuidBytes(UUID theUuid) {
  104.         ByteBuffer first8 = ByteBuffer.allocate(8);
  105.         first8.putLong(theUuid.getMostSignificantBits());
  106.         first8.rewind();
  107.  
  108.         byte[] first4 = new byte[4];
  109.         first8.get(first4);
  110.         reverse(first4);
  111.  
  112.         byte[] second2 = new byte[2];
  113.         first8.get(second2);
  114.         reverse(second2);
  115.  
  116.         byte[] third2 = new byte[2];
  117.         first8.get(third2);
  118.         reverse(third2);
  119.  
  120.         ByteBuffer converted16 = ByteBuffer.allocate(16)
  121.             .put(first4)
  122.             .put(second2)
  123.             .put(third2);
  124.  
  125.         ByteBuffer last8 = ByteBuffer.allocate(8);
  126.         last8.putLong(theUuid.getLeastSignificantBits());
  127.         last8.rewind();
  128.  
  129.         converted16.put(last8);
  130.  
  131.         return converted16.array();
  132.     }
  133. }
Success #stdin #stdout 0.11s 320512KB
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Standard input is empty
stdout
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Converting Guid string: 4f5e73f72bb2492b9ffa7b12d55111f3
To UUID: f7735e4f-b22b-2b49-9ffa-7b12d55111f3
Back to string: 4F5E73F72BB2492B9FFA7B12D55111F3
https://ideone.com/mk5H4V
ServiceStack UUID/Guid Serialization
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
secret

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