···
R.UU64()
···
好像是22位的

如果去掉UUID.randomUUID()的中横线，应该可以再短一些

找了一个19位的uuid代码，贴在下面

package com.my.util;

import java.io.PrintStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

public class ShortUUID
{
  static final char[] jdField_a_of_type_ArrayOfChar = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
  static final Map<Character, Integer> jdField_a_of_type_JavaUtilMap = new HashMap();
  private static final int jdField_a_of_type_Int = jdField_a_of_type_ArrayOfChar.length;
  
  public static void main(String[] paramArrayOfString)
  {
    long l = 0L;
    HashSet localHashSet = new HashSet();
    for (;;)
    {
      l += 1L;
      System.out.println(l);
      String str = generate();
      if (localHashSet.contains(str))
      {
        System.out.println(": " + str);
        break;
      }
      localHashSet.add(str);
    }
  }
  
  private static String a(long paramLong, int paramInt)
  {
    if ((paramInt < 2) || (paramInt > jdField_a_of_type_Int)) {
      paramInt = 10;
    }
    if (paramInt == 10) {
      return Long.toString(paramLong);
    }
    int i = 64;
    char[] arrayOfChar = new char[65];
    int j = paramLong < 0L ? 1 : 0;
    if (j == 0) {}
    for (paramLong = -paramLong; paramLong <= -paramInt; paramLong /= paramInt) {
      arrayOfChar[(i--)] = jdField_a_of_type_ArrayOfChar[((int)-(paramLong % paramInt))];
    }
    arrayOfChar[i] = jdField_a_of_type_ArrayOfChar[((int)-paramLong)];
    if (j != 0) {
      arrayOfChar[(--i)] = '-';
    }
    return new String(arrayOfChar, i, 65 - i);
  }
  
  private static String b(long paramLong, int paramInt)
  {
    long l = 1L << paramInt * 4;
    return a(l | paramLong & l - 1L, jdField_a_of_type_Int).substring(1);
  }
  
  public static String generate()
  {
    UUID localUUID = UUID.randomUUID();
    StringBuilder localStringBuilder = new StringBuilder();
    localStringBuilder.append(b(localUUID.getMostSignificantBits() >> 32, 8));
    localStringBuilder.append(b(localUUID.getMostSignificantBits() >> 16, 4));
    localStringBuilder.append(b(localUUID.getMostSignificantBits(), 4));
    localStringBuilder.append(b(localUUID.getLeastSignificantBits() >> 48, 4));
    localStringBuilder.append(b(localUUID.getLeastSignificantBits(), 12));
    return localStringBuilder.toString();
  }
  
  static
  {
    for (int i = 0; i < jdField_a_of_type_ArrayOfChar.length; i++) {
      jdField_a_of_type_JavaUtilMap.put(Character.valueOf(jdField_a_of_type_ArrayOfChar[i]), Integer.valueOf(i));
    }
  }
}

兽总，可以添加到R类中

啥叫UU64不可逆版本