自定义id生成器

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@UtilityClass
public class HashUtil {
 
    /** The logger. */
    private static final Logger LOGGER = LoggerFactory.getLogger(HashUtil.class);
 
    private static final String baseDigits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    private static final int BASE = baseDigits.length();
    private static final char[] digitsChar = baseDigits.toCharArray();
    private static final int FAST_SIZE = 'z';//122
    private static final int[] digitsIndex = new int[FAST_SIZE + 1];

    static {
        for (int i = 0; i < FAST_SIZE; i++) {
            digitsIndex[i] = -1;
        }
        //把每个字符对应的位置放入数组
        for (int i = 0; i < BASE; i++) {
            digitsIndex[digitsChar[i]] = i;
        }
    }

    private static long decode(String s) {
        long result = 0L;
        long multiplier = 1;
        for (int pos = s.length() - 1; pos >= 0; pos--) {
            int index = getIndex(s, pos);
            result += (index * multiplier);
            multiplier <<= 6;
        }
        return result;
    }
 
    private static String base62(long number) {
        if (number < 0)
            LOGGER.error("Number(Base62) must be positive: " + number);
        if (number == 0)
            return "0";
        StringBuilder buf = new StringBuilder();
        while (number != 0) {
            buf.append(digitsChar[(int) (number % BASE)]);
//            buf.append(digitsChar[(int) (number & (BASE - 1))]);
            number /= BASE;
//            number >>>= 6;
        }
        return buf.reverse().toString();
    }

    /**
     *
     * @param number
     * @param shift
     * @return
     */
    private static String hex10To64(long number, int shift) {
        char[] buf = new char[64];
        int charPos = 64;
        int radix = 1 << shift;
        long mask = radix - 1;
        do {
            buf[--charPos] = digitsChar[(int)(number & mask)];
            number >>>= shift;
        } while (number != 0);
        return new String(buf, charPos, (64 - charPos));
    }

    public static String base62(long number, int length) {
        char[] buf = new char[length];
        do {
            buf[--length] = digitsChar[(int) (number % BASE)];
            number /= BASE;
        } while (number != 0);
        for (int i = 0; i < length; i++) buf[i] = '0';
        return new String(buf);
    }
 
    private static int getIndex(String s, int pos) {
        char c = s.charAt(pos);
        if (c > FAST_SIZE) {
            LOGGER.error("Unknow character for Base64: " + s);
        }
        int index = digitsIndex[c];
        if (index == -1) {
            LOGGER.error("Unknow character for Base64: " + s);
        }
        return index;
    }
}

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  /**
   * id generator for current project
   *
   * <p> ID format: 7 digits time prefix(until 2081), 5 digits random alpha number.
   * ID repetition probability per millisecond is 1/916,132,832
   *
   * @return 12 digits ID
   */
  public static String id() {
    return HashUtil.base62(System.currentTimeMillis(),7) + HashUtil.base62(System.nanoTime() & 0x1FFFFFFF,5);
  }