private static String random()

in linkis-engineconn-plugins/spark/src/main/java/org/apache/linkis/engineplugin/spark/executor/SecureRandomStringUtils.java [128:216]
78 lines of code
30 McCabe index (conditional complexity)

  private static String random(
      int count,
      int start,
      int end,
      final boolean letters,
      final boolean numbers,
      final char[] chars,
      final SecureRandom random) {
    if (count == 0) {
      return StringUtils.EMPTY;
    }
    if (count < 0) {
      throw new IllegalArgumentException(
          "Requested random string length " + count + " is less than 0.");
    }
    if (chars != null && chars.length == 0) {
      throw new IllegalArgumentException("The chars array must not be empty");
    }

    if (start == 0 && end == 0) {
      if (chars != null) {
        end = chars.length;
      } else if (!letters && !numbers) {
        end = Character.MAX_CODE_POINT;
      } else {
        end = 'z' + 1;
        start = ' ';
      }
    } else if (end <= start) {
      throw new IllegalArgumentException(
          "Parameter end (" + end + ") must be greater than start (" + start + ")");
    }

    final int zeroDigitAscii = 48;
    final int firstLetterAscii = 65;

    if (chars == null && (numbers && end <= zeroDigitAscii || letters && end <= firstLetterAscii)) {
      throw new IllegalArgumentException(
          "Parameter end ("
              + end
              + ") must be greater then ("
              + zeroDigitAscii
              + ") for generating digits "
              + "or greater then ("
              + firstLetterAscii
              + ") for generating letters.");
    }

    final StringBuilder builder = new StringBuilder(count);
    final int gap = end - start;

    while (count-- != 0) {
      final int codePoint;
      if (chars == null) {
        codePoint = random.nextInt(gap) + start;

        switch (Character.getType(codePoint)) {
          case Character.UNASSIGNED:
          case Character.PRIVATE_USE:
          case Character.SURROGATE:
            count++;
            continue;
        }

      } else {
        codePoint = chars[random.nextInt(gap) + start];
      }

      final int numberOfChars = Character.charCount(codePoint);
      if (count == 0 && numberOfChars > 1) {
        count++;
        continue;
      }

      if (letters && Character.isLetter(codePoint)
          || numbers && Character.isDigit(codePoint)
          || !letters && !numbers) {
        builder.appendCodePoint(codePoint);

        if (numberOfChars == 2) {
          count--;
        }

      } else {
        count++;
      }
    }
    return builder.toString();
  }