public static String humanReadableByteCountSI(long bytes) {
    if (-1000 < bytes && bytes < 1000) {
      return bytes + " B";
    }
    CharacterIterator ci = new StringCharacterIterator("KMGTPE");
    while (bytes <= -999_950 || bytes >= 999_950) {
      bytes /= 1000;
      ci.next();
    }
    return String.format("%.2f %cB", bytes / 1000.0, ci.current());
  }
Transfer bytes to human-readable string. Copy from <a
href="https://stackoverflow.com/a/3758880">stackoverflow</a>.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/utils/FileUtils.java