용량 계산

  public static String humanReadableByteCount(long bytes, boolean si) {

    int unit = si ? 1000 : 1024;

    

    if (bytes < unit) return bytes + " B";

    int exp = (int) (Math.log(bytes) / Math.log(unit));

    String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp-1) + (si ? "" : "i");

    return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);

  }