convert byte count to human readable

FileUtil.java

    /**
     *                          SI         BINARY
     * 0:                       0 B        0 B
     * 27:                      27 B       27 B
     * 999:                     999 B      999 B
     * 1000:                    1.0 kB     1000 B
     * 1023:                    1.0 kB     1023 B
     * 1024:                    1.0 kB     1.0 KiB
     * 1728:                    1.7 kB     1.7 KiB
     * 110592:                  110.6 kB   108.0 KiB
     * 7077888:                 7.1 MB     6.8 MiB
     * 452984832:               453.0 MB   432.0 MiB
     * 28991029248:             29.0 GB    27.0 GiB
     * 1855425871872:           1.9 TB     1.7 TiB
     * 9223372036854775807:     9.2 EB     8.0 EiB   (Long.MAX_VALUE)
     *
     * @param bytes
     * @param si
     * @return
     */
    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);
    }