字節轉MB與Mb轉字節

/**
 * 字節轉成MB
 */
private BigDecimal fileSizeConversion(Long fileSize){
    DecimalFormat df = new DecimalFormat("#.00");
    String format = df.format((double) fileSize / 1048576);
    return new BigDecimal(format);
}

/**
 * MB轉字節
 */
private static Long fileSizeConversion(BigDecimal fileSize){
    Long size = null;
    size = fileSize.longValue() * 1024 * 1024;
    return size;
}