SpringBoot 文件大写转换

将文件大小（字节），达到KB的转成KB,达到M的转成M

    /**
     * 方法一
     * @param size
     * @return
     */
    public static String toSize(long size) {
        if (size <= 0) {
            return "0";
        }
        final String[] units = new String[]{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB"};
        int digitGroups = (int) (Math.log10(size) / Math.log10(1024));
        return new DecimalFormat("#,###.##").format(size / Math.pow(1024, digitGroups)) + " " + units[digitGroups];
    }
	
    /**
     * 方法二
     * @param size
     * @return
     */
    // 定义单位常量
    private static final long KB = 1024L;
    private static final long MB = KB * 1024L;
    private static final long GB = MB * 1024L;
    private static final long TB = GB * 1024L;

    public static String readableFileSize(long bytes) {
        if (bytes >= TB) {
            return String.format("%.2f TB", (double) bytes / TB);
        } else if (bytes >= GB) {
            return String.format("%.2f GB", (double) bytes / GB);
        } else if (bytes >= MB) {
            return String.format("%.2f MB", (double) bytes / MB);
        } else if (bytes >= KB) {
            return String.format("%.2f KB", (double) bytes / KB);
        } else {
            return String.format("%d B", bytes);
        }
    }