文件字节大小显示成M,G和K

//字节大小，K,M,G
public static final long KB = 1024;
public static final long MB = KB * 1024;
public static final long GB = MB * 1024;  

/**
 * 文件字节大小显示成M,G和K
 * @param size
 * @return
 */
public static String displayFileSize(long size) {
    if (size >= GB) {
        return String.format("%.1f GB", (float) size / GB);
    } else if (size >= MB) {
        float value = (float) size / MB;
        return String.format(value > 100 ? "%.0f MB" : "%.1f MB", value);
    } else if (size >= KB) {
        float value = (float) size / KB;
        return String.format(value > 100 ? "%.0f KB" : "%.1f KB", value);
    } else {
        return String.format("%d B", size);
    }
}