怎么设置字体大小，这个字体太大

 /**
     * 字体变大为标准的n倍
     *
     * @param num 倍数
     * @return bytes for this command
     */
    @SuppressWarnings("unused")
    public static byte[] fontSizeSetBig(int num) {
        byte realSize = 0;
        switch (num) {
            case 0:
                realSize = 0;
                break;
            case 1:
                realSize = 17;