/**
     * 以byte为单位截取定长的String，用于显示的美观，超过定长部分用..代替
     * @param String str 将被截取的源字符串
     * @param int byteLength 以byte为单位的字符串长度
     * @param boolean isFillNeeded 源字符串长度不够时，是否需要填充空格
     */
    public static String truncateString(String str, int byteLength, boolean isFillNeeded) {
        try {
            if (str.getBytes().length < byteLength) {
                if (isFillNeeded) {
                    int spaceNeeded = byteLength - str.getBytes().length;
                    StringBuffer sb = new StringBuffer(byteLength);
                    sb.append(str);
                    for (int i = 0; i < spaceNeeded; i++) {
                        sb.append(" ");
                    }
                    return sb.toString();
                } else {
                    return str;
                }
            } else {
                while (str.getBytes().length > (byteLength - 2)) {
                    str = str.substring(0, str.length() - 1);
                }

                int spaceNeeded = byteLength - 2 - str.getBytes().length;
                StringBuffer sb = new StringBuffer(byteLength);
                sb.append(str).append("..");
                for (int i = 0; i < spaceNeeded; i++) {
                    sb.append(" ");
                }
                return sb.toString();
            }
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }