轉自：https://www.cnblogs.com/jiyanle/p/5161533.html

/**
 * 返回擷取指定長度位元組數後的字串,多餘部分用“...”代替
 * 
 * @作者 jiyanle
 * @日期 2014-7-6
 * @param strs
 * @param length
 * @return
 */
public static String cutStr(String strs, int length) {
    int sum = 0;
    String finalStr = "";
    if (null == strs || strs.getBytes().length <= length) {
        finalStr = (strs==null?"":strs);
    } else {
        for (int i = 0; i < strs.length(); i++) {
            String str = strs.substring(i, i + 1);
            // 累加單個字元位元組數
            sum += str.getBytes().length;
            if (sum > length) {
                finalStr = strs.substring(0, i) + "...";
                break;
            }
        }
    }
    return finalStr;
}