java中字符串如何计算字节长度

        //编码格式有 UTF-8 GB2312 GBK UTF-16 UTF-32
        try {
            int length = "测试不同编码格式的字节长度".getBytes("编码格式").length;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

    public static String getLenString(String content, int len) {
        if (content == null || content.length() == 0) {
            return content;
        }
        byte[] bytes = content.getBytes();
        if (bytes.length > len) {
            int tempLen = new String(bytes, 0, len).length();
            content = content.substring(0, tempLen);
            // 防止最后一个字符的长度不是一个字节数
            if (content.getBytes().length > len) {
                content = content.substring(0, tempLen - 1);
            }
        }
        return content;
    }