• 首先构造一个Map
    • 对Map进行Key的排序后，获取值，再拼装，再拼接appSecret，进行Md5加密，最后转成大写。代码如下：
    2.  * acquired sign.
    3.  *
    4.  * @param signKey sign key
    5.  * @return sign
    7. private static String generateSign(final String signKey, final Map<String, String> params) {
    8.     List<String> storedKeys = Arrays.stream(params.keySet()
    9.             .toArray(new String[]{}))
    10.             .sorted(Comparator.naturalOrder())
    11.             .collect(Collectors.toList());
    12.             .filter(key -> !Objects.equals(key, Constants.SIGN))
    13.             .map(key -> String.join("", key, params.get(key)))
    14.             .collect(Collectors.joining()).trim()
    15.             .concat(signKey);
    16.     return DigestUtils.md5DigestAsHex(sign.getBytes()).toUpperCase();