Map 按字母升序排序

    public static String concatSignString(Map<String, String> map) {
            Map<String, String> paramterMap = new HashMap<>();
            map.forEach((key, value) -> paramterMap.put(key, value));
            // 按照key升续排序，然后拼接参数
            Set<String> keySet = paramterMap.keySet();
            String[] keyArray = keySet.toArray(new String[keySet.size()]);
            Arrays.sort(keyArray);
            StringBuilder sb = new StringBuilder();

            for (String k : keyArray) {
                if (StringUtils.isEmpty(sb.toString())) {
                    sb.append("?");
                } else {
                    sb.append("&");
                }
                sb.append(k).append("=").append(map.get(k));
            }
                return sb.toString();
            }




    public static void main(String[] args) {
        HashMap<String, String> hashMap = new HashMap<>();
        hashMap.put("b","2");
        hashMap.put("a","1");
        hashMap.put("c","3");
        hashMap.put("f","4");
        hashMap.put("h","6");
        hashMap.put("g","5");
        hashMap.put("u","7");

        String s = concatSignString(hashMap);
        System.out.println(s);
    }