对json进行排序处理

private String getSortJson(JSONObject json) {
    Set<String> set = json.keySet();
    List<String> list = new ArrayList<>();
    list.addAll(set);
    Collections.sort(list);
    StringBuffer sb = new StringBuffer();
    for (String key : list) {
        sb.append(key).append("=").append(json.getString(key)).append("&");
    }
    sb.replace(sb.length() - 1, sb.length(), "");
    return sb.toString();
}