@RequestMapping(value = "/userPreference",produces="application/json;charset=utf-8")
@ResponseBody
public String userPreference(HttpServletRequest request) {
    InputStreamReader reader = null;
    String json = "";
    try {
        request.setCharacterEncoding("UTF-8");
        reader = new InputStreamReader(request.getInputStream(), "UTF-8");
        char[] buff = new char[1024];
        int length = 0;
        while ((length = reader.read(buff)) != -1) {
            String x = new String(buff, 0, length);
            System.out.println(x);
            json = json + x;
        }
    }
    catch (IOException e) {
        e.printStackTrace();
    }


    JSONObject js = JSONObject.parseObject(json);
    System.out.println(js);
    String uid = js.getString("uid");

}