将通知从Java服务器推送到移动设备

Question

我需要将通知从java服务器推送到移动设备。 我尝试使用Firebase，但在我看来，它需要开发一个移动应用程序。 相反，我不想开发移动应用程序。 我在下面写了java服务器代码，我想（希望）收件人 我的notisifications设备只需安装Firebase移动应用程序并注册到我在Firebase上创建的项目，以便接收通知。 事实并非如此，因为如果没有编写合适的应用程序我无法检索用户令牌ID，我错了吗？

有些东西按照我描述的方式工作吗？

由于

public class TESTCLASS {

    // Method to send Notifications from server to client end.
    // AUTH_KEY_FCM obtained by the Firebase project creation

    public final static String AUTH_KEY_FCM = "AAAAmenHuaY:APA9....BSmNry7BWL";
    public final static String API_URL_FCM = "https://fcm.googleapis.com/fcm/send";
    public final static String USER_DEVICE_TOKEN  = "???????";

    private void sendAndroidNotification(String deviceToken) throws Exception {

        String authKey = AUTH_KEY_FCM; // You FCM AUTH key
        String FMCurl = API_URL_FCM;

        URL url = new URL(FMCurl);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        conn.setUseCaches(false);
        conn.setDoInput(true);
        conn.setDoOutput(true);

        conn.setRequestMethod("POST");
        conn.setRequestProperty("Authorization", "key=" + authKey);
        conn.setRequestProperty("Content-Type", "application/json");

        JSONObject obj = new JSONObject();
        JSONObject msgObject = new JSONObject();
        msgObject.put("body", "Hello First Test notification");
        msgObject.put("title", "FCM Notificatoin Title");       

        obj.put("to", deviceToken);
        obj.put("notification",msgObject);

        OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(obj.toString());
        wr.flush();
        wr.close();

        int responseCode = conn.getResponseCode();
        System.out.println("Response Code : " + responseCode);

        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
    }


    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        System.out.println("---- main");
           TESTCLASS obj = new TESTCLASS();
        try {           
            obj.sendAndroidNotification(USER_DEVICE_TOKEN);
        } catch (Exception ex) {
            System.out.println("---- " + ex.getMessage());
        }
    }

}