无法使用Volley发布JSON

Question

I've searched a lot but can't find out what's happening. I wrote many variations of this code and here is the most recent one.

Android code

private static void post(@NonNull String url,
                         @NonNull Context context,
                         @NonNull final JSONObject jsonRequest,
                         @NonNull final ServerConnectionAdapter serverConnectionAdapter){
    Log.d(TAG, "post: URL = " + url);
    RequestQueue queue = Volley.newRequestQueue(context);
    JsonObjectRequest postRequest = new JsonObjectRequest(
            Request.Method.POST,
            url,
            jsonRequest,
            serverConnectionAdapter,
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    serverConnectionAdapter.onErrorResponse(null, error);
                }
            }) {
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            Map<String, String> map = new HashMap<>();
            // map.put("user", json.toString());
            map.put("user", "{\"id\":-1,\"name\":\"Gustavo Araujo\"}");
            return map;
        }
    };

    queue.add(postRequest);
}

Server (Java) code

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    System.out.println("doPost");
    System.out.println("REQUEST: ");
    for (Map.Entry<String, String[]> e : request.getParameterMap().entrySet()){
        System.out.print("  ");
        System.out.println(e.getKey() + ": " + java.util.Arrays.toString(e.getValue()));
    }

    System.out.println("end");
}

doPost method output

doPost
REQUEST: 
end

I've been starring my screen for so long that I think I can't find where is the error. I did find many examples, with and without the getParams(). I tried both, and didn't change anything.

The ServerConnectionAdapter is an abstract class that I created to unify the response with the error listener. I am sure that it is not the problem because it does work flawlessly with the GETs that I have.

The String url also can't be wrong (otherwise the server wouldn't have been triggered.

The jsonRequest also isn't the problem because I already used null there and didn't change the results at all.

As I said, I've been starring this code for hours, all my assumptions may be completely wrong, that's why I'm asking for help.

Answer 1

The error photo you posted in comment in telling me that your request was successful, there isn't any issue from mobile side. The issue is from server side. Because when you are making the request it's going on server but your server is not returning any proper Json. It's returning nothing that's why you are getting that exception. Android request needs a Json in return but you are server is not returning that.

There is a possibility that the issue can be from app side and the cause for that is that maybe you are not sending the proper parameters to server. But as far as I can see, the main issue is from server side. Because all these exceptions are not handled on server side. Like when the parameters are wrong it should return a json with message telling you that the parameters are wrong.

Answer 2

I was doing it wrong. The way that I wrote the doPost method I was reaching the request parametes, like when you access http://localhost:8080/something?key=value what is not what I intend to do. I needed to read the body of the request. To do so, in Java, it should be as the code below:

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    // Get the body of the request
    BufferedReader reader = request.getReader();

    // Print each line
    String line;
    while ((line = reader.readLine()) != null){
        System.out.println(line);
    }
}

Thank you for Zohaib Hassan for trying to help.