Android Volley Request with OAuth2 Authorization

Question

I need to call a REST API that simply updates the value of a field in the database. To do this, I use the following Volley request, but it return an Unexpected response code 401 (unauthorized), it seems as if the headers for OAuth2 authorization get ignored. I checked the access token value and it is there correctly. What's my mistake?

private void sendRegistrationTokenToServer(final String token) {
         // user ID taken from SharedPreferences
         final String id = Integer.toString(SharedPrefManager.getInstance(this).getUserId());

         StringRequest stringRequest = new StringRequest
            (
             Request.Method.PUT,
             Constants.URL_GCM_TOKEN+"/"+ Utils.base64Encode(id),

             new Response.Listener<String>()
                {
                 @Override
                 public void onResponse(String s)
                    {
                     Intent registrationComplete = new Intent(REGISTRATION_TOKEN_SENT);
                     LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(registrationComplete);
                    }
                },

             new Response.ErrorListener()
                {
                 @Override
                 public void onErrorResponse(VolleyError volleyError)
                    {
                     Toast.makeText(getBaseContext(), "Unexpected error occurred when saving the GCM token for push notifications", Toast.LENGTH_LONG).show();
                    }
                })
            {
             @Override
             protected Map<String, String> getParams() throws AuthFailureError
                {
                 Map<String, String> params = new HashMap<>();

                 params.put("gcm_token", token);

                 return params;
                }


             @Override
             public Map<String, String> getHeaders() throws AuthFailureError
                {
                 Map<String, String> headers = new HashMap<String, String>();

                 headers.put("Content-Type", "application/json");

                 String bearer = "Bearer ".concat(SharedPrefManager.getInstance(getBaseContext()).getUserAccessToken());

                 headers.put("Authorization", bearer);

                 return headers;
                }
            };

         App.getInstance().addToRequestQueue(stringRequest);
        }

Answer 1

I answer myself, in case someone needed to know the solution :) For some motivation, the server policy removes the Authorization header, so I had to provide a different custom header, named X-Authorization-Copy , with the same values as the Authorization one (" Bearer "), and I had to modify the server code in order to manage the case where the Authorization header is not found in the request. So the server checks if the other custom X-Authorization-Copy header is present and it takes authorization data from it. Further, the Content-Type header must be x-www-form-urlencoded, instead of application/json, otherwise it will give an error. Now it works.