Volley JsonObjectRequest send headers in GET Request

问题

I am trying to send some authentication headers from GET request and I tried using Volley JsonObjectRequest call :

Map<String,String> params=new HashMap<String,String>();
        params.put("token","fghjbvjhnjjk");
        activity.showDialog();
        JsonObjectRequest req = new JsonObjectRequest(Request.Method.GET,url,
                new JSONObject(params), new Response.Listener<JSONObject>() {

            @Override
            public void onResponse(JSONObject response) {
                Log.d(tag, response.toString());
                activity.hideDialog();
                try {
                    activity.onRequestServed(response, code);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d(tag, "Error: " + error.getMessage());
                Log.e(tag, "Site Info Error: " + error.getMessage());
                Toast.makeText(activity.getApplicationContext(),
                        error.getMessage(), Toast.LENGTH_SHORT).show();
                activity.hideDialog();
                try {
                    activity.onRequestServed(null,code);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });
        req.setShouldCache(true);

But its showing:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference
        at com.android.volley.Request.<init>(Request.java:136)
        at com.android.volley.toolbox.JsonRequest.<init>(JsonRequest.java:58)
        at com.android.volley.toolbox.JsonObjectRequest.<init>(JsonObjectRequest.java:47)

I read somewhere that you can pass headers by making a hashmap and thus create a new JsonObject with that parameter. Maybe that will work on a POST request. Please help..

回答1:

Well, the thing is simple and very precise. Passing headers to either GET or POST request, you need to override getHeaders method in JsonObjectRequest Class. This is how it will be done:

JsonObjectRequest req = new JsonObjectRequest(Request.Method.GET,url,
                null, new Response.Listener<JSONObject>() {

            @Override
            public void onResponse(JSONObject response) {
                Log.d(tag, response.toString());
                activity.hideDialog();
                try {
                    activity.onRequestServed(response, code);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d(tag, "Error: " + error.getMessage());
                Log.e(tag, "Site Info Error: " + error.getMessage());
                Toast.makeText(activity.getApplicationContext(),
                        error.getMessage(), Toast.LENGTH_SHORT).show();
                activity.hideDialog();
                try {
                    activity.onRequestServed(null,code);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }) {

            /**
             * Passing some request headers
             */
            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                HashMap<String, String> headers = new HashMap<String, String>();
                //headers.put("Content-Type", "application/json");
                headers.put("key", "Value");
                return headers;
            }
        };

回答2:

I got the same problem but I solved it by double check on URL make sure it's is correct Like : http://192.168.123.102:8080/xxx/xxx

来源：https://stackoverflow.com/questions/35218464/volley-jsonobjectrequest-send-headers-in-get-request