How to send request Header is “Content-Type”:“application/json” when GET on Volley

Question

I try to use GET on Volley , but i need send request to application/json .

I take a look for some answers , i try to use jsonBody , but it

Answer 1

I try to use GET on Volley

The docs for the method you are calling says this

Constructor which defaults to GET if jsonRequest is null, POST otherwise

You can't GET with an HTTP JSON body. Maybe that's the error.

//I try to use this for send Header is application/json
jsonBody = new JSONObject("{\"type\":\"example\"}");

That's not the header, so pass in null here to do GET

new JsonObjectRequest(url, null,

And towards the end of your request, override a method to request JSON

        ... 

        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("TAG", error.getMessage(), error);
        }


    }) { // Notice no semi-colon here
        @Override 
        public Map<String, String> getHeaders() throws AuthFailureError { 
            Map<String, String> params = new HashMap<String, String>();                
            params.put("Content-Type", "application/json");
            return params; 
        } 
    };

Answer 2

@Override 
public Map<String, String> getHeaders() throws AuthFailureError { 
    Map<String, String> params = new HashMap<String, String>();                
    params.put("Content-Type", "application/json");
    return params; 
} 

Implementation in your's

public class MainActivity extends AppCompatActivity {

    String url = "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RequestQueue mQueue = Volley.newRequestQueue(getApplicationContext());

        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, jsonBody,
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d("TAG", response.toString());
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.e("TAG", error.getMessage(), error);
                }
            }) { //no semicolon or coma
            @Override 
            public Map<String, String> getHeaders() throws AuthFailureError { 
                Map<String, String> params = new HashMap<String, String>();                
                params.put("Content-Type", "application/json");
                return params; 
            } 
        };
        mQueue.add(jsonObjectRequest);
    }
}

Answer 3

In general for setting a custom header you need to override getHeaders and set the custom header manually. However, volley handles content type headers differently and getHeaders way does not always work.

So for your case you need to override getBodyContentType. So your code will look like

JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, jsonBody,new Response.Listener<JSONObject>() {

@Override
public void onResponse(JSONObject response) {
   Log.d("TAG", response.toString());
}, new Response.ErrorListener(){
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("TAG", error.getMessage(), error);
        }


    }){
         @Override
         public String getBodyContentType(){
              return "application/json";
         }
    };

Answer 4

Use String request instead of jsonrequest like this

            StringRequest loginMe = new StringRequest(Request.Method.GET, "http://114.35.246.42:2212/MobileApp/DEST_WebService.asmx/GetNews", new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {

                    System.out.println("LoginActivity -- onResponse --> " + response);

                    if (progressDialog != null) {

                        progressDialog.dismiss();

                    }

                    try {

                        JSONObject jsonObject = new JSONObject(response);

                    } catch (Exception e) {

                        CommonUtility.somethingWentWrongDialog(activity,
                                "LoginActivity -- onResponse-- Exception --> ".concat(e.getMessage()));

                    }
                }
            }, new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {

                    if (progressDialog != null) {

                        progressDialog.dismiss();

                    }

                    CommonUtility.somethingWentWrongDialog(activity,
                            "LoginActivity -- onErrorResponse --> ".concat(error.getMessage()));

                }
            }) {

                @Override
                protected Map<String, String> getParams() {

                    Map<String, String> params = new HashMap<>();


                    System.out.println("LoginActivity -- LoginParams --> " + params.toString());

                    return params;

                }
            };

            loginMe.setRetryPolicy(new DefaultRetryPolicy(60000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                    DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

            Volley.newRequestQueue(activity).add(loginMe);