N秒后杀死Volley请求

Question

我使用的是Volley库。我有一个问题。我在N秒（30秒）后无法停止请求 这是来源

private void searchTrains() {
    RequestQueue queue = Volley.newRequestQueue(getActivity());
    GlobalParameters.pDialog = new TrainCustomLoader(getActivity());
    GlobalParameters.pDialog.show();
    GlobalParameters.pDialog.setCancelable(false);
    String url = TrainUrls.trains();



    UTF8VolleySupport sr = new UTF8VolleySupport(Request.Method.GET, url, new Response.Listener<String>() {
        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        @Override
        public void onResponse(final String response) {




        }


    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            error.printStackTrace();
            if (GlobalParameters.pDialog != null)
                GlobalParameters.pDialog.dismiss();


            NetworkResponse errorRes = error.networkResponse;
            String stringData = "";
            int statusCode = errorRes.statusCode;


            if (errorRes != null && errorRes.data != null) {
                try {
                    stringData = new String(errorRes.data, "UTF-8");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }
            Log.e("Error", stringData);

        }
    }) {
        @Override
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String, String> params = new HashMap<>();
            params.put("Accept", "application/json");
            params.put("Authorization", "Bearer" + " " + token);
            return params;
        }
    };
    sr.setRetryPolicy(new DefaultRetryPolicy(
            30000,
            DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
            DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));


    queue.add(sr);
}

正如我所说，我可以从服务器得到回复，但我不能在30秒后停止请求 我怎么能解决我的问题？