无法使用 volley 将 JSON 数据发布到 URL：响应代码 400

如何解决无法使用 volley 将 JSON 数据发布到 URL：响应代码 400

我正在尝试将“JSON”数据发布到 String URL DOWNLINK_URL = "https://integrations.thethingsnetwork.org/ttn-us-west/api/v2/down/testing/newbee_testing?key=MY_APP_KEY";

我不确定我的代码有什么问题，我不断收到 Volley: [2500] NetworkUtility.shouldRetryException: Unexpected response code 400 for DOWNLINK_URL

如果您发现我的代码有任何错误或有任何建议，请在下方评论。

先谢谢你！

private void postDataUsingVolley(String dev_id,String payload_raw) {

    try {
        RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());
        JSONObject params = new JSONObject();

        params.put("dev_id",dev_id);
        params.put("port","1");
        params.put("confirmed","false");
        params.put("payload_raw",payload_raw);
        params.put("schedule","replace");

        final String mRequestBody = params.toString();

        StringRequest stringRequest = new StringRequest(Request.Method.POST,DOWNLINK_URL,new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                Log.i("LOG_VOLLEY",response);
            }
        },new Response.ErrorListener() {
            /* import com.android.volley.toolBox.HttpHeaderParser; */
            public void onErrorResponse(VolleyError error) {

                // As of f605da3 the following should work
                NetworkResponse response = error.networkResponse;
                if (error instanceof ServerError && response != null) {
                    try {
                        String res = new String(response.data,HttpHeaderParser.parseCharset(response.headers,"utf-8"));
                        // Now you can use any deserializer to make sense of data
                        JSONObject obj = new JSONObject(res);
                    } catch (UnsupportedEncodingException e1) {
                        // Couldn't properly decode data to string
                        e1.printstacktrace();
                    } catch (JSONException e2) {
                        // returned data is not JSONObject?
                        e2.printstacktrace();
                    }
                }
            }
        }) {
            @Override
            public String getBodyContentType() {
                return "application/json; charset=utf-8";
            }

            @Override
            public Map<String,String> getHeaders() throws AuthFailureError {
                HashMap<String,String> headers = new HashMap<String,String>();
                headers.put("Content-Type","application/json; charset=utf-8");
                return headers;
            }

            @Override
            protected Response<String> parseNetworkResponse(NetworkResponse response) {
                String responseString = "";
                if (response != null) {

                    responseString = String.valueOf(response.statusCode);

                }
                return Response.success(responseString,HttpHeaderParser.parseCacheHeaders(response));
            }
        };

        requestQueue.add(stringRequest);
    } catch (JSONException e) {
        e.printstacktrace();
    }
}