Android Volley - can't do a JSON request with POST, getting empty response

问题

I am trying to make a json request using Volley library to a php server, but for some reason the server does not receive the json object I am sending, and it responds with empty string. Here is my code

import android.content.Context;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response.Listener;
import com.android.volley.Response.ErrorListener;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;

public class MyVolley implements  Listener, ErrorListener {

    private static Context appContext;

    public MyVolley(Context context) {
        appContext = context;
    }

    public void stuff() throws JSONException {
        RequestQueue queue = Volley.newRequestQueue(appContext);
        JSONObject obj = new JSONObject();
        obj.put("param1", "assda");
        obj.put("param2", "fassfafsa");
        JsonObjectRequest stringRequest = new JsonObjectRequest(Request.Method.POST, "some url here", obj, this, this);
        queue.add(stringRequest);
    }

    @Override
    public void onResponse(Object response) {
        System.out.println(response);
    }

    @Override
    public void onErrorResponse(VolleyError error) {
        System.out.println(error);
    }
}

And when it executes, this is what the server receives

array (
  'Content-Type' => 'application/json; charset=utf-8',
  'User-Agent' => 'pointless info here',
  'Host' => 'some host here',
  'Connection' => 'Keep-Alive',
  'Accept-Encoding' => 'gzip',
  'Content-Length' => '107',
) array (
) array (
)

Why could that be happening?

回答1:

Make sure it's not a server side error (try your service using Postman for instance).

I personally faced the same issue some time ago, changing JsonObjectRequest to StringRequest fixed my problem.

Take a look at this link : https://stackoverflow.com/a/31613565/7871886

Now I use Retrofit2 instead of Volley... Could be an option. Happy coding

回答2:

Not sure what was your problem, but for the future googlers:

My problem was that I was trying to read form $_POST instead of php://input

Full code (working):

Java:

JSONObject jsonobj; // declared locally so that it destroys after serving its purpose
jsonobj = new JSONObject();
try {
    // adding some keys
    jsonobj.put("new key", Math.random());
    jsonobj.put("weburl", "hashincludetechnology.com");
    // lets add some headers (nested JSON object)
    JSONObject header = new JSONObject();
    header.put("devicemodel", android.os.Build.MODEL); // Device model
    header.put("deviceVersion", android.os.Build.VERSION.RELEASE); // Device OS version
    header.put("language", Locale.getDefault().getISO3Language()); // Language
    jsonobj.put("header", header);
    // Display the contents of the JSON objects
    display.setText(jsonobj.toString(2));
} catch (JSONException ex) {
    display.setText("Error Occurred while building JSON");
    ex.printStackTrace();
}

JsonObjectRequest jsObjRequest = new JsonObjectRequest(Request.Method.POST, URL, jsonobj, new Response.Listener<JSONObject>() {


    @Override
    public void onResponse(JSONObject response) {
        System.out.println("onResponse()");

        try {
            result.setText("Response: " + response.toString(2))

            System.out.println("Response: " + response.toString(2));
        } catch (JSONException e) {
            display.setText("Error Occurred while building JSON");
            e.printStackTrace();
        }
        //to make sure it works backwards as well

    }
}, new Response.ErrorListener() {

    @Override
    public void onErrorResponse(VolleyError error) {
        System.out.println("onErrorResponse()");
        System.out.println(error.toString());


    }
});


System.out.println("After the request is made");
// Add the request to the RequestQueue.
queue.add(jsObjRequest);

Clarification: display and result are two TextView objects I am using to display data on the screen, and queue is Volley's request queue.

PHP:

$inp = json_decode(file_get_contents('php://input')); //$input now contains the jsonobj
echo json_encode(["foo"=>"bar","input"=>$inp]); //to make sure we received the json and to test the response handling

Your Android Monitor should output sth. like :

{
    "foo":"bar",
    "input":{
        "new key":0.8523024722406781,
        "weburl":"hashincludetechnology.com",
        "header": {
            "devicemodel":"Android SDK built for x86",
            "deviceVersion":"7.1",
            "language":"eng"
        }
    }
}

来源：https://stackoverflow.com/questions/43498114/android-volley-cant-do-a-json-request-with-post-getting-empty-response