无法从Android应用中的服务器获取JSON数据

Question

So I have just started playing around with JSON and Volley. I've created a server using XAMMP and added the php script required to generate JSON data. It comes up fine in the browser. However, when running the app on the emulator. The data is never retrieved and the progress dialog endlessly loads, so the app never crashes. The code I've adopted is below. What am I missing?

public class Config {


public static final String DATA_URL2= "http://10.0.2.2:8080/webservice/index.php";
public static final String KEY_ID = "ID";
public static final String KEY_NAME = "Name";
public static final String KEY_SURNAME = "Surname";
public static final String JSON_ARRAY = "result";}

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private EditText editTextId;
private Button buttonGet;
private TextView textViewResult;

private ProgressDialog loading;

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

    editTextId = (EditText) findViewById(R.id.editTextId);
    buttonGet = (Button) findViewById(R.id.buttonGet);
    textViewResult = (TextView) findViewById(R.id.textViewResult);

    buttonGet.setOnClickListener(this);
}

private void getData() {

    loading = ProgressDialog.show(this,"Please wait...","Fetching...",false,false);

    String url = Config.DATA_URL2.toString();

    StringRequest stringRequest = new StringRequest(url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            loading.dismiss();
            showJSON(response);
        }
    },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
}

private void showJSON(String response){
    String id="";
    String name="";
    String surname = "";
    try {
        JSONObject jsonObject = new JSONObject(response);
        JSONArray result = jsonObject.getJSONArray(Config.JSON_ARRAY);
        JSONObject collegeData = result.getJSONObject(0);
        id = collegeData.getString(Config.KEY_ID);
        name = collegeData.getString(Config.KEY_NAME);
        surname = collegeData.getString(Config.KEY_SURNAME);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    textViewResult.setText("ID:\t"+id+"\nName:\t" +name+ "\nSurname:\t"+ surname);
}

@Override
public void onClick(View v) {
    getData();
}}

Here is my stack trace:

    02-14 00:15:19.215 22098-22098/? I/art: Not late-enabling -Xcheck:jni (already on)
02-14 00:15:19.807 22098-22125/za.co.volleydemo D/OpenGLRenderer: Render dirty regions requested: true
02-14 00:15:19.839 22098-22098/za.co.volleydemo D/Atlas: Validating map...
02-14 00:15:19.902 22098-22106/za.co.volleydemo I/art: Background partial concurrent mark sweep GC freed 1945(127KB) AllocSpace objects, 0(0B) LOS objects, 52% free, 921KB/1945KB, paused 5.021ms total 25.227ms
02-14 00:15:19.958 22098-22125/za.co.volleydemo I/OpenGLRenderer: Initialized EGL, version 1.4
02-14 00:15:20.046 22098-22125/za.co.volleydemo D/OpenGLRenderer: Enabling debug mode 0
02-14 00:15:20.073 22098-22125/za.co.volleydemo W/EGL_emulation: eglSurfaceAttrib not implemented
02-14 00:15:20.073 22098-22125/za.co.volleydemo W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xae2c5a40, error=EGL_SUCCESS
02-14 00:15:23.058 22098-22182/za.co.volleydemo E/Volley: [275] BasicNetwork.performRequest: Unexpected response code 401 for http://10.0.2.2:8080
02-14 00:15:23.076 22098-22125/za.co.volleydemo W/EGL_emulation: eglSurfaceAttrib not implemented
02-14 00:15:23.077 22098-22125/za.co.volleydemo W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xa609f700, error=EGL_SUCCESS
02-14 00:15:23.220 22098-22182/za.co.volleydemo E/Volley: [275] BasicNetwork.performRequest: Unexpected response code 401 for http://10.0.2.2:8080

Additionally... here is my php script

<?php

define('HOST','localhost');
  define('USER','ruchen');
  define('PASS','lollatjie');
  define('DB','webservice1');

 $con = mysqli_connect(HOST,USER,PASS,DB);

$sql = "select * from users where surname = 'Miller'";

$res = mysqli_query($con,$sql);

$result = array();

while($row = mysqli_fetch_array($res)){
array_push($result,
array('id'=>$row[0],
'name'=>$row[1],
'surname'=>$row[2]
));
}

echo json_encode(array("result"=>$result));

mysqli_close($con);
?>

and finally, the JSON data generated by the script through my internet browser...

{"result":[{"id":"7","name":"Bob","surname":"Miller"}]}

Answer 1

401 means you are not authorized to this url.

From this link http codes

10.4.2 401 Unauthorized

The request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.47) containing a challenge applicable to the requested resource. The client MAY repeat the request with a suitable Authorization header field (section 14.8). If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials

Answer 2

I'm not sure why you get Error Code 401, but I notice something strange in your code. Why are you making a String request and not a JsonObject request?!

You are getting JSON data from your php service after all?

Change it to a JsonObjectRequest as the beginning of your Json is an Object called "result" which holds an array.

I do the same thing in my app and my Volley download looks like that:

 theEvents = new ArrayList<Event>();
    requestQueue = Volley.newRequestQueue(getActivity());
    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
            (Request.Method.GET, urlService, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {

                    try {


                        id = response.getString(Config.KEY_ID); // response is now the actual object called "result" from your JSON data.
                          // do something with the ID
                        }
.........etc