Json，Java，解析（如何仅获取json的一部分

Question

I need to receive the "extract" part of the following Json: https://en.wikipedia.org/w/api.php?format=json&action=query&prop=extracts&exintro&explaintext&redirects=1&titles=turkey

With my current code i receive the whole Json and dont really know how to go on:

public class MainActivity extends AppCompatActivity {
private Button btnSendRequest;
private TextView tvText;
private RequestQueue mRequestQueue;
private StringRequest stringRequest;
private JsonObjectRequest jsonObjectRequest;
private String url = "https://de.wikipedia.org/w/api.php?format=json&action=query&prop=extracts&exintro&explaintext&redirects=1&titles=ilmenau";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btnSendRequest = (Button) findViewById(R.id.btnSendRequest);
    tvText = (TextView) findViewById(R.id.tvText);

    btnSendRequest.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //send request and print the response using volley library
            sendRequestAndPrintResponse();
        }
    });
}
private void sendRequestAndPrintResponse() {

    mRequestQueue = Volley.newRequestQueue(this);

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
            (Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            tvText.setText("Response : " + response.toString());
          //  Log.i(TAG,"Response : " + response.toString());
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

            tvText.setText("Error : " + error.toString());
            //Log.i(TAG,"Error : " + error.toString());
        }
    });
    mRequestQueue.add(jsonObjectRequest);
}

}

So currently I am getting the whole Json back, but I only need to get the "extract" part of the Json. Can anyone help me?

Answer 1

Try this

try {
    JSONObject jsonObject = new JSONObject(response.toString());
    Iterator < String > keys = jsonObject.keys();

    while (keys.hasNext()) {

        String key = keys.next();
        String value = jsonObject.getString(key);

        Log.v("key", key);
        Log.v("value", value);

        if (key.equals("query")) {
            JSONObject jsonObject1 = new JSONObject(jsonObject.getString(key));
            Iterator < String > keysinner = jsonObject1.keys();

            while (keysinner.hasNext()) {
                String key1 = keysinner.next();
                String value1 = jsonObject1.getString(key1);

                Log.e("key1", key1);
                Log.e("value1", value1);

                if (key1.equals("pages")) {
                    JSONObject jsonObject2 = new JSONObject(jsonObject1.getString(key1));
                    Iterator < String > keyPagenumber = jsonObject2.keys();

                    while (keyPagenumber.hasNext()) {

                        String keyPageNumber = keyPagenumber.next();
                        String valuePagenumber = jsonObject2.getString(keyPageNumber);

                        Log.e("Pages key   :", keyPageNumber);
                        Log.e("Pages value :", valuePagenumber);

                        if (key1.equals("pages")) {
                            JSONObject jsonObjectPages = new JSONObject(jsonObject2.getString(keyPageNumber));
                            Iterator < String > keyPages = jsonObjectPages.keys();

                            while (keyPages.hasNext()) {
                                String keyPageDetail = keyPages.next();
                                String valuePageDetail = jsonObjectPages.getString(keyPageDetail);

                                Log.e("PagesDetail key   :", keyPageDetail);
                                Log.e("PagesDetail value :", valuePageDetail);

                            }
                        }
                    }
                }
            }
        }
    }
} catch (Exception e) {
    e.printStackTrace();
}

OUTPUT

Answer 2

Use GSON library!

So let's say that you deduce the whole json content of your jsonObjectRequest as a string that i will name theWholeContentOfYourJsonObjectRequestAsAString

JsonParser parser = new JsonParser();
JsonElement jsonTree = parser.parse(theWholeContentOfYourJsonObjectRequestAsAString);
JsonObject jsonObject = jsonTree.getAsJsonObject();
JsonElement f1 = jsonObject.get("extract");

Answer 3

Something like

JSONObject pages = response.getJSONObject("query").getJSONObject("pages");
JSONObject firstPage = pages.getJSONObject(pages.names().get(0));
String extract = firstPage.getString("extract");

should work.

Answer 4

To extract a piece of JSON Object (another JSON Object, Integer, String etc.) you don't have to use any external libraries like GSON. You can manage it with the following code.

   JSONObject jObj = new JSONObject(response);                     
   String InterestString = jObj.getJSONObject("local").getString("interests");

Answer 5

private void sendRequestAndPrintResponse() {

    mRequestQueue = Volley.newRequestQueue(this);

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
            (Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    try {
                        JSONObject query = response.getJSONObject("query");
                        JSONObject pages = query.getJSONObject("pages");
                        JSONObject nos = pages.getJSONObject("11125639");
                        String extract = nos.getString("extract");
                        Log.e(TAG, "onResponse: " + extract);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                    tvText.setText("Error : " + error.toString());
                    //Log.i(TAG,"Error : " + error.toString());
                }
            });
    mRequestQueue.add(jsonObjectRequest);
}

modify your code add these lines like this you should get extract