Android JSON解析器加载更多数据

Question

Because my json source is sometimes too long, and my android app crashes if it takes too long to load, i want to modify my code, so that when the user scrolls down to automaticaly load data or if is more simple, i would ike to add a button "Load More". Here is my existing code. What is the part i must modify for adding autoload or maybe a "Load More" button? Thanks!

package com.radioxxx.aacplay;

import android.app.DownloadManager;
import android.app.Fragment;
import android.app.ListFragment;
import android.app.ProgressDialog;
import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;
import android.widget.TextView;

import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class FazeNoi extends ListFragment {
    JSONParser2 jsonParser = new JSONParser2();


    private ProgressDialog pDialog;
    ArrayList<HashMap<String, String>> tracksList;

    JSONArray albums = null;

    String nume_piesa, cale;
    String titlu;

    private static final String URL_ALBUMS = "http://www.radioxxx.ro/json-news";
    private static final String TAG_TITLU = "Titlu";
    private static final String TAG_POZA = "FazeNoiID";
    private static final String TAG_NUME = "CMSdate";
    private static final String TAG_CALE = "URL";



    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        tracksList = new ArrayList<HashMap<String, String>>();

        new LoadTracks().execute();



    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_fazenoi, container, false);

        return rootView;
    }


    class LoadTracks extends AsyncTask<String, String, String> {


        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(getActivity());
            pDialog.setMessage("Se incarca ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        protected String doInBackground(String... args) {
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            //params.add(new BasicNameValuePair(TAG_ID, album_id));

            String json = jsonParser.makeHttpRequest(URL_ALBUMS, "GET",
                    params);

            Log.d("Track List JSON: ", json);

            try {
                JSONArray albums = new JSONArray(json);



                for (int i = 0; i < albums.length(); i++) {
                    JSONObject c = albums.getJSONObject(i);
                    //String poza = c.getJSONArray("PozaPrincipalaMedia").getJSONObject(0).getString("thumb");
                    String track_no = String.valueOf(i + 1);
                    String poza = c.getJSONObject("PozaPrincipalaMedia").getString("thumb");
                    String idpoza = c.getJSONObject("PozaPrincipalaMedia").getString("id");
                    String nume = c.getString(TAG_TITLU);
                    String cale = c.getString(TAG_CALE);



                    HashMap<String, String> map = new HashMap<String, String>();
                    map.put("track_no", track_no + ".");

                    map.put(TAG_POZA, poza);
                    map.put(TAG_NUME, nume);
                    map.put(TAG_CALE, cale);

                    tracksList.add(map);
                }



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

            return null;
        }


        protected void onPostExecute(String file_url) {
            pDialog.dismiss();
            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    ListAdapter adapter = new SimpleAdapter(
                            getActivity(), tracksList,
                            R.layout.list_faze, new String[] {TAG_POZA, "track_no", TAG_NUME }, new int[] {
                            R.id.list_image,
                            R.id.track_no, R.id.nume_piesa });

                    setListAdapter(adapter);
                    //TextView text = (TextView) getActivity().findViewById(R.id.version);
                    //text.setText(titlu);
                }
            });

        }

    }


}

Answer 1

I'm going to post my comment as an answer, I believe it's the easiest way to quickly solve your problem. If you can control how much JSON is being sent on the server side, then make requests from your java app for page 1, page 2 etc.

Page 1,page 2,etc... could just send out small portions of the JSON you need, then attach a listener (button/scrollview) to request the next page, so on an so forth. Hope this helps!