问题
public class NewMovie extends Activity {
GridView lv;
Vibrator vibrator;
SimpleAdapter adapter;
Button b;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
Log.i("Category", MainActivity.movie_Category);
setContentView(R.layout.new_movie);
vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
lv = (GridView) findViewById(R.id.grid_view);
// URL to the JSON data
String strUrl = "http://vaibhavtech.com/work/android/movie_list.php?category="
+ MainActivity.movie_Category + "&sub_category=new";
// Creating a new non-ui thread task to download json data
DownloadTask downloadTask = new DownloadTask();
// Starting the download processt
downloadTask.execute(strUrl);
// Getting a reference to ListView of activity_main
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// // TODO Auto-generated method stub
vibrator.vibrate(40);
LayoutInflater inflater = getLayoutInflater();
View view = inflater.inflate(R.layout.customtoast,
(ViewGroup) findViewById(R.id.custom_toast_layout));
Toast toast = new Toast(getApplicationContext());
toast.setDuration(Toast.LENGTH_LONG);
toast.setGravity(Gravity.CENTER_HORIZONTAL, 0, 0);
toast.setView(view);
toast.show();
MainActivity.movie_Id = ((TextView) arg1
.findViewById(R.id.tv_girdview_content_id)).getText()
.toString();
Log.i("Name is", MainActivity.movie_Id);
startActivity(new Intent(NewMovie.this, MovieDescription.class));
}
});
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
try {
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
HttpURLConnection urlConnection = (HttpURLConnection) url
.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(
iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (Exception e) {
Log.d("Exception while downloading url", e.toString());
} finally {
iStream.close();
}
return data;
}
/** AsyncTask to download json data */
private class DownloadTask extends AsyncTask<String, Integer, String> {
String data = null;
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
@Override
protected void onPostExecute(String result) {
// The parsing of the xml data is done in a non-ui thread
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
// Start parsing xml data
listViewLoaderTask.execute(result);
}
}
/** AsyncTask to parse json data and load ListView */
private class ListViewLoaderTask extends
AsyncTask<String, Void, SimpleAdapter> {
JSONObject jObject;
// Doing the parsing of xml data in a non-ui thread
@Override
protected SimpleAdapter doInBackground(String... strJson) {
try {
jObject = new JSONObject(strJson[0]);
MovieParser countryJsonParser = new MovieParser();
countryJsonParser.parse(jObject);
} catch (Exception e) {
Log.d("JSON Exception1", e.toString());
}
// Instantiating json parser class
MovieParser countryJsonParser = new MovieParser();
// A list object to store the parsed countries list
List<HashMap<String, Object>> countries = null;
try {
// Getting the parsed data as a List construct
countries = countryJsonParser.parse(jObject);
} catch (Exception e) {
Log.d("Exception", e.toString());
}
// Keys used in Hashmap
String[] from = { "image", "id", "year", "duration", "name" };
// Ids of views in listview_layout
// int[] to = {
// R.id.iv_radio_data_image,R.id.tv_radio_data_id,R.id.tv_radio_data_like,R.id.tv_radio_data_rating,R.id.tv_radio_data_listner,R.id.tv_radio_data_radio_url,R.id.tv_radio_data_name};
int[] to = { R.id.iv_girdview_content_image,
R.id.tv_girdview_content_id, R.id.tv_girdview_content_like,
R.id.tv_girdview_content_listner,
R.id.tv_girdview_content_name };
// Instantiating an adapter to store each items
// R.layout.listview_layout defines the layout of each item
adapter = new SimpleAdapter(getBaseContext(), countries,
R.layout.grid_view_content, from, to);
return adapter;
// lv.setAdapter(new ListAdapter(getApplicationContext()));
}
/** Invoked by the Android on "doInBackground" is executed */
@Override
protected void onPostExecute(SimpleAdapter adapter) {
// Setting adapter for the listview
lv.setAdapter(adapter);
for (int i = 0; i < adapter.getCount(); i++) {
HashMap<String, Object> hm = (HashMap<String, Object>) adapter
.getItem(i);
String imgUrl = (String) hm.get("flag_path");
ImageLoaderTask imageLoaderTask = new ImageLoaderTask();
HashMap<String, Object> hmDownload = new HashMap<String, Object>();
hm.put("flag_path", imgUrl);
hm.put("position", i);
// Starting ImageLoaderTask to download and populate image in
// the listview
imageLoaderTask.execute(hm);
}
// }
}
/** AsyncTask to download and load an image in ListView */
private class ImageLoaderTask
extends
AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>> {
@Override
protected HashMap<String, Object> doInBackground(
HashMap<String, Object>... hm) {
InputStream iStream = null;
String imgUrl = (String) hm[0].get("flag_path");
int position = (Integer) hm[0].get("position");
URL url;
try {
url = new URL(imgUrl);
// Creating an http connection to communicate with url
HttpURLConnection urlConnection = (HttpURLConnection) url
.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
// Getting Caching directory
File cacheDirectory = getBaseContext().getCacheDir();
// Temporary file to store the downloaded image
File tmpFile = new File(cacheDirectory.getPath() + "/wpta_"
+ position + ".png");
// The FileOutputStream to the temporary file
FileOutputStream fOutStream = new FileOutputStream(tmpFile);
// Creating a bitmap from the downloaded inputstream
Bitmap b = BitmapFactory.decodeStream(iStream);
// Writing the bitmap to the temporary file as png file
b.compress(Bitmap.CompressFormat.PNG, 100, fOutStream);
// Flush the FileOutputStream
fOutStream.flush();
// Close the FileOutputStream
fOutStream.close();
// Create a hashmap object to store image path and its
// position in the listview
HashMap<String, Object> hmBitmap = new HashMap<String, Object>();
// Storing the path to the temporary image file
hmBitmap.put("image", tmpFile.getPath());
// Storing the position of the image in the listview
hmBitmap.put("position", position);
// Returning the HashMap object containing the image path
// and position
return hmBitmap;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(HashMap<String, Object> result) {
// Getting the path to the downloaded image
String path = (String) result.get("image");
// Getting the position of the downloaded image
int position = (Integer) result.get("position");
// Getting adapter of the listview
adapter = (SimpleAdapter) lv.getAdapter();
// Getting the hashmap object at the specified position of the
// listview
HashMap<String, Object> hm = (HashMap<String, Object>) adapter
.getItem(position);
// Overwriting the existing path in the adapter
hm.put("image", path);
// lv.invalidateViews();
adapter.notifyDataSetChanged();
}
}
}
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PLZ help i found this ans from loag time i want loading more image from server when scrolling like facebook app style. above my code plz help me.
回答1:
Benji helped me here.
public class EndlessScrollListener implements OnScrollListener {
private int visibleThreshold = 5;
private int currentPage = 0;
private int previousTotal = 0;
private boolean loading = true;
public EndlessScrollListener() {
}
public EndlessScrollListener(int visibleThreshold) {
this.visibleThreshold = visibleThreshold;
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
currentPage++;
}
}
if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
// I load the next page of gigs using a background task,
// but you can call any function here.
new LoadGigsTask().execute(currentPage + 1);
loading = true;
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
}
Check this out
来源：https://stackoverflow.com/questions/19632041/i-want-grid-view-with-loading-by-scroll-i-have-image-fetch-from-sever-but-i-want