我已经在片段中使用了json和我的Listview但是它需要时间，因为我有190个对象，所以我希望它只显示15个Json项目，如果用户滚动到结尾将会更多15个项目。我从dropbox获得的json文件大小为2,3MB。谁能告诉我一个好建议？提前谢谢。
以下是代码。
public class UniversityFragment extends Fragment implements OnScrollListener{
ListView lv;
private ProgressDialog pDialog;
// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_NAME = "name";
private static final String TAG_ADDRESS = "address";
private static final String TAG_CityProvince = "city/province";
private static final String TAG_Country = "country";
private static final String TAG_PHONE_OFFICE = "officephone";
private static final String TAG_Fax = "fax";
private static final String TAG_EMAIL = "email";
private static final String TAG_Site = "site";
private static final String TAG_image = "image";
int textlength = 0;
// contacts JSONArray
JSONArray contacts = null;
JSONObject jsonobject;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
// Search EditText
EditText inputSearch;
public UniversityFragment() {
}
@SuppressLint("CutPasteId")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_university,
container, false);
// Execute DownloadJSON AsyncTask
contactList = new ArrayList<HashMap<String, String>>();
lv = (ListView) rootView.findViewById(R.id.listView1);
inputSearch = (EditText) rootView.findViewById(R.id.inputSearch);
lv.setTextFilterEnabled(true);
inputSearch.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence cs, int start, int before,
int count) {
// TODO Auto-generated method stub
// When user changed the Text
// UniversityFragment.this.adapter.getFilter().filter(cs);
}
@Override
public void beforeTextChanged(CharSequence cs, int start,
int count, int after) {
// TODO Auto-generated method stub
try {
// ((Filterable)
// UniversityFragment.this.contacts).getFilter().filter(cs);
} catch (Exception e) {
// TODO: handle exception
Toast.makeText(getActivity(), "" + e, Toast.LENGTH_SHORT)
.show();
}
// lv.setTextFilterEnabled(true);
}
@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
}
});
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// TODO Auto-generated method stub
Toast.makeText(getActivity(), "Clicked" + position,
Toast.LENGTH_LONG).show();
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cp = ((TextView) view.findViewById(R.id.CPt)).getText()
.toString();
String country = ((TextView) view.findViewById(R.id.countryt))
.getText().toString();
String fax = ((TextView) view.findViewById(R.id.faxt))
.getText().toString();
String site = ((TextView) view.findViewById(R.id.sitet))
.getText().toString();
String email = ((TextView) view.findViewById(R.id.emailt))
.getText().toString();
String phone = ((TextView) view.findViewById(R.id.phonet))
.getText().toString();
String address = ((TextView) view.findViewById(R.id.addresst))
.getText().toString();
// Starting single contact activity
Intent in = new Intent(getActivity(), SingleListItem.class);
in.putExtra("email", email);
in.putExtra("city/province", cp);
in.putExtra("country", country);
in.putExtra("fax", fax);
in.putExtra("site", site);
in.putExtra("name", name);
in.putExtra("officephone", phone);
in.putExtra("address", address);enter code here
startActivity(in);
}
});
lv.setOnScrollListener(new OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
if (firstVisibleItem+visibleItemCount == totalItemCount && totalItemCount!=0) {
}
}
});
// Calling async task to get json
new GetContacts().execute();
return rootView;
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(getActivity());
pDialog.setTitle("Loading");
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
// Create an array
contactList = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
String url = "https://dl.dropbox.com........";
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
enter code here
// Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CONTACTS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String name = c.getString(TAG_NAME);
String address = c.getString(TAG_ADDRESS);
String country = c.getString(TAG_Country);
String cityprovince = c.getString(TAG_CityProvince);
String officephone = c.getString(TAG_PHONE_OFFICE);
String fax = c.getString(TAG_Fax);
String email = c.getString(TAG_EMAIL);
String site = c.getString(TAG_Site);
// // Phone node is JSON Object
// JSONObject phone = c.getJSONObject(TAG_PHONE);
// String home = phone.getString(TAG_PHONE_HOME);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_NAME, name);
contact.put(TAG_ADDRESS, address);
contact.put(TAG_CityProvince, cityprovince);
contact.put(TAG_Country, country);
contact.put(TAG_PHONE_OFFICE, officephone);
contact.put(TAG_EMAIL, email);
contact.put(TAG_Site, site);
contact.put(TAG_Fax, fax);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
Toast.makeText(getActivity(), "Thank for your patience", Toast.LENGTH_LONG).show();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(getActivity(), contactList,
R.layout.listsingleitem, new String[] { TAG_NAME,
TAG_ADDRESS, TAG_CityProvince, TAG_Country,
TAG_PHONE_OFFICE, TAG_Fax, TAG_EMAIL, TAG_Site },
new int[] { R.id.name, R.id.addresst, R.id.CPt,
R.id.countryt, R.id.phonet, R.id.faxt, R.id.emailt,
R.id.sitet });
adapter.notify();
//adapter.notifyDataSetChanged();
lv.setAdapter(adapter);
}
}
答案 0 :(得分：0)
您需要实现无限适配器（自定义列表视图适配器）以支持并发加载和显示。
请参阅本教程：http://www.survivingwithandroid.com/2013/10/android-listview-endless-adapter.html