[英]auto load more items with android
我有這段代碼可以從網站上獲取JSON數據,並且運行良好
我想做的是,加載10個項目,當用戶滾動到底部時,它加載另外10個項目...等,直到項目完成
public class MainActivity extends Activity {
private static final String TAG = MainActivity.class.getSimpleName();
private ListView listView;
private FeedListAdapter listAdapter;
private List<FeedItem> feedItems;
//Feeds URL - Your Website URL where you uploaded the admin panel
private String URL_FEED = "http://EXAMPLE.COM";
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Getting feeds from the website into listview
listView = (ListView) findViewById(R.id.list);
feedItems = new ArrayList<FeedItem>();
listAdapter = new FeedListAdapter(this, feedItems);
listView.setAdapter(listAdapter);
// making fresh volley request and getting json
JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
URL_FEED, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
VolleyLog.d(TAG, "Response: " + response.toString());
if (response != null) {
parseJsonFeed(response);
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
});
// Adding request to volley request queue
AppController.getInstance().addToRequestQueue(jsonReq);
}
/**
* Parsing json reponse and passing the data to feed view list adapter
* */
private void parseJsonFeed(JSONObject response) {
try {
JSONArray feedArray = response.getJSONArray("feed");
for (int i = 0; i < feedArray.length(); i++) {
JSONObject feedObj = (JSONObject) feedArray.get(i);
FeedItem item = new FeedItem();
item.setId(feedObj.getInt("id"));
item.setName(feedObj.getString("name"));
// Image might be null sometimes
String image = feedObj.isNull("image") ? null : feedObj
.getString("image");
item.setImge(image);
item.setStatus(feedObj.getString("status"));
item.setProfilePic(feedObj.getString("profilePic"));
item.setTimeStamp(feedObj.getString("timeStamp"));
// url might be null sometimes
String feedUrl = feedObj.isNull("url") ? null : feedObj
.getString("url");
item.setUrl(feedUrl);
feedItems.add(item);
}
// notify data changes to list adapater
listAdapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
///Menus functions
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int itemId = item.getItemId();
switch (itemId) {
case R.id.action_logout:
session.logoutUser();
break;
case R.id.myProfile:
Intent intent2 = new Intent(this, ProfileActivity.class);
startActivity(intent2);
break;
case R.id.addPhoto:
Intent intent1 = new Intent(this, UploadPhoto.class);
startActivity(intent1);
break;
}
// TODO Auto-generated method stub
return super.onOptionsItemSelected(item);
}
}
實現onscrolllistener()
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
this.currentFirstVisibleItem = firstVisibleItem;
this.currentVisibleItemCount = visibleItemCount;
}
public void onScrollStateChanged(AbsListView view, int scrollState) {
this.currentScrollState = scrollState;
this.isScrollCompleted();
}
private void isScrollCompleted() {
if (this.currentVisibleItemCount > 0 && this.currentScrollState == SCROLL_STATE_IDLE) {
/*** In this way I detect if there's been a scroll which has completed ***/
/*** do the work for load more date! ***/
if(!isLoading){
isLoading = true;
GetMoreJsonData();
}
}
}
當您實現並將此偵聽器添加到listview時,這將檢測到listview的末尾,因為滾動位置位於list的末尾只是獲得了更多數據。 在加載數據期間,滾動位置結束時,您需要一個標志來立即加載數據。 因此,如果正在加載數據,並且在此期間您向上滾動然后向下滾動,則將不會獲得更多要復制的數據。
您可以創建一個新方法,並移動發出新的齊射請求並在其中獲取json的代碼:
private void GetMoreJsonData()
{
// making fresh volley request and getting json
JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
URL_FEED, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
VolleyLog.d(TAG, "Response: " + response.toString());
if (response != null) {
parseJsonFeed(response);
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
});
// Adding request to volley request queue
AppController.getInstance().addToRequestQueue(jsonReq);
}
發送json請求時不要忘記獲得10-10個項目
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