从 AsyncTask 填充 ListView 的 Android 小部件
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【中文标题】从 AsyncTask 填充 ListView 的 Android 小部件【英文标题】：Android Widget with ListView populated from AsyncTask 【发布时间】：2018-03-25 22:34:28 【问题描述】：我正在为我的应用程序创建一个小部件，但是当我必须填充列表视图时我被卡住了。我使用我在 WidgetDataProvider（实现 RemoteViewsService.RemoteViewsFactory）的 onCreate() 中调用的 asynctask 从我的 web db 中获取每个项目。 问题是，通常当我创建小部件时，它不会填充列表，我必须等待几秒钟才能在主屏幕中释放小部件。
如果我抓住并释放小部件，它会如下所示：empty widget
如果我等待，它会像这样显示：right widget
这是我的代码：
AppWidget
public class AppWidget extends AppWidgetProvider
static void updateAppWidget(Context context, AppWidgetManager appWidgetManager, int appWidgetId)
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.app_widget);
Intent intent = new Intent(context, LoginActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
views.setOnClickPendingIntent(R.id.widget_title, pendingIntent);
views.setRemoteAdapter(R.id.widget_listView, new Intent(context, WidgetService.class));
appWidgetManager.updateAppWidget(appWidgetId, views);
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
super.onUpdate(context, appWidgetManager, appWidgetIds);
for (int appWidgetId : appWidgetIds)
updateAppWidget(context, appWidgetManager, appWidgetId);
@Override
public void onEnabled(Context context)
@Override
public void onDisabled(Context context)
**WidgetService **
public class WidgetService extends RemoteViewsService
@Override
public RemoteViewsFactory onGetViewFactory(Intent intent)
return new WidgetDataRemote(this, intent);
WidgetDataRemote
public class WidgetDataRemoteimplements RemoteViewsService.RemoteViewsFactory
Context context;
Intent intent;
ArrayList<String> date = new ArrayList<>();
ArrayList<String> subj = new ArrayList<>();
ArrayList<String> type = new ArrayList<>();
ArrayList<String> comment = new ArrayList<>();
JSONParser jsonParser = new JSONParser();
ArrayList<String> subjFromDb = new ArrayList<>();
int pippo = 0;
public WidgetDataRemote(Context context, Intent intent)
this.context = context;
this.intent = intent;
@Override
public RemoteViews getViewAt(int position)
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.item_widget);
remoteViews.setTextViewText(R.id.task_data, date.get(position));
remoteViews.setTextViewText(R.id.task_subject, subj.get(position));
remoteViews.setTextViewText(R.id.task_type, type.get(position));
remoteViews.setTextViewText(R.id.task_comment, comment.get(position));
return remoteViews;
@Override
public void onCreate()
new LoadSubjects().execute();
@Override
public void onDataSetChanged()
@Override
public void onDestroy()
date.clear();
subj.clear();
type.clear();
comment.clear();
@Override
public int getCount()
return date.size();
@Override
public RemoteViews getLoadingView()
return null;
@Override
public int getViewTypeCount()
return 1;
@Override
public long getItemId(int id)
return id;
@Override
public boolean hasStableIds()
return true;
class LoadSubjects extends AsyncTask<String, String, String>
@Override
protected void onPreExecute()
super.onPreExecute();
subjFromDb.clear();
pippo = 0;
@Override
protected String doInBackground(String... args)
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("class", User.getClasse()));
JSONArray json = jsonParser.makeHttpRequestArray(Constants.URL_LOAD_SUBJECTS, "POST", params);
try
if (!json.toString().equals("[null]"))
for (int i = 0; i < json.length(); i++)
JSONObject c = json.getJSONObject(i);
String subj = c.getString(Constants.TAG_NAME);
subjFromDb.add(subj);
else
pippo = 1;
catch (JSONException e)
e.printStackTrace();
return null;
protected void onPostExecute(String file_url)
if (pippo == 0)
new LoadTasks().execute();
class LoadTasks extends AsyncTask<String, String, String>
@Override
protected void onPreExecute()
super.onPreExecute();
pippo = 0;
@Override
protected String doInBackground(String... args)
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("id_class", User.getClasse()));
JSONArray json = jsonParser.makeHttpRequestArray(Constants.URL_LOAD_TASKS, "POST", params);
try
if (!json.toString().equals("[null]"))
for (int i = 0; i < json.length(); i++)
JSONObject c = json.getJSONObject(i);
Date data = null;
try
data = new SimpleDateFormat("yyyy-MM-dd").parse(c.getString(Constants.TAG_DATE));
catch (ParseException e)
e.printStackTrace();
String newDate = new SimpleDateFormat("dd/MM/yyyy").format(data);
if (subjFromDb.contains(c.getString(Constants.TAG_SUBJECT)))
date.add(newDate);
subj.add(c.getString(Constants.TAG_SUBJECT));
type.add(c.getString(Constants.TAG_TYPE));
comment.add(c.getString(Constants.TAG_COMMENT));
else
pippo = 1;
catch (JSONException e)
e.printStackTrace();
return null;
protected void onPostExecute(String file_url)
if (pippo == 0)
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
ComponentName thisWidget = new ComponentName(context, WidgetDataProvider.class);
int[] appWidgetIds = appWidgetManager.getAppWidgetIds(thisWidget);
appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.widget_listView);
// I use this to update the listview after fetch data. Is it correct?
【问题讨论】：
【参考方案1】：我仅使用 TimerTask 并在 onPostExecute 中修改更新过程就解决了我的问题。这是我更改的文件：
WidgetDataRemote
public class WidgetDataRemote implements RemoteViewsService.RemoteViewsFactory
final Context context;
Intent intent;
ArrayList<String> date = new ArrayList<>();
ArrayList<String> subj = new ArrayList<>();
ArrayList<String> type = new ArrayList<>();
ArrayList<String> comment = new ArrayList<>();
JSONParser jsonParser = new JSONParser();
ArrayList<String> subjFromDb = new ArrayList<>();
final Context sad;
int pippo = 0;
public WidgetDataRemote(Context context, Intent intent)
this.context = context;
this.intent = intent;
sad = context;
final Handler handler = new Handler();
Timer timer = new Timer();
TimerTask doAsynchronousTask = new TimerTask()
@Override
public void run()
handler.post(new Runnable()
public void run()
try
new LoadSubjects().execute();
catch (Exception ignored)
);
;
timer.schedule(doAsynchronousTask, 0, 60000);
@Override
public RemoteViews getViewAt(int position)
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.item_widget);
if(date.size()>0)
remoteViews.setTextViewText(R.id.task_data, date.get(position));
remoteViews.setTextViewText(R.id.task_subject, subj.get(position));
remoteViews.setTextViewText(R.id.task_type, type.get(position));
remoteViews.setTextViewText(R.id.task_comment, comment.get(position));
else
remoteViews.setTextViewText(R.id.task_data, "");
remoteViews.setTextViewText(R.id.task_subject, "loading");
remoteViews.setTextViewText(R.id.task_type, "");
remoteViews.setTextViewText(R.id.task_comment, "");
return remoteViews;
@Override
public void onCreate()
Toast.makeText(context, "Loading...", Toast.LENGTH_LONG).show();
@Override
public void onDataSetChanged()
@Override
public void onDestroy()
date.clear();
subj.clear();
type.clear();
comment.clear();
@Override
public int getCount()
return date.size();
@Override
public RemoteViews getLoadingView()
return null;
@Override
public int getViewTypeCount()
return 1;
@Override
public long getItemId(int id)
return id;
@Override
public boolean hasStableIds()
return true;
class LoadSubjects extends AsyncTask<String, String, String>
@Override
protected void onPreExecute()
super.onPreExecute();
subjFromDb.clear();
pippo = 0;
@Override
protected String doInBackground(String... args)
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("class", User.getClasse()));
JSONArray json = jsonParser.makeHttpRequestArray(Constants.URL_LOAD_SUBJECTS, "POST", params);
try
if (!json.toString().equals("[null]"))
for (int i = 0; i < json.length(); i++)
JSONObject c = json.getJSONObject(i);
String subj = c.getString(Constants.TAG_NAME);
subjFromDb.add(subj);
else
pippo = 1;
catch (JSONException e)
e.printStackTrace();
return null;
protected void onPostExecute(String file_url)
if (pippo == 0)
new LoadTasks().execute();
class LoadTasks extends AsyncTask<String, String, String>
@Override
protected void onPreExecute()
super.onPreExecute();
date.clear();
subj.clear();
type.clear();
comment.clear();
pippo = 0;
@Override
protected String doInBackground(String... args)
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("id_class", User.getClasse()));
JSONArray json = jsonParser.makeHttpRequestArray(Constants.URL_LOAD_TASKS, "POST", params);
try
if (!json.toString().equals("[null]"))
for (int i = 0; i < json.length(); i++)
JSONObject c = json.getJSONObject(i);
Date data = null;
try
data = new SimpleDateFormat("yyyy-MM-dd").parse(c.getString(Constants.TAG_DATE));
catch (ParseException e)
e.printStackTrace();
String newDate = new SimpleDateFormat("dd/MM/yyyy").format(data);
if (subjFromDb.contains(c.getString(Constants.TAG_SUBJECT)))
date.add(newDate);
subj.add(c.getString(Constants.TAG_SUBJECT));
type.add(c.getString(Constants.TAG_TYPE));
comment.add(c.getString(Constants.TAG_COMMENT));
else
pippo = 1;
catch (JSONException e)
e.printStackTrace();
return null;
protected void onPostExecute(String file_url)
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(sad);
appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetManager.getAppWidgetIds(new ComponentName(sad, AppWidget.class)), R.id.widget_listView);
【讨论】：
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