android – 使用CursorLoader和FilterQueryProvider进行ListView过滤？
作者：互联网
在我们的项目中,我们对Lists进行了大量处理,并在过去使用了以下“模式”：
ListView在Fragment中,在onActivityCreated中初始化,我们首先启动CursorLoaders,然后在onFinish swapCusor中启动ListAdapter.然后,我们使用filterQueryProvider实现了一个搜索功能,它只返回一个带有contentResolver.query(…)的游标.如果我在选择列表中的某些内容时进行了一些方向更改,则在许多情况下会出现以下错误(不定期)：
android.database.StaleDataException: Attempted to access a cursor after it has been closed.
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3378)
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread.access$700(ActivityThread.java:127)
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1162)
12-05 10:36:59.531: E/ACRA(12079): at android.os.Handler.dispatchMessage(Handler.java:99)
12-05 10:36:59.531: E/ACRA(12079): at android.os.Looper.loop(Looper.java:137)
12-05 10:36:59.531: E/ACRA(12079): at android.app.ActivityThread.main(ActivityThread.java:4448)
12-05 10:36:59.531: E/ACRA(12079): at java.lang.reflect.Method.invokeNative(Native Method)
12-05 10:36:59.531: E/ACRA(12079): at java.lang.reflect.Method.invoke(Method.java:511)
12-05 10:36:59.531: E/ACRA(12079): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
12-05 10:36:59.531: E/ACRA(12079): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
12-05 10:36:59.531: E/ACRA(12079): at dalvik.system.NativeStart.main(Native Method)
12-05 10:36:59.531: E/ACRA(12079): Caused by: android.database.StaleDataException: Attempted to access a cursor after it has been closed.
12-05 10:36:59.531: E/ACRA(12079): at android.database.BulkCursorToCursorAdaptor.throwIfCursorIsClosed(BulkCursorToCursorAdaptor.java:75)
12-05 10:36:59.531: E/ACRA(12079): at android.database.BulkCursorToCursorAdaptor.getColumnNames(BulkCursorToCursorAdaptor.java:170)
12-05 10:36:59.531: E/ACRA(12079): at android.database.AbstractCursor.getColumnIndex(AbstractCursor.java:248)
12-05 10:36:59.531: E/ACRA(12079): at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:266)
12-05 10:36:59.531: E/ACRA(12079): at android.database.CursorWrapper.getColumnIndexOrThrow(CursorWrapper.java:78)
12-05 10:36:59.531: E/ACRA(12079): at android.support.v4.widget.CursorAdapter.swapCursor(CursorAdapter.java:344)
12-05 10:36:59.531: E/ACRA(12079): at
这是在方向更改后在onLoadFinished中使用swapCursor时的情况.
我现在使用带参数的restartLoader重新实现过滤器功能,并使用带有附加路径的Contacts.CONTENT_FILTER_URI作为约束,然后将此光标交换到onLoadFinished,所以我删除了filterQueryProvider,它看起来工作正常.
问题是：是否有可能(或良好实践)最初使用CursorLoader和filterQueryProvider？还是我必须决定？因为我在使用filterQueryProvider时会达到相同的结果,只需使用约束null进行过滤,只需加载我所需的联系人列表,然后进行过滤.
有什么建议？我没有通过谷歌找到这方面的mathinc信息;)
这是我当前的LoaderCallbacks实现btw：
private LoaderManager.LoaderCallbacks<Cursor> phoneBookContactsLoaderCallback = new LoaderManager.LoaderCallbacks<Cursor>() {
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// if(constraint != null && constraint.length() > 0) {
// selection = Contacts.DISPLAY_NAME + " LIKE ?";
// selectionArgs = new String [] {"%" + constraint + "%"};
// }
numLoaderManagersRunning++;
String constraint = null;
if(args != null){
constraint = args.getString(CONSTRAINT);
}
Uri uri = null;
if(constraint!= null && !constraint.isEmpty()){
uri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI, constraint);
} else {
uri = Contacts.CONTENT_URI;
}
return new CursorLoader(getActivity(), uri , PROJECTION_PHONEBOOK_CONTACTS,
null, null, Contacts.DISPLAY_NAME + " COLLATE NOCASE ASC");
}
@Override
public void onl oadFinished(Loader<Cursor> loader, Cursor data) {
Logger.e(TAG, "Load finished ");
// phoneBookContactsCursorAdapter.swapCursor(new MatrixCursor(new String [] { Contacts._ID,
// Contacts.DISPLAY_NAME, Contacts.PHOTO_ID }));
phoneBookContactsCursorAdapter.swapCursor(data);
if (actualMultiFilterListener != null){
actualMultiFilterListener.onFilterComplete(data.getCount());
}
//filterList("");
numLoaderManagersRunning--;
if (numLoaderManagersRunning <= 0) {
// The list should now be shown.
if (isResumed()) {
setListShown(true);
} else {
setListShownNoAnimation(true);
}
}
}
@Override
public void onl oaderReset(Loader<Cursor> loader) {
// phoneBookContactsCursorAdapter.swapCursor(null);
Logger.e(TAG, "Load resetted ");
}
};
解决方法:
有点迟,但我遇到了完全相同的问题,评论并没有很好地解释.对于那些面临问题的人来说,解决方案是：
“停止使用FilterQueryProvider.CursorLoader也可以替代它：用你的过滤器重启它,你会没事的.” (source)
意思是;
而不是这样做：
@Override
public Cursor runQuery(CharSequence listId) {
return mDb.getContacts(listId);
}// DO NOT set direct database query, has no observation at all.
要么
@Override
public Cursor runQuery(CharSequence listId) {
return getContentManager.query(....,new String[]{listId}...
}// DO NOT return content manager result, forgets observers.
要么
@Override
public Cursor runQuery(CharSequence listId) {
Bundle bundle = new Bundle();
bundle.putCharSequence("selected", listId);
getLoaderManager().restartLoader(CURSOR_LOADER_CONTACTS, bundle, MainActivity.this);
return null;
}// DO NOT restart the cursor loader with new info, screws observers.
结合使用mContactAdapter.getFilter().filter(id“”); (在应用过滤器时)
做这个：
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
switch (id) {
case CURSOR_LOADER_CONTACTS:
long mListId = 0;
if (args != null) {
mListId = args.getLong(CONTACT_FILTER);
}
return new CursorLoader(this, ContentProvider.CONTACT_DISPLAY_URI, null, ContactTable.COLUMN_GROUP_ID+"=?", new String[]{id+""}, null);
} //Apply filter here with new info comes from 'restartLoader'
return null;
}
结合使用getLoaderManager().restartLoader(MainActivity.CURSOR_LOADER_CONTACTS,bundle,MainActivity.this);
假设MainActivity.this实现LoaderManager.LoaderCallbacks< Cursor>
标签：android,filter,listview,android-cursorloader,list 来源： https://codeday.me/bug/20190612/1226998.html