我正在做一个报价应用程序，从数据库中提取报价，我需要在 ViewPager 中显示报价。
我已经创建了我的 Cursor PagerAdapter ，它似乎运行良好。
public class MyCursorPagerAdapter extends PagerAdapter {
private Cursor cursor;
private LayoutInflater inflater;
public MyCursorPagerAdapter(Context context, Cursor cursor) {
Log.d(MainActivity.TAG, "MyCursorPagerAdapter.onCreate()");
this.cursor = cursor;
this.inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public void swapCursor(Cursor cursor) {
//if(cursor != null) {
Log.d(MainActivity.TAG, "swapCursor().");
this.cursor = cursor;
//notifyDataSetChanged();
//}
}
/**
* Metóda destroyItem
*/
@Override
public void destroyItem(View view, int position, Object object) {
//cursor.moveToPosition(position);
((ViewPager) view).removeView((LinearLayout) object);
}
/**
* Vráti počet prvkov
*/
@Override
public int getCount() {
if(cursor == null) {
return 0;
} else {
//return cursor.getCount();
return 1000;
}
}
@Override
public Object instantiateItem(View view, int position) {
position = position % cursor.getCount();
cursor.moveToPosition(position);
LinearLayout layout = (LinearLayout) inflater.inflate(R.layout.pager_item, null);
TextView messageTextView = (TextView) layout.findViewById(R.id.message_textview);
TextView authorTextView = (TextView) layout.findViewById(R.id.author_textview);
messageTextView.setText(cursor.getString(cursor.getColumnIndex(QuoteDatabaseHelper.COLUMN_MESSAGE)));
authorTextView.setText(cursor.getString(cursor.getColumnIndex(QuoteDatabaseHelper.COLUMN_AUTHOR)));
((ViewPager) view).addView(layout);
return layout;
}
/**
* Metóda isViewFromObject
*/
@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
}
我还使用 CursorLoader 异步加载数据库
public class MainActivity extends FragmentActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
myCursorPagerAdapter = new MyCursorPagerAdapter(this, null);
pager = (ViewPager) findViewById(R.id.viewPager);
pager.setAdapter(myCursorPagerAdapter);
getSupportLoaderManager().initLoader(-1, null, this);
}
@Override
public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) {
return new CursorLoader(this, QuoteContentProvider.CONTENT_URI, null, null, null, null);
}
@Override
public void onLoadFinished(Loader<Cursor> arg0, Cursor cursor) {
Log.d(MainActivity.TAG, "onLoadFinished()");
myCursorPagerAdapter.swapCursor(cursor);
this.cursor = cursor;
pager.setCurrentItem((int) (myCursorPagerAdapter.getCount() / 2), false);
pager.startAnimation(animation);
}
@Override
public void onLoaderReset(Loader<Cursor> arg0) {
myCursorPagerAdapter.swapCursor(null);
}
}
与内容提供商
public class QuoteContentProvider extends ContentProvider {
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
Cursor cursor = db.query(TABLE_NAME, projection, selection, selectionArgs, null, null, "RANDOM()");
cursor.setNotificationUri(getContext().getContentResolver(), uri);
Log.d(MainActivity.TAG, "QuoteContentProvider.query() - cursor.getCount(): " + cursor.getCount());
// getContext().getContentResolver().notifyChange(uri, null);
return cursor;
}
}
一切正常，它很好地加载了所有引号，但现在我需要执行搜索。所以我做了一个查询数据库的方法
public void search(String keyword) {
Log.d(MainActivity.TAG, "Search keyword: " + keyword);
getContentResolver().query(QuoteContentProvider.CONTENT_URI, null, QuoteContentProvider.COLUMN_AUTHOR + " LIKE '%" + keyword + "%' OR " + QuoteContentProvider.COLUMN_MESSAGE + " LIKE '%" + keyword + "%'", null, null);
}
查询很好，我可以看到 ContentProvider.query() 被调用并打印出cursor.getCount()，
然而，现在即使设置了cursor.setNotificationUri()，MainActivity 中的onLoadFinished 也不会被调用，并且我认为它可以工作，因为它在应用程序启动时第一次工作。
我实际上尝试使用内容提供程序插入一些数据并调用 getContext().getContentResolver().notifyChange(uri, null);它触发了 OnLoadFinished 所以我不知道为什么这个不同的查询没有触发 OnLoadFinished。
非常感谢您能理解这一点。
