我需要做一个ListAdapter的起价多ContentProviders p $ psents数据。该ContentProviders自己重新present每一个表从关系型数据库。
I need to make a ListAdapter that presents data from multiple ContentProviders. The ContentProviders themselves represent one table each from relational database.
我想使用CursorLoader系统检索汇总数据到ListView控件。 这是可以做到1装载机或做我需要使用多个装载机?我倒是preFER使用一个。
I want to use the CursorLoader system to retrieve aggregate data into ListView. Is this possible to do with 1 loader or do I need to use multiple loaders? I'd prefer to use one.
我不知道我怎么能有2 ContentProviders互相交流之外做手工code这似乎不是一个很好的选择无论是加入。的
您必须编写自定义Loader类。例如:
You will have to write a Custom Loader class. For example:
public class FooLoader extends AsyncTaskLoader {
Context context;
public FooLoader(Context context) {
super(context);
this.context = context;
}
@Override
public Cursor loadInBackground() {
Log.d(TAG, "loadInBackground");
YourDatabase dbHelper = new YourDataBase(context);
SQLiteDatabase db= dbHelper.getReadableDatabase();
/*** create a custom cursor whether it is join of multiple tables or complex query**/
Cursor cursor = db.query(<TableName>, null,null, null, null, null, null, null);
return cursor;
}
}
在调用活动或片段的onCreate()
方法,你需要调用自定义的类装载器:
In the calling activity or fragments onCreate()
method, you would need to call the custom loader class:
public class MyFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate():" + mContent);
Loader loader = getLoaderManager().initLoader(0, null, this);
loader.forceLoad();
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
Log.d(TAG, "onCreateLoader()") ;
return new FooLoader(getActivity());
}
@Override
public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
Log.d(TAG, "onLoadFinished");
}
@Override
public void onLoaderReset(Loader<Cursor> cursorLoader) {
}
}