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/*
* This is an adapted version of Android's original CursorLoader
* without all the ContentProvider-specific bits.
*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.mozilla.gecko.home;
import android.content.Context;
import android.database.Cursor;
import android.support.v4.content.AsyncTaskLoader;
import org.mozilla.gecko.GeckoApplication;
/**
* A copy of the framework's {@link android.content.CursorLoader} that
* instead allows the caller to load the Cursor themselves via the abstract
* {@link #loadCursor()} method, rather than calling out to a ContentProvider via
* class methods.
*
* For new code, prefer {@link android.content.CursorLoader} (see @deprecated).
*
* This was originally created to re-use existing code which loaded Cursors manually.
*
* @deprecated since the framework provides an implementation, we'd like to eventually remove
* this class to reduce maintenance burden. Originally planned for bug 1239491, but
* it'd be more efficient to do this over time, rather than all at once.
*/
@Deprecated
public abstract class SimpleCursorLoader extends AsyncTaskLoader<Cursor> {
final ForceLoadContentObserver mObserver;
Cursor mCursor;
public SimpleCursorLoader(Context context) {
super(context);
mObserver = new ForceLoadContentObserver();
}
/**
* Loads the target cursor for this loader. This method is called
* on a worker thread.
*/
protected abstract Cursor loadCursor();
/* Runs on a worker thread */
@Override
public Cursor loadInBackground() {
Cursor cursor = loadCursor();
if (cursor != null) {
// Ensure the cursor window is filled
cursor.getCount();
cursor.registerContentObserver(mObserver);
}
return cursor;
}
/* Runs on the UI thread */
@Override
public void deliverResult(Cursor cursor) {
if (isReset()) {
// An async query came in while the loader is stopped
if (cursor != null) {
cursor.close();
}
return;
}
Cursor oldCursor = mCursor;
mCursor = cursor;
if (isStarted()) {
super.deliverResult(cursor);
}
if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
oldCursor.close();
// Trying to read from the closed cursor will cause crashes, hence we should make
// sure that no adapters/LoaderCallbacks are holding onto this cursor.
GeckoApplication.getRefWatcher(getContext()).watch(oldCursor);
}
}
/**
* Starts an asynchronous load of the list data. When the result is ready the callbacks
* will be called on the UI thread. If a previous load has been completed and is still valid
* the result may be passed to the callbacks immediately.
*
* Must be called from the UI thread
*/
@Override
protected void onStartLoading() {
if (mCursor != null) {
deliverResult(mCursor);
}
if (takeContentChanged() || mCursor == null) {
forceLoad();
}
}
/**
* Must be called from the UI thread
*/
@Override
protected void onStopLoading() {
// Attempt to cancel the current load task if possible.
cancelLoad();
}
@Override
public void onCanceled(Cursor cursor) {
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
}
@Override
protected void onReset() {
super.onReset();
// Ensure the loader is stopped
onStopLoading();
if (mCursor != null && !mCursor.isClosed()) {
mCursor.close();
}
mCursor = null;
}
}
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