我尝试使用AsyncTaskLoader Fragment中ViewPager的孩子DayFragment。在我的public class DayFragment extends Fragment
implements LoaderManager.LoaderCallbacks<DayAdapter.DayItem[]> {
private static final int CONTENT_LOADER = 0;
private DayAdapter mAdapter = null;
private int mWeekNumber = 1;
private int mDayCode = 1;
private Table.Timetable mTimetable;
private RecyclerView mRVContent;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final MainActivity mainActivity = (MainActivity) getActivity();
View v = inflater.inflate(R.layout.content, container, false);
mRVContent = (RecyclerView) v.findViewById(R.id.rvContent);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(mainActivity);
mRVContent.setLayoutManager(layoutManager);
mAdapter = new DayAdapter(getActivity());
mRVContent.setAdapter(mAdapter);
//Initialize the cursor loader
getLoaderManager().initLoader(CONTENT_LOADER, null, this).forceLoad();
return v;
}
@Override
public Loader<DayAdapter.DayItem[]> onCreateLoader(final int id, Bundle args) {
if(CONTENT_LOADER == id) {
return new ContentLoader(getContext(), mWeekNumber, mDayCode, mTimetable);
}
return null;
}
@Override
public void onLoadFinished(Loader loader, DayAdapter.DayItem[] items) {
if(CONTENT_LOADER == loader.getId()) {
mAdapter.setIs24HourFormat(SettingsManager.is24HourFormat(getContext()));
mAdapter.clear();
for (DayAdapter.DayItem item : items) {
mAdapter.add(item);
}
mAdapter.notifyDataSetChanged();
if (items.length == 0) {
mRVContent.setBackgroundResource(R.drawable.bg_lesson_empty);
} else {
mRVContent.setBackgroundColor(0xFFFFFFFF);
}
}
}
@Override
public void onLoaderReset(Loader loader) {
}
private static final class ContentLoader extends AsyncTaskLoader<DayAdapter.DayItem[]> {
private final int mWeekNumber;
private final int mDayCode;
private final Table.Timetable mTimetable;
public ContentLoader(Context context, final int weekNumber, final int dayCode,
Table.Timetable timetable) {
super(context);
mWeekNumber = weekNumber;
mDayCode = dayCode;
mTimetable = timetable;
}
@Override
public DayAdapter.DayItem[] loadInBackground() {
DatabaseHandler db = new DatabaseHandler(getContext());
db.openReadable();
List<Table.Lesson> lessons = db.findLessons(mDayCode, mWeekNumber, mTimetable.getId());
DayAdapter.DayItem[] items = new DayAdapter.DayItem[lessons.size()];
for (int i = 0; i < items.length; ++i) {
Table.Lesson lesson = lessons.get(i);
Table.Subject subject = db.getSubject(lesson.getSubjectId());
Table.Teacher teacher = db.getTeacher(lesson.getTeacherId());
if (teacher == null) {
teacher = new Table.Teacher(""); //Empty name
}
items[i] = new DayAdapter.DayItem()
.setId(lesson.getId())
.setTitle(subject.getTitle())
.setSubtitle(teacher.getName()));
}
db.close();
return items;
}
}
}
的代码下面：
PageAdapater public class PageAdapter extends FragmentStatePagerAdapter {
public static final int PAGE_COUNT = 7;
private int mWeekNumber;
private final int[] mDayCodes;
private final String[] mDays;
private final DayFragment[] mFragments = new DayFragment[7];
private Table.Timetable mTimetable;
private boolean mIsRebuildMode = false;
public PageAdapter(Context context, FragmentManager fm,
Table.Timetable timetable, final int weekNumber) {
super(fm);
//Initialize class members
}
@Override
public Fragment getItem(int position) {
DayFragment dayFragment;
if (mFragments[position] == null) {
dayFragment = new DayFragment();
Bundle args = new Bundle();
args.putSerializable(Keys.TIMETABLE, mTimetable);
dayFragment.setArguments(args);
dayFragment.setWeekNumber(mWeekNumber);
dayFragment.setDayCode(mDayCodes[position]);
mFragments[position]= dayFragment;
} else {
dayFragment = mFragments[position];
}
return dayFragment;
}
@Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {
//do nothing here! no call to super.restoreState(arg0, arg1);
}
public void setWeekNumber(final int weekNumber) {
mWeekNumber = weekNumber;
Arrays.fill(mFragments, null);
}
public void setIsRebuildMode(final boolean isRebuildMode) {
mIsRebuildMode = isRebuildMode;
}
@Override
public CharSequence getPageTitle(final int position) {
return mDays[position];
}
@Override
public int getCount() {
return PAGE_COUNT;
}
@Override
public int getItemPosition(Object object) {
if(mIsRebuildMode) {
return POSITION_NONE;
}
return super.getItemPosition(object);
}
}
onLoadFinished但它并没有调用Log方法。我检查了LoaderManager输出... onCreateLoader来电onLoadFinished，但除了第一次运行（当应用启动时，ViewPager显示第一页（Fragment时，它永远不会调用LoaderManager {1}}））。一切都好！如果我将页面切换到下一页和下一页并返回第一页onLoadFinished，也不会为第一页调用onCreateLoader。但它会创建加载器调用onLoaderReset并重置加载器调用[["aniket", 6], ["shivam", 7], ["tiwari", 8], ["abhijeet", 9]]
。这是Google的笑话吗？
答案 0 :(得分：1)
请参阅片段生命周期。 ViewPager不会创建片段，只需轻扫它们
- 启动ViewPager ： 创建 ：createView ：开始 ：简历
如果你滑动片段，没有改变
---睡觉智能手机 ：暂停 ：停止
---唤醒智能手机 ：开始 ： 恢复 ：暂停
---关闭ViewPager ： 停 ：分离