该应用程序使用 android viewpager2 (androidx.viewpager2:viewpager2:1.0.0-beta04) 来显示幻灯片。每张幻灯片的上半部分都有视频，下半部分有文字。每张幻灯片都是使用相同的片段类构建的（下面给出的代码）
如果一张一张地滑动，幻灯片就可以正常工作，但是如果尝试打开“setCurrentItem”，有时幻灯片会在过渡过程中卡住，如下图所示。
演示活动
myViewPager2.setOrientation(ViewPager2.ORIENTATION_HORIZONTAL);
myViewPager2.setAdapter(myAdapter);
myViewPager2.setOffscreenPageLimit(3);
myViewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
super.onPageScrolled(position, positionOffset, positionOffsetPixels);
if (mLoadedFragment != null) {
mLoadedFragment.pauseMedia();
}
}
@Override
public void onPageSelected(int position) {
super.onPageSelected(position);
try {
rvSlideIndex.invalidate();
adapterSlideIndex.updateSelectedSlide(position);
//setTitle(mSlides.get(position).getTitle());
setScreenTitle(mSlides.get(position).getTitle());
mLoadedFragment = ((PresentationSlideFragment) myAdapter.createFragment(position));
mLoadedFragment.startVideo();
} catch (Exception e) {
}
}
@Override
public void onPageScrollStateChanged(int state) {
super.onPageScrollStateChanged(state);
if (mLoadedFragment != null && state == ViewPager2.SCROLL_STATE_SETTLING) {
mLoadedFragment.clearMediaPlayer();
}
}
});
public void onClick(final int position) {
drawerLayout.closeDrawer(GravityCompat.START);
//myAdapter.notifyDataSetChanged();
myViewPager2.postDelayed(new Runnable() {
@Override
public void run() {
myViewPager2.setCurrentItem(position); <--- **Here is problem**
}
}, 200);
}
演示活动 xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<!-- Layout to contain contents of main body of screen (drawer will slide over this) -->
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!-- Container for contents of drawer - use NavigationView to make configuration easier -->
<com.google.android.material.navigation.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true">
<androidx.recyclerview.widget.RecyclerView
android:layout_marginTop="80dp"
android:id="@+id/rl_slide_index"
android:layout_width="280dp"
android:layout_height="wrap_content" />
</com.google.android.material.navigation.NavigationView>
</androidx.drawerlayout.widget.DrawerLayout>
ViewPagerAdapter
import androidx.viewpager2.adapter.FragmentStateAdapter;
public class ViewPagerFragmentAdapter extends FragmentStateAdapter {
private ArrayList<Fragment> slides = new ArrayList<>();
public ViewPagerFragmentAdapter(@NonNull FragmentActivity fragmentActivity) {
super(fragmentActivity);
}
public void addFragment(Fragment fragment) {
slides.add(fragment);
}
@Override
public int getItemCount() {
return slides.size();
}
@NonNull
@Override
public Fragment createFragment(int position) {
return slides.get(position);
}
}
幻灯片片段
public class PresentationSlideFragment extends Fragment {
// Class variables and constructors
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout containing a title and body text.
ViewGroup rootView = (ViewGroup) inflater
.inflate(R.layout.fragment_slide, container, false);
String slideId = getArguments().getString("slideId", null);
if (slideId != null) {
mPresentationSlide = PresentationSlideData.getSlideById(slideId);
mTvtitle = rootView.findViewById(R.id.tv_title);
linearLayout = rootView.findViewById(R.id.linear);
videoView = rootView.findViewById(R.id.videoView);
videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
ViewGroup.LayoutParams lp = videoView.getLayoutParams();
lp.height = ViewGroup.LayoutParams.WRAP_CONTENT;
videoView.setLayoutParams(lp);
}
});
videoView.postDelayed(new Runnable() {
@Override
public void run() {
videoView.setVideoURI(Uri.parse("android.resource://com.ts.appname/" + mPresentationSlide.getVideo()));
}
}, 50);
//mMediaController = new MediaController(getContext());
//videoView.setMediaController(mMediaController);
// Binded text here---
}
return rootView;
}
@Override
public void onResume() {
super.onResume();
startVideo();
}
@Override
public void onPause() {
super.onPause();
pauseMedia();
}
public MediaController getMediaController() {
return mMediaController;
}
public MediaController startVideo() {
try {
videoView.postDelayed(new Runnable() {
@Override
public void run() {
try {
videoView.start();
mMediaController.hide();
} catch (Exception e) {
e.printStackTrace();
}
}
}, 0);
} catch (Exception e) {
e.printStackTrace();
}
return mMediaController;
}
@Override
public void onDestroy() {
super.onDestroy();
clearMediaPlayer();
}
public void clearMediaPlayer() {
videoView.stopPlayback();
}
public void pauseMedia() {
if (videoView != null && videoView.isPlaying()) {
videoView.pause();
}
}
}
幻灯片片段 xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:id="@+id/rl_video_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<VideoView
android:foregroundGravity="center"
android:id="@+id/videoView"
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_gravity="center" />
<FrameLayout
android:id="@+id/controllerAnchor"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/videoView" />
</RelativeLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="20dp"
android:layout_marginTop="-10dp"
android:layout_below="@id/rl_video_container"
android:background="@drawable/rounded_top_gray_card_border"
android:orientation="vertical">
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:layout_marginBottom="5dp"
android:textColor="@color/colorPrimary"
android:fontFamily="@font/fs_joey_bold"
android:textStyle="bold"
android:textSize="22dp" />
<LinearLayout
android:id="@+id/linear"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:orientation="vertical"></LinearLayout>
</LinearLayout>
</RelativeLayout>
发生此问题时收到的警告
V/MediaPlayer: cleanDrmObj: mDrmObj=null mDrmSessionId=null V/MediaPlayer: resetDrmState: mDrmInfo=null mDrmProvisioningThread=null mPrepareDrmInProgress=false mActiveDrmScheme=false V/MediaPlayer: cleanDrmObj: mDrmObj=null mDrmSessionId=null V/MediaPlayer: resetDrmState: mDrmInfo= null mDrmProvisioningThread=null mPrepareDrmInProgress=false mActiveDrmScheme=false V/MediaPlayer: cleanDrmObj: mDrmObj=null mDrmSessionId=null
W/View: requestLayout() improperly called by androidx.recyclerview.widget.RecyclerView{2ccd53e VFED..... ......ID 0,160-560,1424 #7f0a009d app:id/rl_slide_index} during layout: running second layout pass
W/View: requestLayout() improperly called by androidx.appcompat.widget.AppCompatTextView{623df9f V.ED..... ......ID 68,0-555,49 #7f0a002d app:id/action_bar_title} during layout: running second layout pass
感谢所有提高代码质量或应用程序性能的建议:)