Android进阶：高仿抖音上下滑动分页视频，要求页面流畅

3.2 ViewPager和Fragment

• 采用了ViewPager+FragmentStatePagerAdapter+Fragment来处理。为何选择使用FragmentStatePagerAdapter，主要是因为使用 FragmentStatePagerAdapter更省内存，但是销毁后新建也是需要时间的。一般情况下，如果你是用于ViewPager展示数量特别多的条目时，那么建议使用FragmentStatePagerAdapter。关于PagerAdapter的深度解析，可以我这篇文章：PagerAdapter深度解析和实践优化
• 在activity中的代码如下所示

private void initViewPager() {
List list = new ArrayList<>();
ArrayList fragments = new ArrayList<>();
for (int a = 0; a< DataProvider.VideoPlayerList.length ; a++){
Video video = new Video(DataProvider.VideoPlayerTitle[a],
10,“”,DataProvider.VideoPlayerList[a]);
list.add(video);
fragments.add(VideoFragment.newInstant(DataProvider.VideoPlayerList[a]));
}
vp.setOffscreenPageLimit(1);
vp.setCurrentItem(0);
vp.setOrientation(DirectionalViewPager.VERTICAL);
FragmentManager supportFragmentManager = getSupportFragmentManager();
MyPagerAdapter myPagerAdapter = new MyPagerAdapter(fragments, supportFragmentManager);
vp.setAdapter(myPagerAdapter);
}

class MyPagerAdapter extends FragmentStatePagerAdapter{

private ArrayList list;

public MyPagerAdapter(ArrayList list , FragmentManager fm){
super(fm);
this.list = list;
}

@Override
public Fragment getItem(int i) {
return list.get(i);
}

@Override
public int getCount() {
return list!=null ? list.size() : 0;
}
}

• 那么在fragment中如何处理呢？关于视频播放器，这里可以看我封装的库，视频lib

public class VideoFragment extends Fragment{

public VideoPlayer videoPlayer;
private String url;
private int index;

@Override
public void onStop() {
super.onStop();
VideoPlayerManager.instance().releaseVideoPlayer();
}

public static Fragment newInstant(String url){
VideoFragment videoFragment = new VideoFragment();
Bundle bundle = new Bundle();
bundle.putString(“url”,url);
videoFragment.setArguments(bundle);
return videoFragment;
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle arguments = getArguments();
if (arguments != null) {
url = arguments.getString(“url”);
}
}

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_video, container, false);
return view;
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
videoPlayer = view.findViewById(R.id.video_player);
}