Question

我有像这样的ViewPagerAdapter

public class ViewPagerAdapter extends FragmentStatePagerAdapter {
    List<MovieCategory> movieCategoryList;

    public ViewPagerAdapter(FragmentManager fm, List<MovieCategory> movieCategoryList) {
        super(fm);
        this.movieCategoryList = movieCategoryList;
    }

    @Override
    public Fragment getItem(int position) {

        return MoviePagerFragment.start(movieCategoryList, position, "listing");

    }

    @Override
    public int getCount() {
        return movieCategoryList.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return movieCategoryList.get(position).getCategoryTitle();

    }
}

此ViewPagerAdapter在MoviePagerFragment类中使用此静态方法调用MoviePagerFragment

public static Fragment start(List<MovieCategory> movieCategoryList, int position, String from) {
    Fragment moviePagerFragment = new MoviePagerFragment();
    Bundle basket = new Bundle();
    basket.putString("from",from);
    basket.putInt("viewpager-position",position);
    basket.putParcelableArrayList("movie_category_list", (ArrayList<? extends Parcelable>) movieCategoryList);
    basket.putParcelableArrayList("movie_list", (ArrayList<? extends Parcelable>) movieCategoryList.get(position).getMovies());
    moviePagerFragment.setArguments(basket);
    return moviePagerFragment;
}

现在我在MoviePagerFragment

中注册/取消注册EventBus

@Override
public void onStart() {
    super.onStart();
    EventBus.getDefault().register(this);
}

@Override
public void onStop() {
    super.onStop();
    EventBus.getDefault().unregister(this);
}

然后我有一个方法来订阅像这样发送的事件

@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessageEvent(final MovieBuyEvent event) {
    final double moviePrice = Double.parseDouble(event.getMoviesItem().getMoviePrice());
    final Dialog dialog = new Dialog(getActivity());
    dialog.setContentView(R.layout.channel_buy_dialog);
    dialog.setCancelable(true);
    ImageView imageView = (ImageView) dialog.findViewById(R.id.imageView);
    TextView tvName = (TextView) dialog.findViewById(R.id.tvName);
    Button bBuy = (Button) dialog.findViewById(R.id.bBuy);
    Button bCancel = (Button) dialog.findViewById(R.id.bCancel);
    final TextView tvPrice = (TextView) dialog.findViewById(R.id.tvPrice);
    final Spinner spinner = (Spinner) dialog.findViewById(R.id.spinner);
    Picasso.with(getActivity()).load(event.getMoviesItem().getMoviePicture()).placeholder(R.mipmap.placeholder).into(imageView);
    tvName.setText(event.getMoviesItem().getMovieName());
    tvPrice.setText(event.getMoviesItem().getMovieName());
    dialog.show();
}

正在通过RecyclerViewAdapter的ViewHolder类中的项目的ItemClick广播MovieBuyEvent

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    public ViewHolder(View view) {
        super(view);
        itemView.setClickable(true);
        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        position = getAdapterPosition();
        MoviesItem moviesItem = moviesItemList.get(position);
        try {
            MovieBuyEvent movieBuyEvent = new MovieBuyEvent();
                movieBuyEvent.setMoviesItem(moviesItem);
                EventBus.getDefault().post(movieBuyEvent);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

现在的问题是，每次刷一个片段时，EventBus都会多次注册和取消注册

onMessageEvent（最终的MovieBuyEvent事件）

方法也被调用多次使Dialog出现多次。那么我应该在ViewPagerAdapter调用的片段中注册/取消注册EventBus？

Answer 1

如果您有多个注册过来监听MovieBuyEvent广播的片段，他们都会回复，这是有道理的。如果您在包含可解决问题的viewpager的活动或片段中注册了您的事件监听器。

Answer 2

您应该将注册活动从onStart()移至onCreateView()。这是因为onStart总是called when the Fragment is visible to the user。

然后尝试取消注册onDestroy()：

@Override
public void onDestroy() {
    super.onDestroy();
    EventBus.getDefault().unregister(this);
}

Answer 3

如果您从未在viewpager中使用过setOffscreenPageLimit，则应限制为1。默认情况下，viewpager正在加载当前打开父片段/活动时看到的三个片段，另外两个片段。在初始化viewpager时尝试将setOffscreenPageLimit设置为1。基本上它会一次加载一个片段而不是每个viewpager滚动三个。当您使用事件总线时，它一次只能获得一个片段而不是所有正在使用的片段。

EventBus在ViewPager Fragment中多次调用

3 个答案: