android - 使用 Dagger 注入(inject) RecyclerView.Adapter

Question

我正在尝试将 RecyclerView 适配器注入(inject)到 Activity 中，但我没有得到预期的结果。该列表未被填充。

This is my adapter implementation:

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ListItemViewHolder> {

private TopMoviesActivityMVP.Presenter presenter;

public ListAdapter(TopMoviesActivityMVP.Presenter presenter) {
    this.presenter = presenter;
}

@NonNull
@Override
public ListAdapter.ListItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_movie_list, parent, false);
    return new ListItemViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull ListAdapter.ListItemViewHolder holder, int position) {
    presenter.bindRowViewAtPosition(holder, position);
}

@Override
public int getItemCount() {
    return presenter.getRowsCount();
}

public static class ListItemViewHolder extends RecyclerView.ViewHolder implements TopMoviesRowView {

    @BindView(R.id.tv_task_name)
    TextView tvName;
    @BindView(R.id.tv_task_country)
    TextView tvCountry;

    public ListItemViewHolder(View itemView) {
        super(itemView);
        ButterKnife.bind(this, itemView);
    }

    @Override
    public void setName(String name) {
        tvName.setText(name);
    }

    @Override
    public void setCountry(String country) {
        tvCountry.setText(country);
    }

}}

如您所见，适配器接收到 presenter 的实例，该实例用于访问下载的数据。在我的 activity 中，我正在尝试注入(inject) adapter:

public class TopMoviesActivity extends AppCompatActivity implements TopMoviesActivityMVP.View {

@BindView(R.id.list_activity_rootview)
ViewGroup rootView;
@BindView(R.id.recycler_view)
RecyclerView recyclerView;

@Inject
TopMoviesActivityMVP.Presenter presenter;
@Inject
RecyclerView.Adapter<ListAdapter.ListItemViewHolder> listAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_top_movies);

    ((App)getApplication()).getComponent().inject(this);

    ButterKnife.bind(this);
}

@Override
protected void onPostCreate(@Nullable Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    recyclerView.setAdapter(listAdapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
}

@Override
protected void onResume() {
    super.onResume();
    presenter.setView(this);
    presenter.loadData();
}

@Override
protected void onDestroy() {
    super.onDestroy();
    presenter.rxUnsubscribe();
}

@Override
public void updateData() {
    int count = presenter.getRowsCount();
    if (count == 0) {
        listAdapter.notifyItemInserted(0);
    } else {
        listAdapter.notifyItemInserted(count-1);
    }
}

@Override
public void showSnackbar(String msg) {
    Snackbar.make(rootView, msg, Snackbar.LENGTH_SHORT).show();
}}

即使在下载数据可用后调用 listAdapter.notifyItemInserted，也不会调用 onCreateViewHolder。

如果我不注入(inject)适配器，一切都会按预期工作:

@Override
protected void onPostCreate(@Nullable Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    listAdapter = new ListAdapter(presenter);
    recyclerView.setAdapter(listAdapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
}

This is my module:

@Module
public class TopMoviesModule {

@Provides
public RecyclerView.Adapter<ListAdapter.ListItemViewHolder> providesAdapter(TopMoviesActivityMVP.Presenter presenter) {
    return new ListAdapter(presenter);
}

@Provides
public TopMoviesActivityMVP.Presenter providesTopMoviesPresenter(TopMoviesActivityMVP.Model model) {
    return new TopMoviesPresenter(model);
}

@Provides
public TopMoviesActivityMVP.Model providesTopMoviesModel(Repository repository) {
    return new TopMoviesModel(repository);
}

@Provides
@Singleton
public Repository providesRepository(MoviesApiService moviesApiService, CountryApiService countryApiService) {
    return new TopMoviesRepository(moviesApiService, countryApiService);
}}

我不知道我错过了什么。

Answer 1

我认为这是因为作用域，问题是因为 Presenter 没有附加范围，所以您在 Activity 和适配器中获得了 Presenter 的 2 个不同实例。您可以通过在代码中添加断点来确认这一点。

此外，拥有一个与应用程序范围绑定(bind)的单例范围演示器也是非常错误的。

我建议为您的 Activity 使用一个具有自定义范围的子组件，这样它就不会比 Activity 长寿，并且您可以将适配器和演示者的范围限定到该 Activity。

有关 Dagger 子组件的更多信息，请查看此 link