我正在使用android分页库,但不是以块的形式获取数据,而是一次性获得完整的列表

Question

ViewModel类,我们在其中使用数据源加载pagedlist.

    public class RecipeListViewModel extends ViewModel {

    public LiveData<PagedList<RecipeListPojo>> mutableLiveData;

    public void init(RecipeFrom recipeFrom, RecipeDao recipeDao) {
    mutableLiveData = new 
    LivePagedListBuilder(recipeDao.getRecipeList(),10).build();
   }
   }

这是我的dao,我们以数据源工厂的形式获取数据.

   @Dao
   public interface RecipeDao {
   @Query("select * from recipe")
   public DataSource.Factory<Integer, RecipeListPojo> getRecipeList();
   }

在我的RecipeListPojo里面,我创建了DiffCallBack.

   public static DiffUtil.ItemCallback<RecipeListPojo> diffCallback=new 
   DiffUtil.ItemCallback<RecipeListPojo>() {
   @Override
   public boolean areItemsTheSame(RecipeListPojo oldItem, RecipeListPojo 
   newItem) {
   return oldItem.getId()==newItem.getId();
   }

   @Override
   public boolean areContentsTheSame(RecipeListPojo oldItem, RecipeListPojo 
   newItem) {
   return oldItem.equals(newItem);
   }
   };

在我的活动中,我通过观察者和设置我的适配器来回收页面列表.

  arrayListObserver=new Observer<PagedList<RecipeListPojo>>() {
  @Override
  public void onChanged(@Nullable PagedList<RecipeListPojo> recipePojos) {

  if(recipePojos!=null)
  {
  recipeAdapter.submitList(recipePojos);
  recyclerView.setAdapter(recipeAdapter);
  progressBar.setVisibility(GONE);
  }
  }
  };
  recipeFrom=new RecipeFrom.RecipeFromBuilder(fromActivity).build();
  recipeDao=GlobalApplication.recipeRoomDatabase.getRecipeDao();
  recipeListViewModel.init(recipeFrom,recipeDao);
  recipeListViewModel.mutableLiveData.observe(this,arrayListObserver);

这就是我的适配器的样子.

  public class RecipeListAdapter extends 
  PagedListAdapter<RecipeListPojo,RecipeListAdapter.RecipeListHolder> {

  private LayoutInflater inflater;
  private Context context;

  public RecipeListAdapter()
  {
  super(RecipeListPojo.diffCallback);
  }

  @Override
  public RecipeListHolder onCreateViewHolder(ViewGroup parent, int viewType) 
  {

  context=parent.getContext();
  inflater=LayoutInflater.from(context);
  View rootView = inflater.inflate(R.layout.one_item_recipe_list, null, 
  false);
  return new RecipeListHolder(rootView);
  }

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

图书馆使用 -

  // Paging
  implementation "android.arch.paging:runtime:1.0.0-rc1"

Answer 1

根据我的研究，我终于发现它返回一个大小=总数的列表。的项目，但只有 pagedList size * 3 将被初始化，其余项目将为空，并且它们将在使用 PagedListAdapter 滚动 recyclerView 时更新。