Android：Paging3：重复项

如何解决Android：Paging3：重复项

问题： 我从列表的开头得到40个项目，然后从11开始计数，此后一切都很好。所以，... 1 ... 40,11,12,13，...，300。

当我滚动很多到底部然后向上滚动以查看第一个项目时，这些项目已更改为1,2，...，10,1,2 ，...，10,12，...，300。

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但是，当我在false中将enablePlaceholders传递到PagingConfig时，当我滚动到底部时，我看到了如上所述的问题（1,2，.. 40， 11， ...，300），然后这40个项目突然消失，我只看到1,2，...，10 + 11 ，12，.. 。，300（正确的方法）;而且它不会改变或变得更糟。

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ProductsPagingSource ：

@Singleton
class ProductsPagingSource @Inject constructor(
    private val productsApi: ProductsApi
    //private val query: String
) : RxPagingSource<Int,RecyclerItem>() {

    override fun loadSingle(params: LoadParams<Int>): Single<LoadResult<Int,RecyclerItem>> {
        val position = params.key ?: STARTING_PAGE_INDEX
        //val apiQuery = query

        return productsApi.getBeersList(position,params.loadSize)
            .subscribeOn(Schedulers.io())
            .map { listBeerResponse ->
                listBeerResponse.map { beerResponse ->
                    beerResponse.toDomain()
                }
            }
            .map { toLoadResult(it,position) }
            .onErrorReturn { LoadResult.Error(it) }
    }

    private fun toLoadResult(
        @NonNull response: List<RecyclerItem>,position: Int
    ): LoadResult<Int,RecyclerItem> {
        return LoadResult.Page(
            data = response,prevKey = if (position == STARTING_PAGE_INDEX) null else position - 1,nextKey = if (response.isEmpty()) null else position + 1,itemsBefore = LoadResult.Page.COUNT_UNDEFINED,itemsAfter = LoadResult.Page.COUNT_UNDEFINED
        )
    }

}

ProductsListRepositoryImpl ：

@Singleton
class ProductsListRepositoryImpl @Inject constructor(
    private val pagingSource: ProductsPagingSource
) : ProductsListRepository {

    override fun getBeers(ids: String): Flowable<PagingData<RecyclerItem>> = Pager(
        config = PagingConfig(
            pageSize = 10,enablePlaceholders = true,maxSize = 30,prefetchDistance = 5,initialLoadSize = 40
        ),pagingSourceFactory = { pagingSource }
    ).flowable

}

ProductsListViewModel ：

class ProductsListViewModel @ViewModelInject constructor(
    private val getBeersUseCase: GetBeersUseCase
) : BaseViewModel() {

    private val _ldProductsList: MutableLiveData<PagingData<RecyclerItem>> = MutableLiveData()
    val ldProductsList: LiveData<PagingData<RecyclerItem>> = _ldProductsList

    init {
        loading(true)
        getProducts("")
    }

    private fun getProducts(ids: String) {
        loading(false)
        getBeersUseCase(GetBeersParams(ids = ids))
            .cachedIn(viewModelScope)
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe {
                _ldProductsList.value = it
            }.addTo(compositeDisposable)
    }

}

ProductsListFragment ：

@AndroidEntryPoint
class ProductsListFragment : Fragment(R.layout.fragment_product_list) {

    private val productsListViewModel: ProductsListViewModel by viewModels()

    private val productsListAdapter: ProductsListAdapter by lazy {
        ProductsListAdapter(::navigateToProductDetail)
    }

    override fun onViewCreated(view: View,savedInstanceState: Bundle?) {
        super.onViewCreated(view,savedInstanceState)
        setupRecycler()
        setupViewModel()
    }

    private fun setupRecycler() {
        itemErrorContainer.gone()
        productListRecyclerView.adapter = productsListAdapter
    }

    private fun setupViewModel() {
        productsListViewModel.run {

            observe(ldProductsList,::addProductsList)

            observe(ldLoading,::loadingUI)

            observe(ldFailure,::handleFailure)

        }
    }

    private fun addProductsList(productsList: PagingData<RecyclerItem>) {
        loadingUI(false)
        productListRecyclerView.visible()
        productsListAdapter.submitData(lifecycle,productsList)
    }
...

BASE_DIFF_CALLBACK ：

val BASE_DIFF_CALLBACK = object : DiffUtil.ItemCallback<RecyclerItem>() {

    override fun areItemsTheSame(oldItem: RecyclerItem,newItem: RecyclerItem): Boolean {
        return oldItem.id == newItem.id
    }

    override fun areContentsTheSame(oldItem: RecyclerItem,newItem: RecyclerItem): Boolean {
        return oldItem == newItem
    }

}

BasePagedListAdapter ：

abstract class BasePagedListAdapter(
    vararg types: Cell<RecyclerItem>,private val onItemClick: (RecyclerItem,ImageView) -> Unit
) : PagingDataAdapter<RecyclerItem,RecyclerView.ViewHolder>(BASE_DIFF_CALLBACK) {

    private val cellTypes: CellTypes<RecyclerItem> = CellTypes(*types)

    override fun getItemViewType(position: Int): Int {
        getItem(position).let {
            return cellTypes.of(it).type()
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup,viewType: Int): RecyclerView.ViewHolder {
        return cellTypes.of(viewType).holder(parent)
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder,position: Int) {
        getItem(position).let {
            cellTypes.of(it).bind(holder,it,onItemClick)
        }
    }

}

解决方法

我必须为Declare @Object as Int; Declare @ResponseText as Varchar(8000); DECLARE @reqHead AS VARCHAR(8000) = '{ "x-authorization":"N2I2OWU2OTg0MmE0M2JkMmNhYmQyZjg1MDJjYWY1","Email":"[e-mail]","content-type":"application/json" }' DECLARE @Body AS VARCHAR(8000) = '{ "data": [ { "message_bag": { "numbers": "0700000000","message": "testing sms.","sender": "MY_SENDER_ID" } } ] }' ; -- Code Snippet MSXML2.ServerXMLHttp MSXML2.XMLHTTP Exec sp_OACreate 'MSXML2.ServerXMLHttp',@Object OUT; Exec sp_OAMethod @Object,'open',NULL,'post','https://mysmsprovider.co.ke/api/messaging','false' --select @reqHead Exec sp_OAMethod @Object,'setRequestHeader',@reqHead,'Content-Type','application/json' --select @body Exec sp_OAMethod @Object,'send',null,@body Exec sp_OAMethod @Object,'responseText',@ResponseText OUTPUT Select @ResponseText Exec sp_OADestroy @Object 和pageSize设置相同的数字。另外，我必须将initialLoadSize设置为enablePlaceholders。

false

但是，我还是想知道这是否正常吗？如果是的话，我找不到任何指向此的信息！如果没有，那为什么呢？为什么config = PagingConfig( pageSize = 10,enablePlaceholders = false,maxSize = 30,prefetchDistance = 5,initialLoadSize = 10 ),的价值不能超过initialLoadSize ？！ 如我们所见，pageSize的默认值为：

initialLoadSize