我遇到了一个问题，即每次系统从服务中进行更新时，新物品都会放在回收者所在的物品之前。这意味着它将始终处于“终点”。我正在使用PagedList.BoundaryCallback库，但不知道要修复此问题。
这是我的RepoBoundaryCalback
class RepoBoundaryCallback(private val day:String,
private val service: PHService,
private val cache:PHLocalCache) : PagedList.BoundaryCallback<Post>() {
// keep the last requested page.
// When the request is successful, increment the page number.
private var lastRequestedPage = 1
private val _networkErrors = MutableLiveData<String>()
// LiveData of network errors.
val networkErrors: LiveData<String>
get() = _networkErrors
// avoid triggering multiple requests in the same time
private var isRequestInProgress = false
/**
* This method is called at the very beggining
*/
override fun onZeroItemsLoaded() {
requestAndSaveData()
}
/**
* This method will tell when the user reached the end of the recycler view
*/
override fun onItemAtEndLoaded(itemAtEnd: Post) {
requestAndSaveData()
//TODO resolver este bug
//ele aqui sabe que chegou ao fim , o problema desta API é que nao dá o total de páginas
// e quando ultrapassa as paginas que deve ela dá dados repetidos
// como o onConflit está replace ele está sempre a substituir os items e sempre a actualizar
}
/**
* Requests data from the API and increment the page in case of success
* Save the fetched data into the database to allow offline usage
*/
private fun requestAndSaveData(){
//TODO ao atingir o total de páginas o isRequestInProgress estará a null(o problema de estar sempre a actualizar vem daqui)
if (isRequestInProgress) return
isRequestInProgress = true
getPosts(service,day,lastRequestedPage,BuildConfig.API_KEY, NETWORK_PAGE_SIZE,{ repos ->
cache.insert(repos){
lastRequestedPage++
isRequestInProgress = false
}
},{error ->
_networkErrors
isRequestInProgress = false
})
}
/**
* static block to have the page size to the network calls
*/
companion object {
private const val NETWORK_PAGE_SIZE = 10
}
}
这是我的PostDao，因为我认为订购这些商品应该可以解决
@Dao
interface PostDao {
@Query("SELECT * FROM product_post ORDER BY votesCount DESC, productName ASC")
fun loadPosts() : DataSource.Factory<Int,Post>
@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertAll(message: List<Post>)
}
这是我的存储库
class PHRepository (private val service:PHService,
private val cache: PHLocalCache) {
/**
* Search repositories whose names match the query.
*/
fun search(day: String): PostResult {
// Get data source factory from the local cache
val dataSourceFactory = cache.loadPosts(day)
// Construct the boundary callback
val boundaryCallback = RepoBoundaryCallback(day, service,cache)
val networkErrors = boundaryCallback.networkErrors
// Get the paged list
val data = LivePagedListBuilder(dataSourceFactory, DATABASE_PAGE_SIZE)
.setBoundaryCallback(boundaryCallback)
.build()
// Get the network errors exposed by the boundary callback
return PostResult(data)
}
companion object {
private const val DATABASE_PAGE_SIZE = 20
}
}
这是我的ViewModel
class PostsViewModel @Inject constructor(private val phRepository: PHRepository) : ViewModel() {
companion object {
private const val VISIBLE_THRESHOLD = 5
}
private val queryLiveData = MutableLiveData<String>()
private val repoResult: LiveData<PostResult> = Transformations.map(queryLiveData, {
phRepository.search(it)
})
val repos: LiveData<PagedList<Post>> = Transformations.switchMap(repoResult,
{ it -> it.data })
/**
* Search a repository based on a query string.
*/
fun searchRepo(queryString: String) {
queryLiveData.postValue(queryString)
}
/**
* Get the last query value.
*/
fun lastQueryValue(): String? = queryLiveData.value
}
这是我的片段
class PostFragment : BaseFragment<FragmentPostsBinding, PostsViewModel>() {
companion object {
fun newInstance() = PostFragment()
}
private lateinit var viewModelFrag :PostsViewModel //TODO nao foi inicializado
private val adapter = PostAdapter()
override fun layoutToInflate(): Int = R.layout.fragment_posts
override fun defineViewModel(): PostsViewModel {
// get the view model
viewModelFrag = ViewModelProviders.of(this, Injection.provideViewModelFactory(context))
.get(PostsViewModel::class.java)
return viewModelFrag
}
override fun doOnCreated() {
initAdapter()
retrieveData()
}
private fun initAdapter() {
dataBinding.rclChatContent.adapter = adapter
viewModelFrag.repos.observe(this, Observer<PagedList<Post>> {
Log.d("Activity", "list: ${it?.size}")
adapter.submitList(it)
})
dataBinding.rclChatContent.layoutManager = LinearLayoutManager(context)
dataBinding.rclChatContent.addOnItemTouchListener(OnItemTouchListener(context,dataBinding.rclChatContent,
object : TouchListener {
override fun onTouch(view: View?, position: Int?) {
val item = adapter.retrieveItem(position?:return)
Toast.makeText(context, "Clicou em" + item?.productName , Toast.LENGTH_LONG).show()
}
override fun onLongTouch(view: View?, position: Int?) {
val item = adapter.retrieveItem(position?:return)
Toast.makeText(context, "Clicou longo em" + item?.productName, Toast.LENGTH_LONG).show()
}
}))
}
private fun retrieveData() {
viewModelFrag.searchRepo("2018-07-31")
adapter.submitList(null)
}
}
由于有人遇到这个问题，我们可以帮助我吗？