android - 在 Google Paging Library 3 中没有任何滚动的情况下，Api 调用不会一次又一次地停止调用

Question

我想实现分页以在我的应用程序中显示我想要的项目 View 的一大块列表。这就是为什么我选择使用谷歌新发布的分页库，即分页库 3。我在我的应用程序中使用 Rxjava、Livedata 和 ViewModel。
实现分页库后，我面临一个奇怪的问题。当我调用获取列表的方法时，它一次又一次地调用并且没有停止调用。事实上，虽然我没有滚动列表，但它会自动增加页码。
这是我尝试过的代码JobListRestApi.kt

interface JobListRestApi {
    @GET("job/list")
    fun getJobResponse(
        @Query("page") pageNumber: Int
    ): Single<Response<JobResponse>>
}

JobListDataSource.kt

class JobListDataSource @Inject constructor(
    private val jobListRestApi: JobListRestApi
): RxPagingSource<Int, Job>() {

    override fun loadSingle(params: LoadParams<Int>): Single<LoadResult<Int, Job>> {
        val position = params.key ?: 1

        return jobListRestApi.getJobResponse(position).toSingle()
            .subscribeOn(Schedulers.io())
            .map { jobResponse -> jobResponse.jobData.jobs }
            .map { jobs -> toLoadResult(jobs, position) }
            .onErrorReturn { LoadResult.Error(it) }
    }

    private fun toLoadResult(data: ArrayList<Job>, position: Int): LoadResult<Int, Job> {
        val prevKey = if (position == 1) null else position-1
        val nextKey = if (position == data.size) null else position+1

        return LoadResult.Page(data, prevKey, nextKey)
    }

}

JobListRepositoryImpl.kt

class JobListRepositoryImpl @Inject constructor(
    private val jobListDataSource: JobListDataSource
): JobListRepository {

    override fun getJobs(): Flowable<PagingData<Job>> {
        return Pager(PagingConfig(pageSize = 20)) {
            jobListDataSource
        }.flowable
    }
}

JobListViewModel.kt

class JobListViewModel @Inject constructor(
    private val jobListRepository: JobListRepository
): BaseViewModel() {

    val jobs: MutableLiveData<PagingData<Job>> = MutableLiveData()

    fun getJobs() {
        if (jobs.value == null) {
            compositeDisposable += jobListRepository.getJobs()
                .subscribe({
                    jobs.value = it
                }, {
                    handleException(it)
                })
        }
    }

}

JobListFragment.kt

class JobListFragment : BaseFragment<JobListViewModel>() {

    private val jobAdapter: JobAdapter by lazy {
        JobAdapter { }
    }

    override fun getLayoutResource() = R.layout.fragment_job_list

    override fun initWidget() {
        job_recycler_view.adapter = jobAdapter
    }

    override fun onResume() {
        super.onResume()
        viewModel.getJobs()
    }

    override fun observeLiveData() {
        observe(viewModel.jobs) {
            jobAdapter.submitData(lifecycle, it)
        }
    }
}

输出日志是
https://base-url/job/list?page=1
https://base-url/job/list?page=2
https://base-url/job/list?page=3
https://base-url/job/list?page=4
https://base-url/job/list?page=5
https://base-url/job/list?page=6
https://base-url/job/list?page=7
除非我转到 RecyclerView 中 block 的最后一项并滚动列表，否则如何停止调用串行 api

Answer 1

您通过返回 null 告诉 Paging 没有更多要加载的内容了。对于 prevKey和 nextKey在 LoadResult.Page由于它无限附加，看起来你从未设置 nextKey至null .也许您打算检查 data.isEmpty()而不是 key == data.size ?