我有一个pagingsource如下所示：
class NotificationPagingSource(
private val tayehAPI: TayehAPI,
private val token: String,
) : PagingSource<Int, Notification>() {
override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Notification> {
val nextPageNumber = params.key ?: STARTING_PAGE_INDEX
return try {
val response = tayehAPI.getNotifications(
tokenString = token,
page = nextPageNumber,
perPage = params.loadSize
)
val notifications = response.objects
LoadResult.Page(
data = notifications,
prevKey = if (nextPageNumber == STARTING_PAGE_INDEX) null else nextPageNumber - 1,
nextKey = if (notifications.isEmpty()) null else nextPageNumber + 1
)
} catch (e: IOException) {
LoadResult.Error(e)
} catch (e: HttpException) {
LoadResult.Error(e)
}
}
override fun getRefreshKey(state: PagingState<Int, Notification>): Int? {
return state.anchorPosition?.let { anchorPosition ->
val anchorPage = state.closestPageToPosition(anchorPosition)
anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}
}
}
我想处理httpexceptions（如403或404）。我怎样才能做到这一点呢？
您需要将AddLoadStateListener添加到分页适配器，如下所示：
notificationAdapter.addLoadStateListener { loadState ->
val errorState = when {
loadState.append is LoadState.Error -> loadState.append as LoadState.Error
loadState.prepend is LoadState.Error -> loadState.prepend as LoadState.Error
loadState.refresh is LoadState.Error -> loadState.refresh as LoadState.Error
else -> null
}
errorState?.let {
if (errorState.error.localizedMessage == "HTTP 403 Forbidden") {
AlertDialog.Builder(requireContext())
.setMessage(R.string.token_expire)
.setPositiveButton("Ok") { _, _ ->
findNavController().navigate(
NotificationFragmentDirections.actionGlobalHomeFragment()
)
}
.setCancelable(false)
.create()
.show()
}
}
}
