android - 带分页库的无尽 RecyclerView 中的 AdMob 广告

Question

我正在使用paging library为了从服务器获取数据，我正在考虑每 10 个项目后显示广告。因此，当用户向下滚动时，就会获取新项目并将其添加到 PagedList 中。我希望新广告能够加载并添加到 RecyclerView 中，就像 Instagram 在 Feed 中显示广告一样。因此，如果用户滚动到 200 个项目，将逐渐显示 20 个广告!我已经阅读了一些教程，但我还没有找到一个简单的方法来做到这一点。

这是我的适配器。

class RequestsPagedAdapter(
        private val retryCallback: () -> Unit, private val from: From)
    : PagedListAdapter<RequestsQuery.Request, RecyclerView.ViewHolder>(POST_COMPARATOR) {
    private var networkState: NetworkState? = null

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        when (getItemViewType(position)) {
            R.layout.z_request_item -> (holder as RequestViewHolder).bind(getItem(position)!!, from)
            R.layout.network_state_item -> (holder as NetworkStateItemViewHolder).bindTo(networkState)
            R.layout.ad_admob_banner -> (holder as AdMobViewHolder)
        }
    }

    override fun onBindViewHolder(
            holder: RecyclerView.ViewHolder,
            position: Int,
            payloads: MutableList<Any>) {
        if (payloads.isNotEmpty()) {
            val item = getItem(position)
            (holder as RequestViewHolder).updateProduct(item!!)
        } else {
            onBindViewHolder(holder, position)
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return when (viewType) {
            R.layout.z_request_item -> RequestViewHolder.create(parent)
            R.layout.network_state_item -> NetworkStateItemViewHolder.create(parent, retryCallback)
            R.layout.ad_admob_banner -> AdMobViewHolder.create(parent)
            else -> throw IllegalArgumentException("unknown view type $viewType")
        }
    }

    private fun hasExtraRow() = networkState != null && networkState != NetworkState.LOADED

    override fun getItemViewType(position: Int): Int {
        return when {
            hasExtraRow() && position == itemCount - 1 -> R.layout.network_state_item
            position % ITEMS_PER_AD == 0 + 2 -> R.layout.ad_admob_banner
            else -> R.layout.z_request_item
        }
    }

    override fun getItemCount(): Int {
        return super.getItemCount() + if (hasExtraRow()) 1 else 0
    }

    fun setNetworkState(newNetworkState: NetworkState?) {
        val previousState = this.networkState
        val hadExtraRow = hasExtraRow()
        this.networkState = newNetworkState
        val hasExtraRow = hasExtraRow()
        if (hadExtraRow != hasExtraRow) {
            if (hadExtraRow) {
                notifyItemRemoved(super.getItemCount())
            } else {
                notifyItemInserted(super.getItemCount())
            }
        } else if (hasExtraRow && previousState != newNetworkState) {
            notifyItemChanged(itemCount - 1)
        }
    }

    companion object {
        val POST_COMPARATOR = object : DiffUtil.ItemCallback<RequestsQuery.Request>() {
            override fun areContentsTheSame(oldItem: RequestsQuery.Request, newItem: RequestsQuery.Request): Boolean =
                    oldItem == newItem

            override fun areItemsTheSame(oldItem: RequestsQuery.Request, newItem: RequestsQuery.Request): Boolean =
                    oldItem.id() == newItem.id()
        }
    }
}

这就是数据从 Fragment 提交到 PagedList 的方式。

private fun getRequests() {
    subcategoryRequestsListViewModel.requests.observe(viewLifecycleOwner, Observer {
        adapter.submitList(it)
    })
    subcategoryRequestsListViewModel.networkState.observe(viewLifecycleOwner, Observer {
        adapter.setNetworkState(it)
    })
}

和ViewHolder

class AdMobViewHolder(view: View) : RecyclerView.ViewHolder(view) {
    companion object {
        fun create(parent: ViewGroup): AdMobViewHolder {
            val view = LayoutInflater.from(parent.context)
                    .inflate(R.layout.ad_admob_banner, parent, false)
            return AdMobViewHolder(view)
        }
    }
}

Answer 1

没有比 google example here 更简单的例子了唯一的区别是，它从以原始格式保存的 XML 文件中获取数据，而您则从其他地方获取数据。我希望您可以根据您的需要轻松修改此示例。