孟老板 ListAdapter封装, 告别Adapter代码 (四)

ListAdapter封装 (四) - 分页封装;

前言:

这是ListAdapter最后一篇了; 简单封装一下分页逻辑; 由于框架五花八门(网络请求, 下拉刷新, 加载更多等),这篇只做参照即可;

分析:

ViewModel 需要处理: 页码, 请求解析数据, 发送加载更多状态, 发送下拉刷新状态等;

View 需要处理: 初始化Adapter, RecycleView. 绑定加载更多控件, 监听下拉及加载更多状态等;

本篇用到的库:

//loadmore

implementation 'com.github.nukc:loadmorewrapper:1.8.3'

//retrofit 2.9 系列

implementation "com.squareup.retrofit2:retrofit:2.9.0"

//viewmodel

implementation "androidx.lifecycle:lifecycle-viewmodel:2.2.0"

implementation "androidx.lifecycle:lifecycle-livedata:2.2.0"

implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.2.0"

implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

1.BasePageModel;

它是分页 ViewModel 的基类. 使用 retrofit 拉取数据;

abstract class BasePageModel<T: BaseItem> (application: Application) : AndroidViewModel(application){

    private var pageInit = 1

    private var page = pageInit

    private var pageSize = 10

    private var maxPage: Int = 1

    /**

     * 下拉刷新状态,

     */

    var refreshEnabled: MutableLiveData<Boolean> = MutableLiveData(false)

    /**

     * 加载更多状态

     */

    var loadEnabled: MutableLiveData<Boolean> = MutableLiveData(true)

    /**

     * 列表数据

     */

    var listData: MutableLiveData<MutableList<T>> = MutableLiveData(mutableListOf())

    fun loadData(param: ArrayMap<String, Any>){

        param["page"] = page

        param["pageSize"] = pageSize

        //发起网络请求.

        retrofit<JsonObject>(viewModelScope) {

            onSuccess {

                disposeResp(it)

            }

            onFailed { msg, _ ->

                Toast.makeText(getApplication(), msg, Toast.LENGTH_SHORT).show()

            }

            onComplete {

                refreshEnabled.value = false

            }

            api = getResp(ApiManager.INSTANCE.getJsonBody(param))

        }

    }

    /**

     * 处理响应;

     * 1.解析响应数据;  2.获取总页码数;  3.拼接数据;

     * 4.页码++  5.判断loadMore Enabled  6.取消下拉刷新状态

     */

    private fun disposeResp(resp: BaseResp<JsonObject?>){

        val list = analysisData(resp.data) ?: mutableListOf()

        maxPage = resp.data?.asJsonObject?.get("totalPage")?.asInt ?: 1

        if (page == pageInit) {

            listData.value = list

        } else {

            val data = listData.value

            data?.addAll(list)

            listData.value = data

        }

        page++

        if (page > maxPage) {

            switchEnabled(false)

        } else {

            //数据够,则继续加载;  数据不够了,则关闭加载

            switchEnabled(list.size >= pageSize)

        }

    }

    /**

     * 切换 loadMore Enabled;

     */

    private fun switchEnabled(boolean: Boolean){

        if(boolean != loadEnabled.value){

            loadEnabled.value = boolean

        }

    }

    /**

     * 重新加载数据;

     */

    fun reload(){

        page = pageInit

        listData.value = mutableListOf()

        switchEnabled(true)

    }

    /**

     * 处理数据,  因服务器响应数据不规范,  只能用Json接收;

     * 可以省去  -  当响应数据可以直接解析为 实体集合时,

     */

    abstract fun analysisData(jo: JsonObject?): MutableList<T>?

    /**

     * retrofit API

     */

    abstract suspend fun getResp(rBody: RequestBody): BaseResp<JsonObject?>

}

2. ViewModel

它继承 BasePageModel;

class CheckModel(application: Application) : BasePageModel<CheckEntity>(application) {

    override fun analysisData(jo: JsonObject?): MutableList<CheckEntity>? {

        val str: String? = jo?.getAsJsonArray("newsList")?.toString()

        //将String 解析为 实体集合

        return str?.toBeanList()

    }

    override suspend fun getResp(rBody: RequestBody): BaseResp<JsonObject?> {

        return ApiManager.INSTANCE.mApi.getDynamicList(rBody)

    }

}

3. MyPageHelper

使用 loadmorewrapper 库加载更多; 监听数据, 监听状态都写在这个类里

class MyPageHelper(

    adapter: BaseAdapter<out BaseItem>,

    private val mRecycle: RecyclerView,

    private val pageModel: BasePageModel<out BaseItem>,

    /**

     * Activity 或 Fragment

     * 1. 提供 Lifecycle

     * 2. 提供 请求参数;  这里全是用 map -> JsonBody 方式提交参数;

     */

    private val mView: PagingView

) {

    private val mAdapter = adapter as BaseAdapter<BaseItem>

    private var mEnabled: LoadMoreAdapter.Enabled? = null

    fun load(){

        LoadMoreWrapper.with(mRecycle.adapter).apply{

            setShowNoMoreEnabled(true) // enable show NoMoreView，default false

            setListener { enabled: LoadMoreAdapter.Enabled ->

                mEnabled = enabled

                val param = ArrayMap<String, Any>()

                mView.prepareMap(param)

                pageModel.loadData(param)

            }

        }.into(mRecycle)

        // 数据变更时, 刷新列表

        pageModel.listData.observe(mView){

            mAdapter.submitList(it)

        }

        // 监听没有更多的状态;

        // 当页码超出, 或当前页数据不满一页时, 没有更多

        // 当页面下拉刷新时,重新启动 loadMore

        pageModel.loadEnabled.observe(mView){

            setEnabled(it)

        }

    }

    /**

     * 控制加载更多功能;  false: 显示没有更过;    true: 滚动到底时触发 loadMore

     */

    private fun setEnabled(enabled: Boolean) {

        mEnabled?.let {

            it.loadMoreEnabled = enabled

            if(enabled){

                mRecycle.adapter?.notifyItemChanged(mRecycle.adapter?.itemCount ?: 0)

            }

        }

    }

    /**

     * Activity 或 Fragment  需要实现它

     */

    interface PagingView : LifecycleOwner {

        /**

         * 绑定额外请求参数;

         */

        fun prepareMap(map: ArrayMap<String, Any>){}

    }

}

4.使用

需要实现 MyPageHelper.PagingView; 重写 prepareMap() 提供请求参数

然后初始化 Adapter, RecycleView, Helper;

下拉刷新, 也可以写在 Helper 中;

class CheckPageFragment : BaseMVVMFragment<CheckModel, LayoutRecycleBinding>(),

    MyPageHelper.PagingView {

    private lateinit var mAdapter: SingleChoiceAdapter<CheckEntity>

    private var mHelper: MyPageHelper? = null

    override fun getLayoutId(): Int = R.layout.layout_recycle

    override fun onLazyLoad() {

        //初始化 Adapter 及 RecycleView

        mAdapter = SingleChoiceAdapter(R.layout.item_test_choise)

        mDataBind.rvRecycle.let {

            it.layoutManager = LinearLayoutManager(mActivity)

            it.adapter = mAdapter

        }

        //初始化 Helper

        mViewModel?.let {

            mHelper = MyPageHelper(mAdapter, mDataBind.rvRecycle, it, this)

            mHelper?.load()

        }

        //swipeRefresh

        mDataBind.swipeRefresh.setOnRefreshListener {

            mViewModel?.reload()

        }

        mViewModel?.refreshEnabled?.observe(this){

            mDataBind.swipeRefresh.isRefreshing = it

        }

    }

}

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孟老板 ListAdapter封装, 告别Adapter代码 (四)

ListAdapter封装 (四) - 分页封装;

前言:

分析:

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