kotlin paging3 withLoadStateFooter
时间: 2023-12-22 20:25:04 浏览: 32
Kotlin Paging 3库提供了withLoadStateFooter函数,可以在分页数据的末尾添加一个“加载状态”footer。该函数需要一个LoadStateAdapter作为参数,用于管理不同的加载状态(如加载中、加载完成、加载失败等)。
示例代码如下:
```
val adapter = MyPagingAdapter()
val footer = MyLoadStateAdapter { adapter.retry() }
recyclerView.adapter = adapter.withLoadStateFooter(footer)
```
其中,MyLoadStateAdapter是自定义的LoadStateAdapter,retry()方法用于重试加载数据。
相关问题
kotlin paging3+recyclerview数据分页示例
以下是一个使用 Kotlin 和 Paging3+RecyclerView 实现数据分页的示例:
1. 首先,我们需要定义一个包含数据的列表和当前页码的类,使用 PagingData 类型:
```
data class Data(
val id: Int,
val name: String,
val description: String
)
```
2. 接下来,我们需要定义一个 PagingSource,它负责从数据源获取数据:
```
class DataPagingSource(private val api: DataApi) : PagingSource<Int, Data>() {
override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Data> {
try {
val page = params.key ?: 1
val pageSize = params.loadSize
val response = api.getData(page, pageSize)
val data = response.data
val prevKey = if (page == 1) null else page - 1
val nextKey = if (data.isEmpty()) null else page + 1
return LoadResult.Page(
data = data,
prevKey = prevKey,
nextKey = nextKey
)
} catch (e: Exception) {
return LoadResult.Error(e)
}
}
override fun getRefreshKey(state: PagingState<Int, Data>): Int? {
return state.anchorPosition?.let { anchorPosition ->
val anchorPage = state.closestPageToPosition(anchorPosition)
anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}
}
}
```
3. 然后,我们需要定义一个 PagingData 类型的数据流,并使用它创建一个 PagingDataAdapter:
```
class DataAdapter : PagingDataAdapter<Data, DataViewHolder>(DataDiffCallback) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): DataViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.item_data, parent, false)
return DataViewHolder(view)
}
override fun onBindViewHolder(holder: DataViewHolder, position: Int) {
val item = getItem(position)
holder.bindData(item)
}
object DataDiffCallback : DiffUtil.ItemCallback<Data>() {
override fun areItemsTheSame(oldItem: Data, newItem: Data): Boolean {
return oldItem.id == newItem.id
}
override fun areContentsTheSame(oldItem: Data, newItem: Data): Boolean {
return oldItem == newItem
}
}
}
```
4. 最后,在 Activity 或 Fragment 中使用 RecyclerView 和 DataAdapter:
```
class MainActivity : AppCompatActivity() {
private lateinit var recyclerView: RecyclerView
private lateinit var adapter: DataAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recyclerView = findViewById(R.id.recycler_view)
recyclerView.layoutManager = LinearLayoutManager(this)
adapter = DataAdapter()
recyclerView.adapter = adapter
val api = DataApi()
val pagingSourceFactory = { DataPagingSource(api) }
val pagingConfig = PagingConfig(pageSize = 10)
val dataFlow = Pager(
config = pagingConfig,
pagingSourceFactory = pagingSourceFactory
).flow
dataFlow.cachedIn(lifecycleScope).collectLatest { pagingData ->
adapter.submitData(pagingData)
}
}
}
```
这是一个简单的示例,你可以根据自己的需求进行修改和扩展。
kotlin paging3+retrofit2+recyclerview 代码示例
以下是一个Kotlin中使用Paging3、Retrofit2和RecyclerView的示例代码:
```kotlin
// 创建一个PagingConfig实例
val pagingConfig = PagingConfig(pageSize = 20, enablePlaceholders = false)
// 创建一个PagingSource实例
val myPagingSource = MyPagingSource(apiService)
// 创建一个Pager实例
val pager = Pager(pagingConfig, pagingSourceFactory = { myPagingSource })
// 创建一个LiveData实例
val myLiveData = pager.liveData.cachedIn(viewModelScope)
// 创建一个PagingDataAdapter实例
val myPagingDataAdapter = MyPagingDataAdapter()
// 绑定RecyclerView和PagingDataAdapter
myRecyclerView.adapter = myPagingDataAdapter
// 观察LiveData实例并更新PagingDataAdapter
myLiveData.observe(this) { pagingData ->
myPagingDataAdapter.submitData(lifecycle, pagingData)
}
```
其中,`MyPagingSource`是一个继承自`PagingSource<Int, MyData>`的类,用于从网络或本地数据库中获取数据。`MyPagingDataAdapter`是一个继承自`PagingDataAdapter<MyData, MyViewHolder>`的类,用于显示数据并处理分页。请根据自己的需要修改这些类的实现。