Paging3分页加载
服务端是网上找的开源接口，来自：https://www.free-api.com/
最终效果
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引入依赖：
//Paging 3.0 implementation 'androidx.paging:paging-compose:1.0.0-alpha14' implementation "androidx.paging:paging-runtime-ktx:3.1.0-rc01" -
Paging实现分页加载，简单快捷可定制，内部管理了分页逻辑和异常处理，而分页规则需要自己定义。主要代码：
class ExamSource(private val repository: Repository) : PagingSource<Int, Question>() { private val TAG = "--ExamSource" override fun getRefreshKey(state: PagingState<Int, Question>): Int? { return null } override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Question> { return try { val currentPage = params.key ?: 1 val pageSize = params.loadSize Log.d(TAG, "currentPage: $currentPage") Log.d(TAG, "pageSize: $pageSize") // 传入当前页码，每页大小，然后请求数据。网络请求封装在repository val responseList = repository.getExamList(currentPage, pageSize = pageSize) .result?.resultData?.questionList ?: emptyList<Question>() // 加载分页 val everyPageSize = 4 val initPageSize = 8 // 前一页 val preKey = if (currentPage == 1) null else currentPage.minus(1) // 下一页 var nextKey: Int? = if (currentPage == 1) { initPageSize / everyPageSize } else { currentPage.plus(1) } Log.d(TAG, "preKey: $preKey") Log.d(TAG, "nextKey: $nextKey") if (responseList.isEmpty()) { nextKey = null } Log.d(TAG, "final nextKey: $nextKey") LoadResult.Page( data = responseList, prevKey = preKey, nextKey = nextKey ) } catch (e: Exception) { e.printStackTrace() LoadResult.Error(e) } } }
沉浸式状态栏
// 状态栏相关
implementation "com.google.accompanist:accompanist-insets:0.21.2-beta"
implementation "com.google.accompanist:accompanist-insets-ui:0.21.2-beta"
implementation "com.google.accompanist:accompanist-systemuicontroller:0.21.2-beta"
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WindowCompat.setDecorFitsSystemWindows(window, true)/** * 设置decorView是否适配windowsetscompat的WindowInsetsCompat根视图。 * 若置为false，将不适配内容视图的insets，只会适配内容视图。 * 请注意:在应用程序中使用View.setSystemUiVisibility(int) API可能会与此方法冲突。应停止使用View.setSystemUiVisibility(int)。 */ public static void setDecorFitsSystemWindows(@NonNull Window window, final boolean decorFitsSystemWindows) { if (Build.VERSION.SDK_INT >= 30) { Impl30.setDecorFitsSystemWindows(window, decorFitsSystemWindows); } else if (Build.VERSION.SDK_INT >= 16) { Impl16.setDecorFitsSystemWindows(window, decorFitsSystemWindows); } }- 状态栏透明
拿到SystemUiController的setStatusBarColor()方法来改变状态栏，也可以修改底部导航栏
setContent { UseComposeTheme { // 状态栏改为透明，参数：color(状态栏颜色)，darkIcons（是否为深色图标） rememberSystemUiController().setStatusBarColor( Color.Transparent, darkIcons = MaterialTheme.colors.isLight ) // 底部导航栏颜色 rememberSystemUiController().setNavigationBarColor( Color.Transparent, darkIcons = MaterialTheme.colors.isLight ) // ... } }- 调整以适配状态栏高度
需要用到ProvideWindowInsets，在显示内容的外围包一层ProvideWindowInsets，在Theme以下包裹ProvideWindowInsets以便取得状态栏的高度。
setContent { UseComposeTheme { // 加入ProvideWindowInsets ProvideWindowInsets { // 状态栏改为透明 rememberSystemUiController().setStatusBarColor( Color.Transparent, darkIcons = MaterialTheme.colors.isLight ) Surface(color = MaterialTheme.colors.background) { Scaffold( modifier = Modifier.fillMaxSize() ) { Column { // 填充留白状态栏高度 Spacer(modifier = Modifier .statusBarsHeight() .fillMaxWidth() ) // 你的业务 Composable } } } } } }- 效果
修改前 FitsSystemWindows :false 修改颜色 适配高度 
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- 状态栏透明
下拉刷新
构建错误：是com.google.accompanist:accompanist:xxx 相关库的版本不兼容，需要依赖相同的版本
21:35:51.503 7789-7789/com.jesen.driverexampaging E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.jesen.driverexampaging, PID: 7789
java.lang.NoSuchMethodError: No interface method startReplaceableGroup(ILjava/lang/String;)V in class Landroidx/compose/runtime/Composer; or its super classes (declaration of 'androidx.compose.runtime.Composer' appears in /data/app/~~4FT0iYbXWuoHva-X3Y0lBg==/com.jesen.driverexampaging-4uB2hZ7cDclbzM5qgmkttA==/base.apk)
at com.google.accompanist.swiperefresh.SwipeRefreshKt.rememberSwipeRefreshState(Unknown Source:5)
at com.jesen.driverexampaging.common.SwipeRefreshListKt.SwipeRefreshList(SwipeRefreshList.kt:31)
at com.jesen.driverexampaging.ui.composeview.RefreshExamListScreenKt.RefreshExamListScreen(RefreshExamListScreen.kt:33)
at com.jesen.driverexampaging.Main2Activity$onCreate$1$1$1$1$1.invoke(Main2Activity.kt:54)
at com.jesen.driverexampaging.Main2Activity$onCreate$1$1$1$1$1.invoke(Main2Activity.kt:47)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:116)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1$bodyContentPlaceables$1.invoke(Scaffold.kt:316)
at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1$bodyContentPlaceables$1.invoke(Scaffold.kt:314)
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效果 ：
<img src="./capture/11-20_225027.gif" alt="下拉刷新效果" style="zoom:50%;" /> -
基本用法：
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接入依赖：
// 下拉刷新 implementation "com.google.accompanist:accompanist-swiperefresh:0.21.2-beta" -
设置下拉刷新加载更多并判断状态
@Composable fun refreshLoadUse(viewModel: ExamViewModel) { // Swipe 的状态 val refreshState = rememberSwipeRefreshState(isRefreshing = false) val collectAsLazyPagingItems = viewModel.examList.collectAsLazyPagingItems() SwipeRefresh(state = refreshState, onRefresh = { collectAsLazyPagingItems.refresh() }) { LazyColumn( modifier = Modifier .fillMaxWidth() .fillMaxHeight(), content = { itemsIndexed(collectAsLazyPagingItems) { _, refreshData ->//每个item的展示 Box( modifier = Modifier .padding(horizontal = 14.dp, vertical = 4.dp) .fillMaxWidth() .height(50.dp) .background(Color.Green, shape = RoundedCornerShape(8.dp)) .border( width = 1.dp, color = Color.Red, shape = RoundedCornerShape(8.dp) ) .padding(start = 10.dp), contentAlignment = Alignment.CenterStart ) { Text(text = refreshData?.data ?: "") } } // append 标识非第一页，也就是指下一页或加载更多 when (collectAsLazyPagingItems.loadState.append) { is LoadState.Loading -> { //加载中的尾部item展示 item { Box( modifier = Modifier .fillMaxWidth() .height(50.dp), contentAlignment = Alignment.Center ) { Text(text = "加载中。。。") } } } is LoadState.Error -> { //更多，加载错误展示的尾部item item { Box( modifier = Modifier .fillMaxWidth() .height(50.dp), contentAlignment = Alignment.Center ) { Text(text = "--加载错误--") } } } } } ) } }
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简单封装
参数1：LazyPagingItems包装的请求结果，可以存储在ViewModel,从ViewMode获取
参数2：列表内容 listContent 需要外部传入需要携带上下文LazyListScope，可复用/** * 下拉加载封装 * * implementation "com.google.accompanist:accompanist-swiperefresh:xxx" * */ @Composable fun <T : Any> SwipeRefreshList( collectAsLazyPagingItems: LazyPagingItems<T>, listContent: LazyListScope.() -> Unit, ) { val rememberSwipeRefreshState = rememberSwipeRefreshState(isRefreshing = false) SwipeRefresh( state = rememberSwipeRefreshState, onRefresh = { collectAsLazyPagingItems.refresh() } ) { rememberSwipeRefreshState.isRefreshing = collectAsLazyPagingItems.loadState.refresh is LoadState.Loading LazyColumn( modifier = Modifier .fillMaxWidth() .fillMaxHeight(), ) { listContent() collectAsLazyPagingItems.apply { when { loadState.append is LoadState.Loading -> { //加载更多，底部loading item { LoadingItem() } } loadState.append is LoadState.Error -> { //加载更多异常 item { ErrorMoreRetryItem() { collectAsLazyPagingItems.retry() } } } loadState.refresh is LoadState.Error -> { if (collectAsLazyPagingItems.itemCount <= 0) { //刷新的时候，如果itemCount小于0，第一次加载异常 item { ErrorContent() { collectAsLazyPagingItems.retry() } } } else { item { ErrorMoreRetryItem() { collectAsLazyPagingItems.retry() } } } } loadState.refresh is LoadState.Loading -> { // 第一次加载且正在加载中 if (collectAsLazyPagingItems.itemCount == 0) { } } } } } } } /** * 底部加载更多失败处理 * */ @Composable fun ErrorMoreRetryItem(retry: () -> Unit) { Box(modifier = Modifier.fillMaxWidth(), contentAlignment = Alignment.Center) { TextButton( onClick = { retry() }, modifier = Modifier .padding(20.dp) .width(80.dp) .height(30.dp), shape = RoundedCornerShape(6.dp), contentPadding = PaddingValues(3.dp), colors = textButtonColors(backgroundColor = gray300), elevation = elevation( defaultElevation = 2.dp, pressedElevation = 4.dp, ), ) { Text(text = "请重试", color = gray600) } } } /** * 页面加载失败处理 * */ @Composable fun ErrorContent(retry: () -> Unit) { Column( modifier = Modifier .fillMaxSize() .padding(top = 100.dp), verticalArrangement = Arrangement.Center, horizontalAlignment = Alignment.CenterHorizontally ) { Image( modifier = Modifier.padding(top = 80.dp), painter = painterResource(id = R.drawable.ic_default_empty), contentDescription = null ) Text(text = "请求失败，请检查网络", modifier = Modifier.padding(8.dp)) TextButton( onClick = { retry() }, modifier = Modifier .padding(20.dp) .width(80.dp) .height(30.dp), shape = RoundedCornerShape(10.dp), contentPadding = PaddingValues(5.dp), colors = textButtonColors(backgroundColor = gray300), elevation = elevation( defaultElevation = 2.dp, pressedElevation = 4.dp, ) //colors = ButtonDefaults ) { Text(text = "重试", color = gray700) } } } /** * 底部加载更多正在加载中... * */ @Composable fun LoadingItem() { Row( modifier = Modifier .height(34.dp) .fillMaxWidth() .padding(5.dp), horizontalArrangement = Arrangement.Center ) { CircularProgressIndicator( modifier = Modifier .size(24.dp), color = gray600, strokeWidth = 2.dp ) Text( text = "加载中...", color = gray600, modifier = Modifier .fillMaxHeight() .padding(start = 20.dp), fontSize = 18.sp, ) } }-
用法：
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列表布局：
/** * 首页列表加载 ---下拉刷新，加载更多动效 * */ @Composable fun RefreshExamListScreen( viewModel: ExamViewModel, context: Context, ) { val collectAsLazyPagingIDataList = viewModel.examList.collectAsLazyPagingItems() SwipeRefreshList( collectAsLazyPagingItems = collectAsLazyPagingIDataList ) { itemsIndexed(collectAsLazyPagingIDataList) { index, data -> // 列表Item QItemView( index = index, que = data, onClick = { Toast.makeText(context, "ccc", Toast.LENGTH_SHORT).show() }, ) } } } -
ViewModel,包括Paging3的配置:
class ExamViewModel : ViewModel() { val examList = Pager( config = PagingConfig( pageSize = 4, // 每一页个数 initialLoadSize = 8, // 第一次加载数量，如果不设置的话是 pageSize * 2 prefetchDistance = 2, // 距离下一页请求的距离 ) ) { // 此类处理了分页功能 ExamSource(Repository) }.flow.cachedIn(viewModelScope) } -
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代码：【驾校考题列表】 https://github.com/Jesen0823/UseCompose/tree/main/DriverExamPaging
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