Compose 实现下拉刷新和上拉加载，详尽方法论解析

2024-01-30 06:22:51

前言

Compose 作为 Android 开发的新利器，以其简洁的语法和强大的灵活性征服了众多开发者，然而 Compose 缺少原生支持下拉刷新和上拉加载，这对于习惯于下拉刷新和上拉加载的用户来说，无疑是一种遗憾。

下拉刷新

方案一：SwipeRefreshLayout

Compose 中的 SwipeRefreshLayout 是一个可以检测用户下拉手势的组件，通常与列表结合使用，实现下拉刷新。

首先，我们需要在布局文件中添加 SwipeRefreshLayout 组件，并将其作为列表的父布局。

@Composable
fun RefreshList() {
    val scaffoldState = rememberScaffoldState()
    Scaffold(
        scaffoldState = scaffoldState,
        topBar = { TopAppBar(title = { Text("下拉刷新") }) },
        content = { RefreshContent(scaffoldState) }
    )
}

@Composable
fun RefreshContent(scaffoldState: ScaffoldState) {
    val items = listOf("A", "B", "C", "D", "E")
    SwipeRefreshLayout(
        state = rememberSwipeRefreshState(isRefreshing = false),
        onRefresh = {
            // 刷新操作
        }
    ) {
        List(items) { Text(text = "$it") }
    }
}

方案二：自定义

除了 SwipeRefreshLayout，我们还可以自定义实现下拉刷新。一种常见的方法是使用 gesture-detector 组件，该组件可以检测用户的触摸手势。

@Composable
fun CustomRefreshList() {
    val scaffoldState = rememberScaffoldState()
    Scaffold(
        scaffoldState = scaffoldState,
        topBar = { TopAppBar(title = { Text("自定义下拉刷新") }) },
        content = { CustomRefreshContent(scaffoldState) }
    )
}

@Composable
fun CustomRefreshContent(scaffoldState: ScaffoldState) {
    val items = listOf("A", "B", "C", "D", "E")
    val gestureDetectorState = rememberGestureDetectorState()
    Box(modifier = Modifier.gestureDetector(gestureDetectorState, emptyList())) {
        List(items) { Text(text = "$it") }
    }
}

上拉加载

方案一：自定义

与下拉刷新类似，上拉加载也可以使用 gesture-detector 组件实现。

@Composable
fun LoadMoreList() {
    val scaffoldState = rememberScaffoldState()
    Scaffold(
        scaffoldState = scaffoldState,
        topBar = { TopAppBar(title = { Text("上拉加载") }) },
        content = { LoadMoreContent(scaffoldState) }
    )
}

@Composable
fun LoadMoreContent(scaffoldState: ScaffoldState) {
    val items = listOf("A", "B", "C", "D", "E")
    val gestureDetectorState = rememberGestureDetectorState()
    Box(modifier = Modifier.gestureDetector(gestureDetectorState, emptyList())) {
        Column {
            List(items) { Text(text = "$it") }
            Text(text = "上拉加载更多")
        }
    }
}