从其他页面返回Composable时，如何重新触发focusRequester.requestFocus()？

原代码中LaunchedEffect(Unit)仅在Composable首次初始化时执行一次。当你从浏览器返回当前页面时，该Composable并未被销毁重建，因此这个副作用不会再次触发，导致focusRequester.requestFocus()不执行，键盘也就不会自动弹出。

方案一：监听页面生命周期，在恢复时请求焦点 #

利用repeatOnLifecycle监听页面的RESUMED状态，每次页面从后台回到前台（比如从浏览器返回）时，都会触发焦点请求和键盘弹出逻辑：

@Composable
fun MyBasicTextField() {
    val keyboardController = LocalSoftwareKeyboardController.current
    val focusRequester = remember { FocusRequester() }
    val lifecycleOwner = LocalLifecycleOwner.current

    BasicTextField(
        modifier = Modifier.focusRequester(focusRequester),
        keyboardActions = KeyboardActions(onAny = { keyboardController?.hide() }),
        // 补充BasicTextField必需的value和onValueChange参数
        value = "",
        onValueChange = {}
    )

    LaunchedEffect(lifecycleOwner) {
        lifecycleOwner.repeatOnLifecycle(Lifecycle.State.RESUMED) {
            focusRequester.requestFocus()
            // 手动调用show确保键盘弹出（部分场景下请求焦点后键盘不会自动弹出）
            keyboardController?.show()
        }
    }
}

方案二：结合导航组件监听当前页面状态（使用Jetpack Navigation时） #

如果你的页面是通过Jetpack Navigation管理的，可以监听当前返回栈条目，判断页面是否处于活跃状态，再触发焦点请求：

@Composable
fun MyBasicTextField(navController: NavController) {
    val keyboardController = LocalSoftwareKeyboardController.current
    val focusRequester = remember { FocusRequester() }
    val currentBackStackEntry by navController.currentBackStackEntryAsState()
    // 替换为你的页面路由
    val isCurrentScreen = currentBackStackEntry?.destination?.route == "text_field_screen"

    BasicTextField(
        modifier = Modifier.focusRequester(focusRequester),
        keyboardActions = KeyboardActions(onAny = { keyboardController?.hide() }),
        value = "",
        onValueChange = {}
    )

    LaunchedEffect(isCurrentScreen) {
        if (isCurrentScreen) {
            focusRequester.requestFocus()
            keyboardController?.show()
        }
    }
}

内容的提问来源于stack exchange，提问作者Edna Krabappel