開始整合 Navigation,實現單 Activity + Compose 模式的開發。

封裝 Navigation 通用類和拓展方法

新建模組 lib_compose 新增 navigation 包開始封裝 Navigation 的通用類。

Screen.kt

將 NavGraphBuilder.composable() DSL 中的引數收攏到 Screen 。

route 屬性根據 arguments 生成避免手打 String 時容易產生錯誤。
createRoute() 方法根據提供的引數名/引數值生成 NavController.navigate() 方法使用的 route 引數

``` abstract class Screen(private val path:String){ //根路由，相當於分組標籤 abstract val root:String

open val arguments:List = emptyList() open val deepLinks:List = emptyList() //必填引數名 private val requiredArgs:MutableList = mutableListOf() //可選引數名+預設值 map private val optionalArgs:MutableMap = mutableMapOf()

private val routePath by lazy { if (root.isEmpty()) path else "$root/${path}" }

/* * 自動生成的 route ，配置 DSL 時使用 * route = rootRoute/path/必填引數?可選引數 / val route:String by lazy { val sb = StringBuilder(routePath) //解析引數時將必選/可選引數分別儲存起來 for (arg in arguments){ if (arg.argument.isNullable || arg.argument.isDefaultValuePresent){ //可選引數 sb.append("?${arg.name}={${arg.name}}") optionalArgs[arg.name] = arg.argument.defaultValue }else{ sb.append("/{${arg.name}}") requiredArgs.add(arg.name) } } sb.toString() }

/* * 通用方法 * 根據傳入的 map 生成 navigate 方法所需 route * map 中必須包括所有的必填引數 * @param args Map key:引數名,value:引數值 * @return String 呼叫 navigate 方法所需 route / fun createRoute(args:Map = emptyMap()):String{ val sb = StringBuilder(routePath) if (args.isEmpty() && requiredArgs.isNotEmpty()){ throw IllegalArgumentException("param [args:Map] can't be empty") }else{ for (requiredArg in requiredArgs){ if (!args.containsKey(requiredArg)){ throw IllegalArgumentException("required argument $requiredArg can't find in param [args:Map]") } sb.append("/${args[requiredArg]}") } for (optionalArg in optionalArgs){ if (args.containsKey(optionalArg.key)){ //引數中有可選引數 sb.append("?${optionalArg.key}={${args[optionalArg.key]}}") }else if (optionalArg.value != null){ // 可選引數有預設值 sb.append("?${optionalArg.key}={${optionalArg.value}}") } } } return sb.toString() }

} ```

NavGraphKtx.kt

包裝 NavGraphBuilder.composable(),提供可以直接使用 Screen 配置的拓展。 fun NavGraphBuilder.composableScreen( screen: Screen, content: @Composable (NavBackStackEntry) -> Unit ) { composable( route = screen.route, arguments = screen.arguments, deepLinks = screen.deepLinks, content = content ) } 封裝 Screen 分組配置 NavGraph

重寫 composeScreens 配置頁面路由
create() 方法生成 NavGraph ``` abstract class ScreenNavGraph(protected val navController: NavController,private val startScreen:Screen){

protected abstract val composeScreens: NavGraphBuilder.() -> Unit

fun create(builder: NavGraphBuilder){ builder.run { navigation(startDestination = startScreen.route,route = startScreen.root){ composeScreens.invoke(this) } } } } ```

實現首頁路由

ui 模組的路由配置

ui 模組新增 lib_compose 依賴，在每個模組中新建 route 包，新增 Screens.kt ，以 ui-home 為例 ``` sealed class HomeScreens(path:String):Screen(path) { override val root: String get() = "home"

object Index:HomeScreens("index") //abstract 是為涉及跨模組路由時定義抽象方法或屬性 abstract class NavGraph(navController: NavController):ScreenNavGraph(navController,Index){

override val composeScreens: NavGraphBuilder.() -> Unit = { composableScreen(Index){ UiHome() } } } } ```

建立 WanNavHost()

將所有路由配置到 WanNavHost() 中 ``` @Composable fun WanNavHost(modifier: Modifier = Modifier,navController: NavHostController){

NavHost(modifier= modifier,navController = navController, startDestination = HomeScreens.Index.root){
    HomeGraph(navController).create(this)
    FaqGraph(navController).create(this)
    ProjectGraph(navController).create(this)
    SquareGraph(navController).create(this)
    SystemGraph(navController).create(this)
    ProfileGraph(navController).create(this)
}

}

private class HomeGraph(navController: NavHostController) : HomeScreens.NavGraph(navController)

private class ProfileGraph(navController: NavHostController) : ProfileScreens.NavGraph(navController)

private class FaqGraph(navController: NavHostController) : FqaScreens.NavGraph(navController)

private class ProjectGraph(navController: NavHostController) : ProjectScreens.NavGraph(navController)

private class SquareGraph(navController: NavHostController) : SquareScreens.NavGraph(navController)

private class SystemGraph(navController: NavHostController) : SystemScreens.NavGraph(navController) ```

修改 WanApp()

``` @OptIn(ExperimentalMaterial3Api::class) @Composable fun WanApp(){ //建立 navController val navController = rememberNavController() var selectedItemIndex by remember { mutableStateOf(0) } val bottomBarItems = remember { BottomBarItem.values() }

WanAndroidTheme { // A surface container using the 'background' color from the theme Surface( modifier = Modifier.fillMaxSize(), color = MaterialTheme.colorScheme.background ) { Scaffold( topBar = { TopBar(title = bottomBarItems[selectedItemIndex].label) {} }, bottomBar = { BottomBar(bottomBarItems, selectedItemIndex) { // 修改 BottomBarItem 點選事件 if (it != selectedItemIndex) { selectedItemIndex = it navController.navigate(bottomBarItems[selectedItemIndex].route) { popUpTo(navController.graph.findStartDestination().id) { saveState = true } launchSingleTop = true restoreState = true } } } }, containerColor = Color.LightGray ) { //替換成 WanNavHost WanNavHost(modifier = Modifier.padding(it),navController = navController) } } } } ```