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我确实查看了官方网站Nested Graph并搜索了相关问题，但没有运气。

当嵌套图和动态特征模块出现时，我尝试将“动态特征模块”、“嵌套 NavHostFragments”和“嵌套图”组合成一个单独的模块。但是当我尝试处理后退按钮事件时，我对此一无所知。

我在“应用程序”模块中有 NavHostFragments，当用户在底部导航视图中导航帐户项目时。它将提示一个底部对话框，其中包含一个嵌套的 NavHostFragment 及其导航图。这些片段位于“帐户”模块中。

当我尝试通过按帐户页面中的后退按钮进行导航时，它不会返回嵌套的 NavHostFragment 内的堆栈。这个setPrimaryNavigationFragment()函数似乎为这个问题提供了一些线索，但我没有运气。

这就是现在的行为

当前行为

MainActivity.kt（在“app”模块中）

class MainActivity : AppCompatActivity() {
    private lateinit var toolbar: Toolbar
    private lateinit var appBarConfiguration: AppBarConfiguration
    private val navController: NavController by lazy {
        findNavController(R.id.nav_host_fragment)
    }
    private val listener =
        NavController.OnDestinationChangedListener { controller, destination, arguments ->
            model.triggerDestination(destinationId = destination.id)
        }

    private val model: MainActivityViewModel by viewModels()


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        toolbar = findViewById(R.id.toolbar)
        setSupportActionBar(toolbar)

        val navView: BottomNavigationView = findViewById(R.id.nav_view)

        appBarConfiguration = AppBarConfiguration(
            setOf(
                R.id.navigation_explore
            )
        )

        setupActionBarWithNavController(navController, appBarConfiguration)
        navView.setupWithNavController(navController)

        model.notificationPageSelect.observe(this, EventObserver {
            when (it) {
                R.id.navigation_explore -> updateAppBarBg(R.drawable.explore_appbar_bg_gradient)
                R.id.navigation_notifications -> updateAppBarBg(R.drawable.notification_appbar_bg_gradient)
            }
        })
    }

    private fun updateAppBarBg(appBg: Int) {
        toolbar.setBackgroundResource(appBg)
    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.overflow_menu, menu)
        return super.onCreateOptionsMenu(menu)
    }

    override fun onSupportNavigateUp(): Boolean {
        return navController.navigateUp(appBarConfiguration)
    }

    override fun onResume() {
        super.onResume()
        navController.addOnDestinationChangedListener(listener)
    }

    override fun onPause() {
        super.onPause()
        navController.removeOnDestinationChangedListener(listener)
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="0dp"
        android:layout_height="50dp"
        android:background="@drawable/explore_appbar_bg_gradient"
        android:theme="@style/ThemeOverlay.MaterialComponents.Dark.ActionBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.coordinatorlayout.widget.CoordinatorLayout
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/toolbar">
        <fragment
            android:id="@+id/nav_host_fragment"
            android:name="androidx.navigation.dynamicfeatures.fragment.DynamicNavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="true"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/toolbar"
            app:navGraph="@navigation/mobile_navigation" />

        <com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/nav_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="0dp"
            android:layout_marginEnd="0dp"
            android:background="?android:attr/windowBackground"
            app:labelVisibilityMode="labeled"
            app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
            app:menu="@menu/bottom_nav_menu"
            app:layout_anchorGravity="bottom|right|end"
            android:layout_gravity="bottom|end"
            />
    </androidx.coordinatorlayout.widget.CoordinatorLayout>



</androidx.constraintlayout.widget.ConstraintLayout>

AccountListDialogFragment.kt（在“帐户”模块中）

class AccountListDialogFragment : BottomSheetDialogFragment() {

    private lateinit var viewModel: SettingsViewModel

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.fragment_account, container, false)

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProvider(this).get(SettingsViewModel::class.java)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        setupFullExpand()
    }

}

片段帐户.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/account" />


</androidx.constraintlayout.widget.ConstraintLayout>
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