自定义 BottomNavigationView 的行为-解网

问：

我想在单击其中的不同选项卡时弹出一个片段。BottomNavigationView

我有三个选项卡，其中第二个作为起始目的地。在第二个选项卡上，我可以搜索一些项目，后端的数据将显示在此堆栈中的另一个片段上，换句话说：BottomNavigationView

A - B - C (origin state)

    D
A - B - C (state after search has been performed)

在返回按钮单击时，此片段将被删除到原始状态，但如果在搜索用户单击另一个选项卡 A 或 C 后，堆栈将保留 D 片段，而 D 片段将在用户返回 B 选项卡后显示。 A - B - C

导航支持 in xml 选项，但默认导航不会在 xml 中定义导航操作 - 它支持开箱即用。至少我还没有找到如何覆盖这种行为。我可能会听导航更改，但不清楚接下来如何进行。其他一些使用 fragmentManager.replace（）的解决方案看起来很丑陋。看起来更好，但我还没有设法将其正确应用于这种情况，这也引起了对处理导航组件的正确方法的担忧。popUpInclusiveBottomNavigationViewOnItemViewSelectedListenernavigateUp()

实现这种行为的正确方法是什么？我希望当用户导航到其他选项卡时，从堆栈中弹出我的搜索片段。

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/mobile_navigation"
    app:startDestination="@+id/navigation_dashboard">

    <fragment
        android:id="@+id/navigation_home"
        android:name="ru.home.government.screens.deputies.DeputiesFragment"
        android:label="@string/title_deputies"
        tools:layout="@layout/fragment_deputies">
        <argument
            android:name="EXTRA_NO_BOTTOM_VIEW"
            app:argType="boolean"
            android:defaultValue="false" />

        <action
            android:id="@+id/action_navigation_home_to_navigation_dashboard"
            app:destination="@id/navigation_dashboard"
            app:popUpTo="@+id/navigation_home"
            app:popUpToInclusive="true" />

    </fragment>

    <fragment
        android:id="@+id/navigation_dashboard"
        android:name="ru.home.government.screens.laws.main.LawsMainFragment"
        android:label="@string/title_laws"
        tools:layout="@layout/fragment_laws" >

        <action
            android:id="@+id/action_navigation_dashboard_to_lawsFilteredFragment"
            app:destination="@id/navigation_laws_filtered"
            />
        <action
            android:id="@+id/action_navigation_dashboard_to_navigation_home"
            app:destination="@id/navigation_home"
            app:popUpTo="@+id/navigation_dashboard"
            app:popUpToInclusive="true"
            />
        <action
            android:id="@+id/action_navigation_dashboard_to_navigation_notifications"
            app:destination="@id/navigation_notifications"
            app:popUpTo="@+id/navigation_dashboard"
            app:popUpToInclusive="true"
            />

    </fragment>

    <fragment
        android:id="@+id/navigation_notifications"
        android:name="ru.home.government.screens.tracker.TrackerFragment"
        android:label="@string/title_tracker"
        tools:layout="@layout/fragment_tracker">

        <action
            android:id="@+id/action_navigation_notifications_to_navigation_dashboard"
            app:destination="@id/navigation_dashboard"
            app:popUpTo="@+id/navigation_home"
            app:popUpToInclusive="true" />

    </fragment>

    <fragment
        android:id="@+id/navigation_laws_filtered"
        android:name="ru.home.government.screens.laws.filter.LawsFilteredFragment"
        android:label="@string/title_search"
        tools:layout="@layout/fragment_law_filtered">

        <argument
            android:name="EXTRA_KEY"
            app:argType="string"
            android:defaultValue="false" />

        <action
            android:id="@+id/action_navigation_laws_filtered_to_navigation_home"
            app:destination="@id/navigation_home"
            app:popUpTo="@+id/navigation_dashboard"
            app:popUpToInclusive="true" />

        <action
            android:id="@+id/action_navigation_laws_filtered_to_navigation_notifications"
            app:destination="@id/navigation_notifications"
            app:popUpTo="@+id/navigation_dashboard"
            app:popUpToInclusive="true" />

    </fragment>
</navigation>

Android 导航 BottomNavigationView

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/mobile_navigation"
    app:startDestination="@+id/navigation_dashboard">

    <fragment
        android:id="@+id/navigation_home"
        android:name="ru.home.government.screens.deputies.DeputiesFragment"
        android:label="@string/title_deputies"
        tools:layout="@layout/fragment_deputies">
        <argument
            android:name="EXTRA_NO_BOTTOM_VIEW"
            app:argType="boolean"
            android:defaultValue="false" />

        <action
            android:id="@+id/action_navigation_home_to_navigation_dashboard"
            app:destination="@id/navigation_dashboard" />

    </fragment>

    <fragment
        android:id="@+id/navigation_dashboard"
        android:name="ru.home.government.screens.laws.main.LawsMainFragment"
        android:label="@string/title_laws"
        tools:layout="@layout/fragment_laws" >

        <action
            android:id="@+id/action_navigation_dashboard_to_lawsFilteredFragment"
            app:destination="@id/navigation_laws_filtered"
            />
        <action
            android:id="@+id/action_navigation_dashboard_to_navigation_home"
            app:destination="@id/navigation_home" />
        <action
            android:id="@+id/action_navigation_dashboard_to_navigation_notifications"
            app:destination="@id/navigation_notifications"
            app:popUpTo="@+id/navigation_dashboard"
            app:popUpToInclusive="true"
            />

    </fragment>

    <fragment
        android:id="@+id/navigation_notifications"
        android:name="ru.home.government.screens.tracker.TrackerFragment"
        android:label="@string/title_tracker"
        tools:layout="@layout/fragment_tracker">

        <action
            android:id="@+id/action_navigation_notifications_to_navigation_dashboard"
            app:destination="@id/navigation_dashboard"
            app:popUpTo="@+id/navigation_home"
            app:popUpToInclusive="true" />

    </fragment>

    <fragment
        android:id="@+id/navigation_laws_filtered"
        android:name="ru.home.government.screens.laws.filter.LawsFilteredFragment"
        android:label="@string/title_search"
        tools:layout="@layout/fragment_law_filtered">

        <argument
            android:name="EXTRA_KEY"
            app:argType="string"
            android:defaultValue="false" />

        <action
            android:id="@+id/action_navigation_laws_filtered_to_navigation_home"
            app:destination="@id/navigation_home" />

        <action
            android:id="@+id/action_navigation_laws_filtered_to_navigation_notifications"
            app:destination="@id/navigation_notifications" />

    </fragment>
</navigation>

注意*** 如果您想在后按时从通知导航到主页，请不要执行最后一部分，否则请执行以下步骤

和背压处理

定义 backPressedCallback

private val backPressedCallback = object : OnBackPressedCallback(enabled = true) {
    override fun handleOnBackPressed() {
        if (navController.currentDestination?.id == R.id.navigation_notifications) {
            navController.navigate(R.id.action_navigation_notifications_to_navigation_dashboard)
        }
    }
}

注册它

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

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

    navView.setupWithNavController(navController)
    navController.addOnDestinationChangedListener { _, destination, _ ->
        backPressedCallback.isEnabled = destination.id == R.id.navigation_notifications // enable back press custom handling only when notifications screen is on 
    }
    onBackPressedDispatcher.addCallback(this, backPressedCallback)
}

自定义 BottomNavigationView 的行为

Customize behavior of BottomNavigationView

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