顶部应用栏和底部应用栏的两个不同菜单，带有导航组件

我正在尝试使用Android Navigation Architecture Component，并且正在调查Material design指南 . 我真的受到了design的启发：

对于顶部工具栏，我可以通过 setSupportActionBar(toolbar) 然后在 MainActivity 中设置它：

public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu, menu);
    return super.onCreateOptionsMenu(menu);
}

但是在尝试时我无法弄清楚如何在顶部和底部应用栏上为不同的片段实现菜单，特别是对于底部应用栏 .

For example ，我想在 DetailFragment 上显示 a favorite icon on bottom app bar only ，但在 MainActivity 上，它应该消失了 .

我目前的代码：

MainActivity

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        NavController navController = Navigation.findNavController(this, R.id.nav_host);
        NavigationUI.setupActionBarWithNavController(this, navController);


        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(view -> Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                .setAction("Action", null).show());


    }

    @Override
    public boolean onSupportNavigateUp() {
        return Navigation.findNavController(this, R.id.nav_host).navigateUp();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu, menu);
        return super.onCreateOptionsMenu(menu);
    }
}

MainFragment

public class MainFragment extends Fragment {

    public MainFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_main, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        Button buttonOne = view.findViewById(R.id.button_one);
        buttonOne.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.detailFragment));
    }

}

DetailFragment

public class DetailFragment extends Fragment {

    public DetailFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_detail, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:animateLayoutChanges="true"
    tools:context=".MainActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:animateLayoutChanges="true"
        android:theme="@style/AppTheme.AppBarOverlay">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </com.google.android.material.appbar.AppBarLayout>

    <fragment
        android:id="@+id/nav_host"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="top"
        android:layout_marginTop="?android:attr/actionBarSize"
        app:defaultNavHost="true"
        app:layout_anchor="@id/bottom_appbar"
        app:layout_anchorGravity="top"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:navGraph="@navigation/mobile_navigation" />

    <com.google.android.material.bottomappbar.BottomAppBar
        android:id="@+id/bottom_appbar"
        android:layout_width="match_parent"
        android:layout_height="?android:attr/actionBarSize"
        android:layout_gravity="bottom" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/bottom_appbar" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

mobile_navigation.xml

<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/mainFragment">
    <fragment
        android:id="@+id/mainFragment"
        android:name="com.example.MainFragment"
        android:label="fragment_main"
        tools:layout="@layout/fragment_main" >
        <action
            android:id="@+id/toAccountFragment"
            app:destination="@id/detailFragment" />
    </fragment>
    <fragment
        android:id="@+id/detailFragment"
        android:name="com.example.DetailFragment"
        android:label="fragment_account"
        tools:layout="@layout/fragment_detail" />
</navigation>

menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/app_bar_settings"
        android:title="@string/action_settings"
        app:showAsAction="never" />
</menu>

bottom_appbar_menu.xml 仅适用于 DetialFragment

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_bottom_fav"
        android:icon="@drawable/ic_favorite"
        android:title="@string/action_favorite"
        app:showAsAction="ifRoom" />
</menu>

任何帮助表示赞赏 .

My Findings:

这是我能够想到的，但不满意，因为我不知道这是否是写它的方式 . 我发布了一个可能的解决方案：

1- MainActivity

NavController navController = Navigation.findNavController(this, R.id.nav_host);
NavigationUI.setupWithNavController(toolbar, navController);

2-为底部应用栏创建两个不同的菜单（我没有尝试动态添加菜单项），例如，一个带有空白菜单xml，另一个带有收藏夹图标 .

为简单起见，请覆盖 MainActivity 中的 onCreateOptionsMenu ：

public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu, menu);
    bottomAppBar.replaceMenu(R.menu.bottom_menu_blank);
    return super.onCreateOptionsMenu(menu);
}

感谢@ʍѳђઽ૯ท让我知道Bottom App Bar的 replaceMenu 方法 .

3-然后再次在 DetailFragment 中使用 setHasOptionsMenu(true) 并覆盖 onCreateOptionsMenu ：

public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    super.onCreateOptionsMenu(menu, inflater);
    BottomAppBar bottomAppBar = getActivity().findViewById(R.id.bottom_appbar);
    bottomAppBar.replaceMenu(R.menu.bottom_menu_fav);
}

如果有人有更好的方法，请告诉我们 .