android studio 用代码写出图书管理界面，该界面中底部有4个导航栏，分别是首页、场馆、书架和我 的，分别对应4个不同的Fragment的布局样式

好的，让我们来写一个简单的图书管理界面，代码如下：

1. MainActivity.java

public class MainActivity extends AppCompatActivity {

    private BottomNavigationView bottomNavigationView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bottomNavigationView = findViewById(R.id.bottom_navigation);

        // 设置默认选中的导航栏
        bottomNavigationView.setSelectedItemId(R.id.navigation_home);

        // 监听导航栏的切换事件
        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                Fragment fragment = null;

                switch (item.getItemId()) {
                    case R.id.navigation_home:
                        fragment = new HomeFragment();
                        break;
                    case R.id.navigation_venue:
                        fragment = new VenueFragment();
                        break;
                    case R.id.navigation_bookshelf:
                        fragment = new BookshelfFragment();
                        break;
                    case R.id.navigation_me:
                        fragment = new MeFragment();
                        break;
                }

                // 替换当前的Fragment
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragment).commit();

                return true;
            }
        });
    }
}

2. 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/layout_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@id/bottom_navigation"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="@color/white"
        app:itemIconTint="@drawable/bottom_navigation_item_color"
        app:itemTextColor="@drawable/bottom_navigation_item_color"
        app:labelVisibilityMode="labeled"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_navigation_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

3. bottom_navigation_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/navigation_home"
        android:icon="@drawable/ic_home"
        android:title="@string/navigation_home" />
    <item
        android:id="@+id/navigation_venue"
        android:icon="@drawable/ic_venue"
        android:title="@string/navigation_venue" />
    <item
        android:id="@+id/navigation_bookshelf"
        android:icon="@drawable/ic_bookshelf"
        android:title="@string/navigation_bookshelf" />
    <item
        android:id="@+id/navigation_me"
        android:icon="@drawable/ic_me"
        android:title="@string/navigation_me" />
</menu>

4. HomeFragment.java

public class HomeFragment extends Fragment {

    public HomeFragment() {
        // 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_home, container, false);
    }
}

5. fragment_home.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="Home Fragment"
        android:textSize="30sp"
        android:layout_gravity="center"/>

</LinearLayout>

6. VenueFragment.java

public class VenueFragment extends Fragment {

    public VenueFragment() {
        // 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_venue, container, false);
    }
}

7. fragment_venue.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="Venue Fragment"
        android:textSize="30sp"
        android:layout_gravity="center"/>

</LinearLayout>

8. BookshelfFragment.java

public class BookshelfFragment extends Fragment {

    public BookshelfFragment() {
        // 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_bookshelf, container, false);
    }
}

9. fragment_bookshelf.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="Bookshelf Fragment"
        android:textSize="30sp"
        android:layout_gravity="center"/>

</LinearLayout>

10. MeFragment.java

public class MeFragment extends Fragment {

    public MeFragment() {
        // 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_me, container, false);
    }
}

11. fragment_me.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="Me Fragment"
        android:textSize="30sp"
        android:layout_gravity="center"/>

</LinearLayout>

以上就是一个简单的图书管理界面，包含4个不同的Fragment的布局样式和底部的导航栏。