activity_main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:design="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.segunfamisa.sample.bottomnav.MainActivity">

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="#f1f1f1">

    </FrameLayout>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="start"
        design:menu="@menu/bottom_nav_items" />
</LinearLayout>

fragment_menu.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragment_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.segunfamisa.sample.bottomnav.MenuFragment">

    <TextView
        android:id="@+id/text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textColor="@android:color/white"
        android:gravity="center"
        />

</RelativeLayout>

在菜单文件夹中创建此文件,

bottom_nav_items.xml：

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

    <item
        android:id="@+id/action_home"
        android:enabled="true"
        android:icon="@android:drawable/ic_dialog_map"
        android:title="One"
        app:showAsAction="ifRoom"/>
    <item
        android:id="@+id/action_category"
        android:enabled="true"
        android:icon="@android:drawable/ic_dialog_info"
        android:title="Two"
        app:showAsAction="ifRoom"/>
    <item
        android:id="@+id/action_me"
        android:enabled="true"
        android:icon="@android:drawable/ic_dialog_email"
        android:title="Three"
        app:showAsAction="ifRoom"/>
    <item
        android:id="@+id/action_setting"
        android:enabled="true"
        android:icon="@android:drawable/ic_popup_reminder"
        android:title="Four"
        app:showAsAction="ifRoom"/>
</menu>

MainActivity.java：

public class MainActivity extends AppCompatActivity {
    private static final String SELECTED_ITEM = "arg_selected_item";

    private BottomNavigationView mBottomNav;
    private int mSelectedItem;

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

        mBottomNav = (BottomNavigationView) findViewById(R.id.navigation);

        disableShiftMode(mBottomNav);
        mBottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                selectFragment(item);
                return true;
            }
        });

        MenuItem selectedItem;
        if (savedInstanceState != null) {
            mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM,0);
            selectedItem = mBottomNav.getMenu().findItem(mSelectedItem);
        } else {
            selectedItem = mBottomNav.getMenu().getItem(0);
        }
        selectFragment(selectedItem);
    }

    public static void disableShiftMode(BottomNavigationView view) {
        BottomNavigationMenuView menuView = (BottomNavigationMenuView) view.getChildAt(0);
        try {
            Field shiftingMode = menuView.getClass().getDeclaredField("mShiftingMode");
            shiftingMode.setAccessible(true);
            shiftingMode.setBoolean(menuView,false);
            shiftingMode.setAccessible(false);
            for (int i = 0; i < menuView.getChildCount(); i++) {
                BottomNavigationItemView item = (BottomNavigationItemView) menuView.getChildAt(i);
                item.setShiftingMode(false);
                // set once again checked value,so view will be updated
                item.setChecked(item.getItemData().isChecked());
            }
        } catch (NoSuchFieldException e) {
            //Timber.e(e,"Unable to get shift mode field");
        } catch (IllegalAccessException e) {
            //Timber.e(e,"Unable to change value of shift mode");
        }
    }


    @Override
    protected void onSaveInstanceState(Bundle outState) {
        outState.putInt(SELECTED_ITEM,mSelectedItem);
        super.onSaveInstanceState(outState);
    }

    @Override
    public void onBackPressed() {
        MenuItem homeItem = mBottomNav.getMenu().getItem(0);
        if (mSelectedItem != homeItem.getItemId()) {
            // select home item
            selectFragment(homeItem);
        } else {
            super.onBackPressed();
        }
    }

    private void selectFragment(MenuItem item) {
        Fragment frag = null;
        // init corresponding fragment
        switch (item.getItemId()) {
            case R.id.action_home:
                frag = MenuFragment.newInstance(getString(R.string.text_home),getColorFromRes(R.color.color_home));
                break;
            case R.id.action_category:
                frag = MenuFragment.newInstance(getString(R.string.text_notifications),getColorFromRes(R.color.color_notifications));
                break;
            case R.id.action_me:
                frag = MenuFragment.newInstance(getString(R.string.text_search),getColorFromRes(R.color.color_search));
                break;
            case R.id.action_setting:
                frag = MenuFragment.newInstance(getString(R.string.text_home),getColorFromRes(R.color.color_home));
                break;
        }

        // update selected item
        mSelectedItem = item.getItemId();

        // uncheck the other items.
        for (int i = 0; i < mBottomNav.getMenu().size(); i++) {
            MenuItem menuItem = mBottomNav.getMenu().getItem(i);
            menuItem.setChecked(menuItem.getItemId() == item.getItemId());
        }

        updateToolbarText(item.getTitle());

        if (frag != null) {
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.add(R.id.container,frag,frag.getTag());
            ft.commit();
        }
    }

    private void updateToolbarText(CharSequence text) {
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setTitle(text);
        }
    }

    private int getColorFromRes(@ColorRes int resId) {
        return ContextCompat.getColor(this,resId);
    }

MenuFragment.java：

public class MenuFragment extends Fragment {
    private static final String ARG_TEXT = "arg_text";
    private static final String ARG_COLOR = "arg_color";

    private String mText;
    private int mColor;

    private View mContent;
    private TextView mTextView;

    public static Fragment newInstance(String text,int color) {
        Fragment frag = new MenuFragment();
        Bundle args = new Bundle();
        args.putString(ARG_TEXT,text);
        args.putInt(ARG_COLOR,color);
        frag.setArguments(args);
        return frag;
    }


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

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

        // retrieve text and color from bundle or savedInstanceState
        if (savedInstanceState == null) {
            Bundle args = getArguments();
            mText = args.getString(ARG_TEXT);
            mColor = args.getInt(ARG_COLOR);
        } else {
            mText = savedInstanceState.getString(ARG_TEXT);
            mColor = savedInstanceState.getInt(ARG_COLOR);
        }

        // initialize views
        mContent = view.findViewById(R.id.fragment_content);
        mTextView = (TextView) view.findViewById(R.id.text);

        // set text and background color
        mTextView.setText(mText);
        mContent.setBackgroundColor(mColor);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        outState.putString(ARG_TEXT,mText);
        outState.putInt(ARG_COLOR,mColor);
        super.onSaveInstanceState(outState);
    }
}

无论您需要做什么,只需禁用BottomNavigationView Shift模式,
在你的代码中使用此方法.

public static void disableShiftMode(BottomNavigationView view) {
        BottomNavigationMenuView menuView = (BottomNavigationMenuView) view.getChildAt(0);
        try {
            Field shiftingMode = menuView.getClass().getDeclaredField("mShiftingMode");
            shiftingMode.setAccessible(true);
            shiftingMode.setBoolean(menuView,"Unable to change value of shift mode");
        }
    }

像这样调用这个方法,

mBottomNav = (BottomNavigationView) findViewById(R.id.navigation);

        disableShiftMode(mBottomNav);

它会工作.我在这里附上截图,