android - onNestedScroll 未使用自定义 BottomNavigationViewBehavior 调用

Question

我想实现滚动时隐藏 BottomNavigationView。在谷歌上搜索解决方案，因为 android 框架似乎不存在一个可以开箱即用的解决方案，我当前的设置如下:

<android.support.design.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"
    tools:context=".MainActivity">

    <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="auto_fit"
        android:gravity="center"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottomNavigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:menu="@menu/menu_main">
    </android.support.design.widget.BottomNavigationView>
</android.support.design.widget.CoordinatorLayout>

主 Activity :

CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) bottomNavigation.getLayoutParams();
layoutParams.setBehavior(new BottomNavigationViewBehavior());

BottomNavigationViewBehavior:

public class BottomNavigationViewBehavior extends CoordinatorLayout.Behavior<BottomNavigationView> {

    private int height;

    @Override
    public boolean onLayoutChild(CoordinatorLayout parent, BottomNavigationView child, int layoutDirection) {
        height = child.getHeight();
        return super.onLayoutChild(parent, child, layoutDirection);
    }

    @Override
    public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
                                   BottomNavigationView child, @NonNull
                                           View directTargetChild, @NonNull View target,
                                   int axes, int type) {
        return axes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }

    @Override
    public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, 
    @NonNull BottomNavigationView child,
                           @NonNull View target, int dxConsumed, int dyConsumed,
                           int dxUnconsumed, int dyUnconsumed,
                           @ViewCompat.NestedScrollType int type) {
        if (dyConsumed > 0) {
            slideDown(child);
        } else if (dyConsumed < 0) {
            slideUp(child);
        }
    }

    private void slideUp(BottomNavigationView child) {
        child.clearAnimation();
        child.animate().translationY(0).setDuration(200);
    }

    private void slideDown(BottomNavigationView child) {
        child.clearAnimation();
        child.animate().translationY(height).setDuration(200);
    }
}

每次都会调用onLayoutChild，父级是CoordinatorLayout，子级是BottomNavigationView。但 onStartNestedScroll 和 onNestedScroll 从未被调用，因此底部导航 View 不会在滚动时隐藏。尝试切换布局 - fragment ，没有 fragment ，尝试通过 xml 布局设置行为，但没有任何效果。我在这里缺少什么？

Answer 1

您的 xml 应如下所示:

<android.support.design.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"
    tools:context=".MainActivity">

    <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="auto_fit"
        android:gravity="center"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:nestedScrollingEnabled="true"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottomNavigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:menu="@menu/menu_main"
        app:layout_behavior="BottomNavigationViewBehavior ">
    </android.support.design.widget.BottomNavigationView>
</android.support.design.widget.CoordinatorLayout>

放弃这部分:

    CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) bottomNavigation.getLayoutParams();
    layoutParams.setBehavior(new BottomNavigationViewBehavior());

你有一个类似的例子here

附言您还应该更改 GridView 并将 RecyclerView 与 GridLayoutManager 一起使用，就像您看到的那样 here