[移动开发]android：RecyclerView刷新，页面自动滚动

?布局排版很简单，是ScrollView里嵌套了一个LinearLayout，在LinearLayout有个RecyclerView，RecyclerView每次刷新数据后会出现自动向上滚动的现象。解决办法如下：

 
    <androidx.core.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
       <!--父布局加了 android:descendantFocusability="blocksDescendants"-->
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:descendantFocusability="blocksDescendants"
            android:orientation="vertical">

            <View.../>

            <View .../>

            <!--子布局加了android:overScrollMode="never"-->
            <androidx.recyclerview.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:overScrollMode="never"
                app:layoutManager="LinearLayoutManager" />

            <Button ... />
        </LinearLayout>
    </androidx.core.widget.NestedScrollView>

?android:descendantFocusability具体含义

        <!-- Defines the relationship between the ViewGroup and its descendants
             when looking for a View to take focus. -->
        <attr name="descendantFocusability">
            <!-- The ViewGroup will get focus before any of its descendants. -->
            <enum name="beforeDescendants" value="0" />
            <!-- The ViewGroup will get focus only if none of its descendants want it. -->
            <enum name="afterDescendants" value="1" />
            <!-- The ViewGroup will block its descendants from receiving focus. -->
            <enum name="blocksDescendants" value="2" />
        </attr>

android:overScrollMode具体含义

 <!-- Defines over-scrolling behavior. This property is used only if the
             View is scrollable. Over-scrolling is the ability for the user to
             receive feedback when attempting to scroll beyond meaningful content. -->
        <attr name="overScrollMode">
            <!-- Always show over-scroll effects, even if the content fits entirely
                 within the available space. -->
            <enum name="always" value="0" />
            <!-- Only show over-scroll effects if the content is large
                 enough to meaningfully scroll. -->
            <enum name="ifContentScrolls" value="1" />
            <!-- Never show over-scroll effects. -->
            <enum name="never" value="2" />
        </attr>