在Listview中使用SwipeRefreshLayout无法向上滚动

Question

我想用ListView实现滚动刷新功能。此外，在同一布局文件中还有其他视图元素，如果列表为空，则会显示这些元素。这是我的布局文件。问题是，当我向下滚动，然后尝试向上滚动，而不是一直滚动到顶部，然后刷新它只是刷新那里，向上滚动是不起作用的。

<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/swipe_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="64dp"
        android:paddingLeft="16dp"
        android:paddingRight="16dp" >

        <ImageView
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:src="@drawable/inbox_empty" />

        <TextView
            android:id="@+id/noEventsText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:layout_marginLeft="16dp"
            android:layout_toRightOf="@+id/noEventsIcon" />

        <View
            android:id="@+id/divider"
            android:layout_width="match_parent"
            android:layout_height="1px"
            android:layout_alignParentBottom="true"
            android:layout_marginLeft="4dp"
            android:layout_marginRight="4dp"
            android:background="@color/dividerOnBlack" />
    </RelativeLayout>

    <ListView
        android:id="@+id/list_items"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"
        android:cacheColorHint="@android:color/transparent"
        android:choiceMode="multipleChoice"
        android:descendantFocusability="afterDescendants"
        android:divider="@android:color/transparent"
        android:dividerHeight="0px"
        android:scrollbars="none" />
</LinearLayout>

</android.support.v4.widget.SwipeRefreshLayout>

@Override
public void onScroll(AbsListView view,int firstVisibleItem,int visibleItemCount,int totalItemCount) {
    // If the total item count is zero and the previous isn't, assume the
    // list is invalidated and should be reset back to initial state
    if (totalItemCount < previousTotalItemCount) {
        this.currentPage = this.startingPageIndex;
        this.previousTotalItemCount = totalItemCount;
        if (totalItemCount == 0) { this.loading = true; } 
    }

    // If it's still loading, we check to see if the dataset count has
    // changed, if so we conclude it has finished loading and update the current page
    // number and total item count.
    if (loading && (totalItemCount > previousTotalItemCount)) {
        loading = false;
        previousTotalItemCount = totalItemCount;
        currentPage++;
    }

    // If reverse then the firstVisibleItem is calculated wrong
    if (reverse) {
        firstVisibleItem = totalItemCount - firstVisibleItem;
    }
    // If it isn't currently loading, we check to see if we have breached
    // the visibleThreshold and need to reload more data.
    // If we do need to reload some more data, we execute onLoadMore to fetch the data.
    if (!loading && (totalItemCount - visibleItemCount)<=(firstVisibleItem + visibleThreshold)) {
        onLoadMore(currentPage + 1, totalItemCount);
        loading = true;
    }
}

Answer 1

为了使SwipeRefreshLayout工作，它需要是您的ListView的直接父视图，并且ListView应该是SwipeRefreshLayout的第一个活动子视图。

SwipeRefreshLayout的文档说ListView应该是唯一的子级，但是如果它有多个子级，只要ListView是第一个，就可以了。例如，这意味着如果您使用的适配器的视图为“empty”，SwipeRefreshLayout将很好地工作。例如：

<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/swipe_refresh"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".NearbyJobsActivity$PlaceholderFragment">

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:divider="@color/list_divider"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/list_row_selector" />

    <TextView
        android:id="@android:id/empty"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center" />

</android.support.v4.widget.SwipeRefreshLayout>

如果您能够管理这种布局，那么SwipeRefreshLayout将会很好地工作，您将不需要其他答案中列出的任何变通方法。

我自己的问题是，我将ListView作为一个片段加载，因此我实际上有：

<SwipeRefreshLayout>

    <FrameLayout>           )
         <ListView/>        \ fragment
         <TextView/>        /
    </FrameLayout>          )

</SwipeRefreshLayout>

因此，SwipeRefreshLayout选择FrameLayout作为它的“目标”，其默认的CanChildScrollup()实现总是返回false。当我将SwipeRefreshLayout移动到片段内部时，一切都开始正常工作。

<FrameLayout>

    <SwipeRefreshLayout>    )
         <ListView/>        \ fragment
         <TextView/>        /
    </SwipeRefreshLayout>   )

</FrameLayout>