android - ScrollToPosition() 在带有图像的 RecyclerView 上效果不佳

Question

我有一个像这样的 RecyclerView 页面:

 <android.support.v7.widget.RecyclerView
                    android:id="@+id/rv_chat"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

RecyclerView item的xml是一个ImageView:

<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/iv_chat_item_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:maxHeight="@dimen/height_xl"
        android:maxWidth="@dimen/width_l"
        android:scaleType="centerInside"
        android:src="?attr/chat_image_loading" />

适配器:

public ChatAdapter(Context context, List<String> urls)
{
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

         //download image from internet
         downloadImage(url);
    }
}

主要 Activity :

    //image urls
    List<String> urls;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        //initialize recyclerview
        chatListView = (RecyclerView) findViewById(R.id.rv_chat);
        chatListView.setHasFixedSize(true);
        chatListView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
        chatListView.setItemAnimator(new DefaultItemAnimator());

        chatAdapter = new ChatAdapter(this,null);
        chatListView.setAdapter(chatAdapter);

        //add datas
        chatAdapter.addDatas(urls);

        //scroll to bottom
        chatListView.smoothScrollToPosition(chatListView.getBottom());
    }

我只是想这样做:下载图片后，让recyclerview滚动到底部。但是由于异步加载图片，recyclerview无法正确滚动到底部——它只是滚动到中间。那么我该怎么做才能让它正常工作呢？

Answer 1

下载前获取图片大小，并在 View 中设置空白图片。