在RecyclerView中设置CardView的背景图像会导致程序在滚动时崩溃

Question

我有一个包含CardViews列表的RecyclerView，其中包含从服务器提取的信息，一些卡片只有背景颜色，但有些卡片包含背景图像。如果所有的卡片都只有背景颜色，RecyclerView就会有相应的行为(我还可以设置边距和边角半径)。但是，如果任何一张卡包含背景图像，当我尝试向上/向下滚动列表时，将发生崩溃(尽管加载背景图像时将不使用先前设置的角半径)。

以下是崩溃日志：

java.lang.ClassCastException: android.graphics.drawable.BitmapDrawable cannot be cast to android.support.v7.widget.RoundRectDrawable
        at android.support.v7.widget.CardViewApi21.setBackgroundColor(CardViewApi21.java:107)
        at android.support.v7.widget.CardView.setCardBackgroundColor(CardView.java:234)
        at co.roverlabs.sdk.ui.CardListAdapter.onBindViewHolder(CardListAdapter.java:88)
        at co.roverlabs.sdk.ui.CardListAdapter.onBindViewHolder(CardListAdapter.java:28)
        at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:4402)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3717)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3609)
        at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1859)
        at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1311)
        at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1274)
        at android.support.v7.widget.LinearLayoutManager.scrollBy(LinearLayoutManager.java:1102)
        at android.support.v7.widget.LinearLayoutManager.scrollVerticallyBy(LinearLayoutManager.java:959)
        at android.support.v7.widget.RecyclerView$ViewFlinger.run(RecyclerView.java:3062)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
        at android.view.Choreographer.doCallbacks(Choreographer.java:580)
        at android.view.Choreographer.doFrame(Choreographer.java:549)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

下面是我的onBindViewHolder()方法(为了便于阅读，使用了硬编码的值进行了简化)：

public void onBindViewHolder(final CardViewHolder holder, int position) {

    //Set margins
    CardView.LayoutParams cardLayoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 2000);
    cardLayoutParams.setMargins(20, 20, 20, 20);
    holder.cardView.setLayoutParams(cardLayoutParams);

    //Set background color or image
    if(view.hasBackgroundImage()) {
        holder.cardView.setBackground(R.drawable.background);
    }
    else {
        holder.cardView.setCardBackgroundColor(Color.CYAN);
    }

    //Set border radius
    holder.cardView.setRadius(20);

    //Set elevation
    holder.cardView.setCardElevation(0);

下面是我的onCreateViewHolder()方法和自定义Recycler.ViewHolder方法：

public CardViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

    View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view, parent, false);
    return new CardViewHolder(itemView);
}

public class CardViewHolder extends RecyclerView.ViewHolder {

    protected CardView cardView;

    public CardViewHolder(View view) {

        super(view);
        cardView = (CardView)view.findViewById(R.id.single_card_view);
    }
}

最后，下面是我的CardView的XML文件：

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/single_card_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:id="@+id/single_card_view_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </RelativeLayout>

</android.support.v7.widget.CardView>

我只想知道如何将CardView的背景设置为自定义图像，而不仅仅是颜色，以及是否有任何解决方法。对我来说能够设置卡片的角半径是很重要的。谢谢!

Answer 1

假设你使用的是CardView，你的不能改变背景可绘制，因为CardView使用背景可绘制来绘制卡片。您可以通过setCardBackgroundColor更改卡片背景颜色。