我正在尝试为Android TV制作一个基本的相册应用。
结合使用recyclerview。
问题： 按下dpad向下按钮缓慢滚动一遍时，recyclerview项将按预期准确地获得焦点。但是，当按住dpad向下按钮时，在快速滚动过程中，recyclerview项很容易失去焦点，并且焦点会移动到recyclerview之外的任何可聚焦视图（在这种情况下为编辑文本），并且除非手动将焦点移到recyclerview内，否则无法滚动再次。
尝试的补救措施： 1.如果我完全禁用了Glide的图像加载（在onBindViewHolder（）内部），则焦点永远不会丢失，并且无论滚动多么快都能正常工作。由于需要查看图像，因此该方法无用。 2.如果通过覆盖Activity.onKeyDown方法来限制快速滚动以忽略所有键输入，除非自上次按下键以来经过了300ms，否则它将起作用。再次，这感觉很棘手，完全禁止使用快速滚动。
请注意，我已经阅读了关于stackoverflow的相关质量检查。这表明这是Android支持库LayoutManager代码中的错误，在这里不是这种情况，因为无需滑动即可正常工作。
如何复制：创建一个类似ListFragment的片段（下面的代码），并通过按住Down Dpad按钮尝试快速滚动，您将看到editText不断成为焦点。
代码： ListFragment.java
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.bumptech.glide.Glide;
import com.bumptech.glide.RequestManager;
import com.bumptech.glide.request.RequestOptions;
import java.util.Random;
public class ListFragment extends Fragment {
RequestManager glide;
public ListFragment() {
// Required empty public constructor
}
private RecyclerView recyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager layoutManager;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_list, container, false);
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
recyclerView = getActivity().findViewById(R.id.my_recycler_view);
glide = Glide.with(this);
layoutManager = new GridLayoutManager(getActivity(),8);
mAdapter = new MyAdapter();
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(mAdapter);
}
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private final String[] imageUrls = 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private final RequestOptions options = new RequestOptions().centerCrop();
private final Random random = new Random();
private final Handler handler = new Handler();
public class ViewHolder extends RecyclerView.ViewHolder {
public ImageView icon;
public View layout;
ViewHolder(View v) {
super(v);
layout = v;
icon = v.findViewById(R.id.icon);
}
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
LayoutInflater inflater = LayoutInflater.from(
parent.getContext());
View v =
inflater.inflate(R.layout.item_recycler_view, parent, false);
MyAdapter.ViewHolder vh = new MyAdapter.ViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(final MyAdapter.ViewHolder holder, final int position) {
final String name = imageUrls[random.nextInt(imageUrls.length - 1)];
//Commenting this out resolves focus loss
glide.load(name).into(holder.icon);
}
@Override
public void onViewRecycled(@NonNull ViewHolder holder) {
super.onViewRecycled(holder);
glide.clear(holder.icon);
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
return Integer.MAX_VALUE;
}
}
}
布局： item_recycler_view.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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="wrap_content"
android:foreground="@drawable/fg_selectable"
android:clickable="true"
android:focusable="true"
android:focusableInTouchMode="false"
android:descendantFocusability="blocksDescendants"
android:layout_margin="2dp"
>
<ImageView
android:id="@+id/icon"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="27:41"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:background="@color/colorPrimaryDark"
tools:src="@tools:sample/avatars"
/>
</android.support.constraint.ConstraintLayout>
fragment_list.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".ListFragment"
android:orientation="horizontal"
>
<EditText
android:id="@+id/editText"
android:text="test"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:nextFocusDown="@id/editText"
/>
<android.support.v7.widget.RecyclerView
android:id="@+id/my_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</LinearLayout>
答案 0 :(得分：0)
为什么在onViewRecycled中需要glide.clear（）？我的猜测是它与快速滚动期间频繁的滑行加载和清除有关。滑行可能会变得有些混乱。另外，为什么不使用Leanback Library和GridFragment？根据我的经验，它可以与Glide和快速滚动一起很好地工作。