最近小弟实现了， 一款相册， 但是在实现流水线的时候，recycleview 嵌套 recycleview 加载图片的时候，内存迟迟没法销毁。 导致占用内存到 2g. 下面贴一贴我的代码

public class PhotoAdapter extends RecyclerView.Adapter<PhotoAdapter.ViewHolder> {

    private Context context;
    private List<PhotoGroup> photoGroupList;

    // 构造方法（将图片数据传入）
    public PhotoAdapter(List<PhotoGroup> photoGroupList) {
        this.photoGroupList = photoGroupList;
    }


    @Override
    public int getItemViewType(int position) {
        if (position == 0) {
            return 0;
        }
        return -1;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        if (context == null) {
            context = parent.getContext();
        }
        // 返回外层 分组的 item
        View view = LayoutInflater.from(context).inflate(R.layout.image_group_item, parent, false);
        final ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onViewRecycled(@NonNull ViewHolder holder) {
        super.onViewRecycled(holder);
        Glide.with(holder.itemView).clear(holder.itemView);
        Glide.with(holder.itemView).clear(holder.cardView);
        Glide.with(holder.itemView).clear(holder.recyclerView);
    }

    //将数据绑定到控件上
    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        PhotoGroup PhotoGroup = photoGroupList.get(position);

        ChildAdapter childAdapter = (ChildAdapter) holder.recyclerView.getAdapter();
        if (childAdapter == null) {
            // 设定 image_group_item 布局（每列显示 4 个子布局 image_child_item ）
            GridLayoutManager manager = new GridLayoutManager(context, 4);
            holder.recyclerView.setItemViewCacheSize(2000);
            holder.recyclerView.setHasFixedSize(true);
            holder.recyclerView.setNestedScrollingEnabled(false);
            holder.recyclerView.setLayoutManager(manager);
            // 设置子布局的适配器  [ PhotoGroup.getPhotoArrayList() 是一个分组中的图片数据] 
            holder.recyclerView.setAdapter(new ChildAdapter(PhotoGroup.getPhotoArrayList()));
        } else {
            // 重用子布局的适配，如果已经初始化过，直接调用 notifyDataSetChanged() 刷新布局就行
            childAdapter.setData(PhotoGroup.getPhotoArrayList());
//            childAdapter.notifyDataSetChanged();
        }

    }

    @Override
    public int getItemCount() {
        return photoGroupList.size();
    }

    // ViewHolder 对应 image_group_item 文件，里面元素只有最外层 CardView 和一个嵌套 RecyclerView
    static class ViewHolder extends RecyclerView.ViewHolder {
        RelativeLayout cardView;
        RecyclerView recyclerView;

        public ViewHolder(View view) {
            super(view);
            cardView = (RelativeLayout) view;
            recyclerView = (RecyclerView) view.findViewById(R.id.tupian_item_recyclerView);
            recyclerView.addOnScrollListener(new ImageAutoLoadScrollListener(view.getContext()));
        }
    }

    /*****************************ChildAdapter ***************************************/
    // 嵌套子适配（内部类）
    public class ChildAdapter extends RecyclerView.Adapter<ChildViewHolder> {

        // 每一个组的图片数据
        private ArrayList<Photo> photoList;

        //构造函数
        public ChildAdapter(ArrayList<Photo> photoList) {
            this.photoList = photoList;
        }

        //用于更新图片数据
        public void setData(ArrayList<Photo> photoList) {
            this.photoList = photoList;
        }

        @NonNull
        @Override
        public ChildViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            if (context == null) {
                context = parent.getContext();
            }
            View view = LayoutInflater.from(context).inflate(R.layout.image_child_item, parent, false);
            final ChildViewHolder holder = new ChildViewHolder(view);
            return holder;

        }

        @Override
        public void onViewRecycled(@NonNull ChildViewHolder holder) {
            super.onViewRecycled(holder);
            Glide.with(holder.itemView.getContext()).clear(holder.imageView);
        }

        @Override
        public void onBindViewHolder(@NonNull ChildViewHolder holder, int position) {
            Photo image = photoList.get(position);

            Uri uri = ContentUris.withAppendedId(
                    UriUtil.INSTANCE.getMediaType(image.getMediaType()),
                    image.getId()
            );
            Glide.with(holder.imageView.getContext())
                    .asDrawable()
                    .load(uri)
                    .thumbnail(0.1f)
                    .override(SizeUtils.dp2px(100), SizeUtils.dp2px(100))
                    .placeholder(R.drawable.folder_ripple)
                    .format(DecodeFormat.PREFER_RGB_565)
                    .skipMemoryCache(true)
                    .into(holder.imageView);
        }

        @Override
        public int getItemCount() {
            return photoList.size();
        }

    }
}

下面是我流水线布局的代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/main_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/image_child_item_id"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="2dp"
    app:cardCornerRadius="4dp">

    <com.example.pic.picmanager.MyRoundImageView
        android:id="@+id/image_item_imageView"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:adjustViewBounds="true"
        android:scaleType="centerCrop"
        app:round="4dp" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/image_group_item_id"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:cardCornerRadius="4dp"
    app:cardElevation="0dp">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/tupian_item_recyclerView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>