CustomView 的 ListView 到 RecyclerView 迁移

Question

我发现我的项目需要从 ListView 转移到 RecyclerView。我遇到了一些设计问题。

在我当前的 ListView 实现中，我使用 CustomView 而不是在那里膨胀。这是我当前的 getView()

public View getView(int position, View containerRow, ViewGroup parent) {
        CustomView customView;
        if (containerRow == null) customView = new CustomView(mContext);
        else customView = (CustomView) containerRow;

        DataModel dataModel = getModelForPosition(position);
        if (dataModel != null) {
            customView.showView(singleDcyde,position);
        }
        return customView;

}

此处 showView 管理填充文本视图、图像自定义 LayoutParams 以及许多其他内容（2000 行）。

现在我正计划转移到 RecylerView，我对我的设计有点困惑。 - 我是否需要在 RecyclerView.ViewHolder class 中重写整个内容，然后在 onBindViewHolder 中绑定它们？

因为我已经为 Listview 编写了大量代码，所以我不想 rewrite/move 将所有内容从 CustomView 返回到 ViewHolder。

保持设计与 RecyclerView 理念同步的最佳方法是什么。

Answer 1

将 ListView 适配器转换为 RecyclerView.Adapter 非常简单 - 我已经为以下两种实现编写了框架：

private static class MyRecyclerViewAdapter extends RecyclerView.Adapter<CustomViewHolder> {

    @Override
    public CustomViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        CustomView view = createNewCustomView();
        return new CustomViewHolder(view);
    }

    private CustomView createNewCustomView() {
        // whatever you need to do to create - I would suggest create from XML rather new'ing up directly
        return null;
    }

    @Override
    public void onBindViewHolder(CustomViewHolder holder, int position) {
        // bind the data
        DataModel dataModel = getModelForPosition(position);
        holder.getCustomView().showView(dataModel, position);
    }

    private DataModel getModelForPosition(int position) {
        // TODO: however you did getModelForPosition(int)
        return null;
    }

    @Override
    public int getItemCount() {
        // TODO: same as getCount()
        return 0;
    }

}

private static class CustomViewHolder extends RecyclerView.ViewHolder {

    public CustomViewHolder(CustomView itemView) {
        super(itemView);
    }

    CustomView getCustomView() {
        return ((CustomView) itemView);
    }

}

private static class MyListViewAdapter extends BaseAdapter {

    @Override
    public int getCount() {
        // TODO: return correct list size
        return 0;
    }

    @Override
    public DataModel getItem(int position) {
        // TODO: however you did getModelForPosition(int)
        return null;
    }

    @Override
    public long getItemId(int position) {
        // however you do
        return 0;
    }

    @Override
    public View getView(int position, View containerRow, ViewGroup parent) {
        CustomView customView = ((CustomView) containerRow);
        if (customView == null) {
            customView = createNewCustomView();
        }

        // could just use getItem(int) here
        DataModel dataModel = getModelForPosition(position);

        // would it ever be null? if so, you'll have a blank list item
        if (dataModel != null) {
            customView.showView(dataModel.getSingleDcyde(), position);
        }
        return customView;
    }

    private CustomView createNewCustomView() {
        // whatever you need to do to create - I would suggest create from XML rather new'ing up directly
        return null;
    }

    private DataModel getModelForPosition(int position) {
        return getItem(position);
    }

}

private static class DataModel {

    Object getSingleDcyde() {
        // whatever this is
        return null;
    }

}

private static class CustomView extends View {

    public CustomView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void showView(Object singleDcyde, int position) {
        // bind
    }

}

What is the best way to keep design in sync with RecyclerView philosophy.

RecyclerView 背后的理念是关注点分离； RecyclerView 仅负责管理视图回收，LayoutManager 将决定如何测量和定位视图，ViewHolder 试图强制使用 ViewHolder 模式（一种避免多次不必要地调用 findViewById() 的方法），以及 RecyclerView.Adapter 是连接数据的粘合剂。

您现在被迫使用 ViewHolder class。这个想法是每个膨胀布局 (whether or not this call is slow enough to bother doing is debated) 只执行一次所有 findViewById() 调用，例如：

private static final class CustomViewHolder extends RecyclerView.ViewHolder {

    private final TextView titleTextView;
    private final ImageView avatarImageView;

    public CustomViewHolder newInstance(CustomView itemView) {
        return new CustomViewHolder(
                itemView,
                ((TextView) itemView.findViewById(R.id.title_text_view)),
                ((ImageView) itemView.findViewById(R.id.avatar_image_view))
        );
    }

    private CustomViewHolder(CustomView itemView, TextView titleTextView, ImageView avatarImageView) {
        super(itemView);
        this.titleTextView = titleTextView;
        this.avatarImageView = avatarImageView;
    }

    public void setTitle(String title) {
        titleTextView.setText(title);
    }

    public void setAvatar(Drawable avatar) {
        avatarImageView.setImageDrawable(avatar);
    }

}

实际上，由于您使用的是自定义视图，很可能（我希望）您已经通过使用 HolderView pattern 避免了对 findViewById(int) 的多次调用。在这种情况下，您可以通过将其视为必要的邪恶来反抗强制使用 ViewHolder 的暴政：

private static final class CustomViewHolder extends RecyclerView.ViewHolder {

    public CustomViewHolder(CustomView itemView) {
        super(itemView);
    }

}

...
...

@Override
public void onBindViewHolder(CustomViewHolder holder, int position) {
    Foo foo = getFoo(position);
    ((CustomView) holder.itemView).myCustomBindMethod(foo);
}

CustomView 的 ListView 到 RecyclerView 迁移

ListView to RecyclerView Migration for CustomView

android

listview

android-listview

android-recyclerview