如何修改Launcher3 抽屉模式的recyclerview为横向分页排列

要将Launcher3抽屉模式的RecyclerView改为横向分页排列，可以按照以下步骤进行操作：

1. 打开Launcher3的源代码，找到抽屉的布局文件`apps_customize_pane.xml`，该文件中包含了RecyclerView的定义。

2. 找到RecyclerView的定义，将其布局方向修改为横向：

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

3. 在LayoutManager中设置横向分页排列：

   RecyclerView appsCustomizePane = (RecyclerView) findViewById(R.id.apps_customize_pane);
   LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
   appsCustomizePane.setLayoutManager(layoutManager);
   appsCustomizePane.setHasFixedSize(true);

4. 在Adapter中修改ViewHolder的布局和绑定逻辑，使其支持横向排列：

   public class AppViewHolder extends RecyclerView.ViewHolder {
       public TextView tvTitle;
       public ImageView ivIcon;

       public AppViewHolder(View itemView) {
           super(itemView);
           tvTitle = (TextView) itemView.findViewById(R.id.tv_title);
           ivIcon = (ImageView) itemView.findViewById(R.id.iv_icon);
       }

       public void bind(AppInfo appInfo) {
           tvTitle.setText(appInfo.title);
           ivIcon.setImageDrawable(appInfo.icon);
       }
   }

   @Override
   public AppViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
       View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_app, parent, false);
       itemView.setLayoutParams(new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
       return new AppViewHolder(itemView);
   }

   @Override
   public void onBindViewHolder(AppViewHolder holder, int position) {
       AppInfo appInfo = appList.get(position);
       holder.bind(appInfo);
   }

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

这样就可以将Launcher3抽屉模式的RecyclerView改为横向分页排列了。