优化

app/src/main/res/layout/view_book_page.xml

@@ -3,6 +3,7 @@
     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:id="@+id/vw_root"
     android:background="@color/background"
     android:layout_width="match_parent"
     android:layout_height="match_parent"