migrate scaffold from stateful to stateless

lib/scaffold/as_scaffold.dart

@@ -14,7 +14,7 @@ import 'package:ansu_ui/buttons/as_back_button.dart';
 ///title , AppBar 和 AppBarBottom 均为 `null`时不显示scaffold的AppBar
 ///
 ///只有AppBarBottom时只显示AppBarBottom中的内容
-class ASScaffold extends StatefulWidget {
+class ASScaffold extends StatelessWidget {
   ///标题，可为`String`或`Text`
   final dynamic title;
 
@@ -58,30 +58,20 @@ class ASScaffold extends StatefulWidget {
     this.floatingActionButton,
   }) : super(key: key);
 
-  @override
-  _ASScaffoldState createState() => _ASScaffoldState();
+  Widget get _title {
+    if (title is String) return Text(title);
+    return title ?? SizedBox();
   }
 
-class _ASScaffoldState extends State<ASScaffold> {
-  @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      key: widget.key,
-      endDrawer: widget.endDrawer,
-      backgroundColor: widget.backgroundColor,
-      bottomNavigationBar: widget.bottomNavigationBar,
-      floatingActionButton: widget.floatingActionButton,
-      appBar: widget.title == null &&
-              widget.appBar == null &&
-              widget.appBarBottom == null
-          ? null
-          : widget.appBar ??
+  Widget get _appBar {
+    if (title == null && appBar == null && appBarBottom == null) return null;
+    return appBar ??
         AppBar(
           brightness: Brightness.light,
           backgroundColor: kForegroundColor,
           elevation: 0,
-                leading: widget.leading ?? ASBackButton(),
-                actions: widget.actions ?? [],
+          leading: leading ?? ASBackButton(),
+          actions: actions ?? [],
           centerTitle: true,
           title: DefaultTextStyle(
             style: TextStyle(
@@ -89,17 +79,26 @@ class _ASScaffoldState extends State<ASScaffold> {
               fontSize: 18.sp,
               fontWeight: FontWeight.bold,
             ),
-                  child: widget.title is String
-                      ? Text(widget.title)
-                      : widget.title ?? SizedBox(),
+            child: _title,
           ),
-                bottom: widget.appBarBottom ??
+          bottom: appBarBottom ??
               PreferredSize(
                 child: SizedBox(),
                 preferredSize: Size.fromHeight(0),
               ),
-              ),
-      body: widget.body,
+        );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      key: key,
+      endDrawer: endDrawer,
+      backgroundColor: backgroundColor,
+      bottomNavigationBar: bottomNavigationBar,
+      floatingActionButton: floatingActionButton,
+      appBar: _appBar,
+      body: body,
     );
   }
 }