[TOC] ## 概述 - Builder 用于獲取父組件或者部分狀態管理的方法 - 這個小部件是定義[StatelessWidget](https://api.flutter.dev/flutter/widgets/StatelessWidget-class.html)子類的簡單內聯替代方案 ``` class Foo extends StatelessWidget { @override Widget build(BuildContext context) => Text('foo'); } Center(child: Foo()) ``` 可用Builder替換 ``` Center( child: Builder( builder: (BuildContext context) => Text('foo'); ), ) ``` ``` child: Builder( builder: (context){ return TextButton( onPressed: (){ ScaffoldState _sate = context.findAncestorStateOfType<ScaffoldState>()!; _sate.closeDrawer(); }, child: Text("hello world"), ); }, ) ```