我正在关注flutter'sdocumentationabouttheBuildContextclass因为我不清楚如何以及为什么要使用这个类。Widgetbuild(BuildContextcontext){//here,Scaffold.of(context)returnsnullreturnScaffold(appBar:AppBar(title:Text('Demo')),body:Builder(builder:(BuildContextcontext){returnFlatButton(child:Text('BUTTON'),onPressed:(){//here,Sca

我正在关注flutter'sdocumentationabouttheBuildContextclass因为我不清楚如何以及为什么要使用这个类。Widgetbuild(BuildContextcontext){//here,Scaffold.of(context)returnsnullreturnScaffold(appBar:AppBar(title:Text('Demo')),body:Builder(builder:(BuildContextcontext){returnFlatButton(child:Text('BUTTON'),onPressed:(){//here,Sca