Drawer的父类为StatelessWidget，不可刷新，今天来讲一下刷新的办法
需求：点击A用户，弹出侧边栏，侧边栏展示用户的数据。
需要使用StreamBuilder。但是使用stream发数据是行不通的，因为数据传递不进去。
但是使用StreamBuilder依旧可以收到通知。所以流程就需要改变一下
一、点击按键后刷新Drawer并展示
1、使用StatefulWidget
2、在state里创建备用数据，本例为SSML ssml=SSML();
3、点击按键，更新备用数据：ssml = ssmlList[index];
4、通知StreamBuilder：streamController.add(‘event’);
5、StreamBuilder接到通知，使用备用数据重新构造

二、刷新Drawer面板上的内容
具体为使用StatefulBuilder自带的setState方法，不要使用公共的，作为区别，名字改为setStateB。代码片段为_changeRate方法

class DrawerTest extends StatefulWidget {final File file;const DrawerTest(this.file, {super.key});@overrideState createState() {return _DrawerTestState();}
}class _DrawerTestState extends State {SSML ssml = SSML();StreamController streamController = StreamController.broadcast();List ssmlList = [];@overridevoid initState() {ssmlList.add(SSML()..name = 'dan');ssmlList.add(SSML()..name = 'ada');super.initState();}final GlobalKey _ssKey = GlobalKey();@overrideWidget build(BuildContext context) {return Scaffold(key: _ssKey,drawer: _getDrawer(),appBar: AppBar(leading: IconButton(onPressed: () {Navigator.pop(context);},icon: const Icon(Icons.arrow_back)),title: const Text('Drawer测试'),),body: SafeArea(child: Container(color: Colors.white10,padding: const EdgeInsets.all(15),child: ListView.builder(itemCount: ssmlList.length,itemBuilder: (context, index) {return ElevatedButton(onPressed: () {ssml = ssmlList[index];streamController.add('event'); //通知StreamBuilder该刷新了_ssKey.currentState!.openDrawer();},child: Text('${ssmlList[index].name}打开左边栏'));}),)));}StreamBuilder _getDrawer() {return StreamBuilder(stream: streamController.stream,builder: (context, shot) {return Drawer(child: StatefulBuilder(builder: (context, setStateB) {return _changeRate(ssml);},));});}Widget _changeRate(SSML ssml) {return StatefulBuilder(builder: (context, setStateB) {return Row(mainAxisAlignment: MainAxisAlignment.spaceBetween,children: [Text('速度：${ssml.rate}'),Slider(value: ssml.rate.toDouble(),max: 500,min: -500,onChanged: (value) {setStateB(() {ssml.rate = value.toInt();});// setState(() {});})],);});}
}class SSML {late String name;int rate = 0;
}