Flutter InheritedWidget、provider数据共享

1.继承InheritedWidget定义需要共享的数据

class ShareDateWidget extends InheritedWidget {final String data;//需要共享的数据const ShareDateWidget({Key? key, required Widget child, required this.data}): super(key: key, child: child);//获取当前共享的数据，方便使用者访问static ShareDateWidget? of(BuildContext context) =>context.dependOnInheritedWidgetOfExactType<ShareDateWidget>();@overridebool updateShouldNotify(covariant ShareDateWidget oldWidget) =>//判断改变的数据和原来的数据是否是相同的，如果不相同则返回true通知子树中依赖data的Widget重新build//返回true就会重新build否则不会//同时如果返回false使用者的didChangeDependencies方法也不会被调用oldWidget.data != data;
}

2.定义两个使用者

class _TestWidget extends StatefulWidget {@overrideState<StatefulWidget> createState() => _TestWidgetState();
}
class _TestWidgetState extends State<_TestWidget> {@overrideWidget build(BuildContext context) =>Text('Widget Top：${ShareDateWidget.of(context)?.data ?? ""}');@overridevoid didChangeDependencies() {super.didChangeDependencies();if (kDebugMode) {print("Dependencies change");}}
}

class _Test2Widget extends StatefulWidget {@overrideState<StatefulWidget> createState() => _Test2WidgetState();
}class _Test2WidgetState extends State<_Test2Widget> {@overrideWidget build(BuildContext context) =>Text('Widget Bottom：${ShareDateWidget.of(context)?.data ?? ""}');@overridevoid didChangeDependencies() {super.didChangeDependencies();if (kDebugMode) {print("Dependencies change");}}
}

如果使用者共享使用的InheritedWidget的数据就会回调使用者didChangeDependencies方法

3.实现一个按钮点击改变ShareDateWidget的共享数据

class _TestPage extends StatefulWidget {@overrideState<StatefulWidget> createState() => _TestPageState();
}class _TestPageState extends State<_TestPage> {String text = "text ";@overrideWidget build(BuildContext context) => MaterialApp(home: Scaffold(body: ShareDateWidget(data: text,child: Container(alignment: Alignment.center,child: Column(mainAxisAlignment: MainAxisAlignment.center,children: [_TestWidget(),ElevatedButton(onPressed: () {setState(() {text = '当前时间：${DateTime.now()}';});},child: const Text('改变数据')),_Test2Widget(),],),),),),);
}

最后出来的效果就是只要点击按钮就会改变ShareDateWidget的data数据：

按照InheritedWidget的逻辑官方还提供了一个provider

1.创建数据共享模板：

引入插件pubspec.yaml

dependencies:provider: ^6.0.2

数据共享模板

class HomeMode extends ChangeNotifier {String homeData = "正在获取...";void getHomeData() {//通过接口获取数据callGET(ServiceUrl.home, result: (result) {//获取数据正常，发送通过更新数据homeData = result.toString();notifyListeners();}, resultErr: (error, stark) {homeData = error.toString();notifyListeners();});}
}

2.使用数据

使用数据最外层用ChangeNotifierProvider包裹

class HomeNewPage extends StatelessWidget {const HomeNewPage({Key? key}) : super(key: key);@overrideWidget build(BuildContext context) => ChangeNotifierProvider(create: (context) => HomeMode(),child: const HomeNewWidget(),);
}

订阅数据

class HomeNewWidget extends StatefulWidget {const HomeNewWidget({Key? key}) : super(key: key);@overrideState<StatefulWidget> createState() => HomeState();
}class HomeState extends State<HomeNewWidget> {@overridevoid initState() {super.initState();//请求获取数据context.read<HomeMode>().getHomeData();}@overrideWidget build(BuildContext context) => Scaffold(body: Container(alignment: Alignment.center,child: Text(context.watch<HomeMode>().homeData),),);
}