dart - 当小部件被路由到/离开时的类回调函数

Question

我正在寻找一种在我的小部件类中具有某种回调函数的方法。本质上，我正在寻找这样的东西:

class SomeWidget extends StatefulWidget with RouteHandlerMixin {
  // ...

  void onRouteTo(Route oldRoute) {
    // Do stuff before this widget gets routed to
    // Perhaps return a bool to approve/cancel the route
  }

  void onRouteAway(Route newRoute) {
    // Do stuff before this widget gets routed away from
    // Perhaps return a bool to approve/cancel the route
  }

  // ...
}

Flutter 是否支持这种行为？我能找到/想到的最接近的是一些简陋的解决方案，涉及将逻辑放在根 MaterialApp 的 onGenerateRoute 属性中。

Answer 1

你要找的是RouteAware

// Register the RouteObserver as a navigation observer.
final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>();
void main() {
  runApp(MaterialApp(
    home: Container(),
    navigatorObservers: [routeObserver],
  ));
}

class RouteAwareWidget extends StatefulWidget {
  State<RouteAwareWidget> createState() => RouteAwareWidgetState();
}

// Implement RouteAware in a widget's state and subscribe it to the RouteObserver.
class RouteAwareWidgetState extends State<RouteAwareWidget> with RouteAware {

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    routeObserver.subscribe(this, ModalRoute.of(context));
  }

  @override
  void dispose() {
    routeObserver.unsubscribe(this);
    super.dispose();
  }

  @override
  void didPush() {
    // Route was pushed onto navigator and is now topmost route.
  }

  @override
  void didPopNext() {
    // Covering route was popped off the navigator.
  }

  @override
  Widget build(BuildContext context) => Container();

}