很多時候我們需要監聽路由堆棧的變化,這樣可以自定義路由堆棧、方便分析異常日誌等。
監聽路由堆棧的變化使用 RouteObserver ,首先在 MaterialApp 組件中添加 navigatorObservers
:
void main() {
runApp(MyApp());
}
RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>();
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
...
navigatorObservers: [routeObserver],
home: HomePage(),
);
}
}
監聽頁面設置如下:
class ARouteObserverDemo extends StatefulWidget {
@override
_RouteObserverDemoState createState() => _RouteObserverDemoState();
}
class _RouteObserverDemoState extends State<ARouteObserverDemo> with RouteAware {
@override
void didChangeDependencies() {
super.didChangeDependencies();
routeObserver.subscribe(this, ModalRoute.of(context));
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
alignment: Alignment.center,
child: RaisedButton(
child: Text('A RouteObserver'),
onPressed: () {
Navigator.of(context).pushNamed('/BRouteObserver');
},
),
),
);
}
@override
void dispose() {
super.dispose();
routeObserver.unsubscribe(this);
}
@override
void didPush() {
final route = ModalRoute.of(context).settings.name;
print('A-didPush route: $route');
}
@override
void didPopNext() {
final route = ModalRoute.of(context).settings.name;
print('A-didPopNext route: $route');
}
@override
void didPushNext() {
final route = ModalRoute.of(context).settings.name;
print('A-didPushNext route: $route');
}
@override
void didPop() {
final route = ModalRoute.of(context).settings.name;
print('A-didPop route: $route');
}
}
其中 didPush、didPushNext、didPopNext、didPop 爲路由堆棧變化的回調。
從 A 頁面跳轉到 ARouteObserverDemo 頁面,日誌輸出如下:
flutter: A-didPush route: /ARouteObserver
進入此頁面只調用了 didPush。
從 ARouteObserverDemo 頁面跳轉到 BRouteObserverDemo 頁面(同 ARouteObserverDemo 頁面,設置了監聽),日誌輸出如下:
flutter: A-didPushNext route: /ARouteObserver
flutter: B-didPush route: /BRouteObserver
先調用了 ARouteObserverDemo 頁面的 didPushNext,然後調用了 BRouteObserverDemo 頁面的 didPush。
從 BRouteObserverDemo 頁面執行 pop 返回 ARouteObserverDemo 頁面,日誌輸出如下:
flutter: A-didPopNext route: /ARouteObserver
flutter: B-didPop route: /BRouteObserver
先調用了 ARouteObserverDemo 頁面的 didPopNext,然後調用了 BRouteObserverDemo 頁面的 didPop。
上面的案例僅僅是頁面級別的路由堆棧變化,如果想知道整個應用程序路由堆棧變化如何處理?
一種方法是寫一個監聽路由堆棧的基類,所有頁面繼承此基類。此方法對源代碼的侵入性非常高。
還有一種方法是自定義 RouteObserver,繼承RouteObserver並重寫其中的方法:
class MyRouteObserver<R extends Route<dynamic>> extends RouteObserver<R> {
@override
void didPush(Route route, Route previousRoute) {
super.didPush(route, previousRoute);
print('didPush route: $route,previousRoute:$previousRoute');
}
@override
void didPop(Route route, Route previousRoute) {
super.didPop(route, previousRoute);
print('didPop route: $route,previousRoute:$previousRoute');
}
@override
void didReplace({Route newRoute, Route oldRoute}) {
super.didReplace(newRoute: newRoute, oldRoute: oldRoute);
print('didReplace newRoute: $newRoute,oldRoute:$oldRoute');
}
@override
void didRemove(Route route, Route previousRoute) {
super.didRemove(route, previousRoute);
print('didRemove route: $route,previousRoute:$previousRoute');
}
@override
void didStartUserGesture(Route route, Route previousRoute) {
super.didStartUserGesture(route, previousRoute);
print('didStartUserGesture route: $route,previousRoute:$previousRoute');
}
@override
void didStopUserGesture() {
super.didStopUserGesture();
print('didStopUserGesture');
}
}
使用:
void main() {
runApp(MyApp());
}
MyRouteObserver<PageRoute> myRouteObserver = MyRouteObserver<PageRoute>();
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
navigatorObservers: [myRouteObserver],
initialRoute: '/A',
home: APage(),
);
}
}
此時從 A 頁面 跳轉到 B 頁面,日誌輸出如下:
flutter: didPush route: MaterialPageRoute<dynamic>(RouteSettings("/B", 來自A), animation: AnimationController#6d429(▶ 0.000; for MaterialPageRoute<dynamic>(/B))),previousRoute:MaterialPageRoute<dynamic>(RouteSettings("/A", null), animation: AnimationController#e60f7(⏭ 1.000; paused; for MaterialPageRoute<dynamic>(/A)))