Flutter 监听应用程序路由堆栈变化

女爷i 2022-12-27 08:16 177阅读 0赞

很多时候我们需要监听路由堆栈的变化，这样可以自定义路由堆栈、方便分析异常日志等。

监听路由堆栈的变化使用 **RouteObserver** ，首先在 **MaterialApp** 组件中添加 `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(),
        );
      }
    }

监听页面设置如下：

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 为路由堆栈变化的回调。

从 A 页面跳转到 ARouteObserverDemo 页面，日志输出如下：

flutter: A-didPush route: /ARouteObserver

进入此页面只调用了 didPush。

从 ARouteObserverDemo 页面跳转到 BRouteObserverDemo 页面（同 ARouteObserverDemo 页面，设置了监听），日志输出如下：

flutter: A-didPushNext route: /ARouteObserver
    flutter: B-didPush route: /BRouteObserver

先调用了 ARouteObserverDemo 页面的 didPushNext，然后调用了 BRouteObserverDemo 页面的 didPush。

从 BRouteObserverDemo 页面执行 pop 返回 ARouteObserverDemo 页面，日志输出如下：

flutter: A-didPopNext route: /ARouteObserver
    flutter: B-didPop route: /BRouteObserver

先调用了 ARouteObserverDemo 页面的 didPopNext，然后调用了 BRouteObserverDemo 页面的 didPop。

上面的案例仅仅是页面级别的路由堆栈变化，如果想知道整个应用程序路由堆栈变化如何处理？

一种方法是写一个监听路由堆栈的基类，所有页面继承此基类。此方法对源代码的侵入性非常高。

还有一种方法是自定义 RouteObserver，继承RouteObserver并重写其中的方法：

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(),
        );
      }
    }

此时从 A 页面 跳转到 B 页面，日志输出如下：

flutter: didPush route: MaterialPageRoute<dynamic>(RouteSettings("/B", 来自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)))