如何为 Stateful Widget 创建 Flutter 路由？

Question

我收到了我的 Flutter 应用程序的 Navigator operation requested with a context that does not include a Navigator. 错误日志。我看到的所有示例都是针对 "Stateless" 小部件的，所以我认为这可能是问题或我的代码？我怎样才能路由到我的 LoginPage？这是我的代码，没有任何导航器或路线...

 void main() {
      runApp(new MyApp());
    }

    final googleSignIn = new GoogleSignIn();
    final fb = FirebaseDatabase.instance.reference();
    final auth = FirebaseAuth.instance;

    class MyApp extends StatefulWidget {
      @override
      _MyAppState createState() => new _MyAppState();
    }

    class _MyAppState extends State<MyApp> {
      String _platformVersion = 'Unknown';

      @override
      initState() {
        super.initState();
        initPlatformState();
      }

      // Platform messages are asynchronous, so we initialize in an async method.
      initPlatformState() async {
        String platformVersion;
        // Platform messages may fail, so we use a try/catch PlatformException.
        try {
          platformVersion = await Myfavkpopflutter.platformVersion;
        } on PlatformException {
          platformVersion = 'Failed to get platform version.';
        }

        // If the widget was removed from the tree while the asynchronous platform
        // message was in flight, we want to discard the reply rather than calling
        // setState to update our non-existent appearance.
        if (!mounted) return;

        setState(() {
          _platformVersion = platformVersion;
        });
      }

      void MyFavAction() {
        setState(() {
          print("MYFAV");

    //      fb.child("messages").orderByValue().onChildAdded.listen((Event event) {
    //        print('Child added: ${event.snapshot.value}');
    //      });
        });
      }

      void SearchAction() {
        setState(() {
          print("Search");
        });
      }



      @override
      Widget build(BuildContext context) {
        if (auth.currentUser == null) {
          return new MaterialApp(
            routes: <String, WidgetBuilder>{
            '/settings': (BuildContext context) => new LoginPage(),
            },
            home: new Scaffold(
              backgroundColor: Colors.white70,
              appBar: new AppBar(
                title: new Text(
                  "MyFavKPop",
                  style: new TextStyle(
                      color: Colors.black,
                      fontWeight: FontWeight.bold,
                      fontSize: 25.00),
                ),
                backgroundColor: Colors.amber,
              ),
              body: new Container(
                  child: new Center(
                      child: new Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  new RaisedButton(
                    onPressed: MyFavAction,
                    color: Colors.lightBlue,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    child: new Text(
                      "MyFav KPOP",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(padding: new EdgeInsets.all(30.00)),
                  new RaisedButton(
                    onPressed: SearchAction,
                    color: Colors.lightBlue,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    child: new Text(
                      "MyFav SEARCH",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav FRIENDS",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(
                    padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav CHAT",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(
                    padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav #1'S",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  )
                ],
              ))),
              floatingActionButton: new FloatingActionButton(
                  child: new Text(
                    "Log Out",
                    style: new TextStyle(fontWeight: FontWeight.bold, fontSize: 12.00),
                  ),
                  onPressed: () => Navigator.of(context).pushNamed('/settings'),,
            ),
          ));
        } 
      }
    }

    class LoginPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Login / Signup"),
      ),
      body: new Container(
        child: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              new TextField(
                decoration: new InputDecoration(
                    hintText: "E M A I L    A D D R E S S"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new TextField(
                obscureText: true,
                decoration:
                new InputDecoration(hintText: "P A S S W O R D"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new TextField(
                decoration:
                new InputDecoration(hintText: "U S E R N A M E"),
              ),
              new RaisedButton(
                onPressed: null,
                child: new Text("SIGNUP"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("LOGIN"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("Facebook"),
              ),
              new Padding(padding: new EdgeInsets.all(5.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("Google"),
              )
            ],
          ),
        ),
        margin: new EdgeInsets.all(15.00),
      ),
    );
  }
}

**** 编辑这是我收到的错误日志...

══╡手势异常╞═══════════════════════════════════ ══════════════════════════════ 处理手势时抛出以下断言：使用不包含导航器的上下文请求的导航器操作。用于从导航器推送或弹出路由的上下文必须是一个小部件的上下文导航器小部件的后代。

═══════════════════════════════════════════ ══════════════════════════════════════════════════ ═════

Answer 1

此错误与有状态或无状态路由无关。您可以查看我的回答以获取工作示例。

顺便说一句：我在你的代码中找不到你对 Navigator 的调用。你如何以及在哪里调用推送？

编辑

您的应用程序中应该始终只有一个 MaterialApp。您可以为一个 MaterialApp 提供各种路由（参见我的示例）。

Answer 2

您在标题中说明您的问题是导航到 StatefulWidget，而在您的 post 中您询问如何导航到 StatelessWidget LoginPage。

无论如何，无论状态如何，您都应该能够以相同的方式实现导航。

尝试遵循以下流程，该流程取自我正在开发的应用程序。

//Local Imports
//MyTabs.dart is where I define my home page which is a StatefulWidget with TabBarView 
import 'MyTabs.dart' as first;

.....

//My main function where I start my app

    void main() {
      runApp( new MaterialApp(
        home: new SignIn(),
        routes: <String, WidgetBuilder>{
          "/mytabs" : (BuildContext context)=> new first.MyTabs(),
          //add more routes here
        },

      ));
    }

我的应用程序从一个登录页面开始，我创建了一个比展示想法更简单的页面

class SignIn extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
  return new Scaffold(
    appBar: new AppBar(
      title: new Text("Sign In"),
    ),
    body: new IconButton(icon: new Icon(Icons.arrow_forward), onPressed: (){Navigator.of(context).pushNamed("/mytabs");}),
  )

希望对您有所帮助，尝试在您的代码中遵循此流程，让我知道进展如何。

Answer 3

Navigator.of(context).push(new MaterialPageRoute(builder: 
                   (BuildContext context) => new MyTabs()));

对于导航，我们也可以使用上面的代码。

如何为 Stateful Widget 创建 Flutter 路由？

How to create Flutter route for Stateful Widget?

routes

class

navigator

flutter