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我正在学习颤振。我想用底部导航栏制作应用程序。我已经建立了带有 5 个选项卡的底部导航栏。其中之一是配置文件选项卡。我的情况是当我点击个人资料选项卡时，我的应用程序将检查用户是否已登录。如果用户没有登录，我的应用程序将使用和从 LoginPage 重定向到 LoginPage ，如果登录成功并且如果登录失败或用户点击应用程序栏上的后退按钮Navigator.push()，它将重定向回值。truefalse

之后在 ProfilePage 中，它检查 true 将显示配置文件，false 将重定向到上一页。

我正在使用 rxdart 和 BehaviourSubject 来更改索引页面。我成功更改了标签索引和标签正文。但我的应用程序不显示当前正文（点击配置文件选项卡之前的上一个选项卡）

主要.dart

import 'package:flutter/material.dart';
import 'package:usahaku_flutter/pages/HomePage.dart';
import 'package:usahaku_flutter/pages/ChatPage.dart';
import 'package:usahaku_flutter/pages/TransactionPage.dart';
import 'package:usahaku_flutter/pages/ProfilePage.dart';
import 'package:usahaku_flutter/pages/ShopPage.dart';
import './services/locator_service.dart';
import './blocs/NavTab.dart';

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

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MyAppState();
  }
}

class MyAppState extends State<MyApp> {
  final _pageOption = [
    HomePage(),
    ChatPage(),
    UserProfile(),
    TransactionPage(),
    ShopPage(),
  ];
  int _currentTabIndex = 0;
  var _currentPage;
  @override
  initState() {
    super.initState();
    _currentPage = _pageOption[_currentTabIndex];
    sl.get<NavTab>().subject_currentTab.listen((data) {
      _currentTabIndex = data;
      _currentPage = _pageOption[_currentTabIndex];
      print(_currentPage);
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'UsahaKu',
        theme: ThemeData(primarySwatch: Colors.brown),
        home: SafeArea(
          child: Scaffold(
            body: _currentPage,
            bottomNavigationBar: BottomNavigationBar(
                fixedColor: Colors.black87,
                currentIndex: _currentTabIndex,
                type: BottomNavigationBarType.fixed,
                items: [
                  BottomNavigationBarItem(
                    icon: Icon(Icons.home),
                    title: Text('Home'),
                  ),
                  BottomNavigationBarItem(
                    icon: Icon(Icons.chat),
                    title: Text('Chat'),
                  ),
                  BottomNavigationBarItem(
                    icon: Icon(Icons.person),
                    title: Text('Profile'),
                  ),
                  BottomNavigationBarItem(
                    icon: Icon(Icons.transform),
                    title: Text('Transaksi'),
                  ),
                  BottomNavigationBarItem(
                    icon: Icon(Icons.business_center),
                    title: Text('Toko'),
                  ),
                ],
                onTap: (index) {
                  setState(() {
                    sl.get<NavTab>().changeTab(index);
                  });
                }),
          ),
        ));
  }
}

导航标签.dart

import 'package:rxdart/rxdart.dart';

class NavTab {
  BehaviorSubject<int> subject_currentTab = new BehaviorSubject<int>();
  BehaviorSubject<int> subject_previousTab = new BehaviorSubject<int>();

  // Observable<int> currentTab;
  // Observable<int> previousTab;

  NavTab() {
    // currentTab = new Observable(subject_currentTab);
    // previousTab = new Observable(subject_previousTab);
    subject_currentTab.add(0);
    subject_previousTab.add(null);
  }

  void changeTab(int c) {
    var cr = subject_currentTab.value;
    var pr = subject_previousTab.value;
    if (cr != pr) {
      subject_previousTab.add(cr);
      subject_currentTab.add(c);
    }else{
      subject_currentTab.add(c);
    }
  }

  void backToPreviousTab() {
    var r = subject_previousTab.value;
    subject_currentTab.add(r);
  }
}

ProfilePage.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:usahaku_flutter/services/Auth.dart';
import 'package:usahaku_flutter/services/locator_service.dart';
import './LoginPage.dart';
import '../blocs/NavTab.dart';

class UserProfile extends StatefulWidget {
  @override
  UserProfileState createState() => UserProfileState();
}

class UserProfileState extends State<UserProfile> {
  Map<String, dynamic> _profile;
  StreamSubscription _profileSubs = null;

  @override
  initState() {
    super.initState();
    print('constructor');
    print('profile page');
    _profileSubs = sl.get<AuthService>().profile.listen((state) => setState(() {
          print('constructor');
          print('state');
          print(state);
          if (state == null) {
            print('navigate to loginpage');
            Navigator.push(context,
                MaterialPageRoute(builder: (context) => LoginPage())).then((t) {
              if (t == false) {
                sl.get<NavTab>().backToPreviousTab();
              }
            });
          } else {
            _profile = state;
          }
        }));
  }

  @override
  void dispose() {
    _profileSubs.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Profile'),
      ),
      body: Column(
        children: <Widget>[
          Text(_profile.toString()),
          MaterialButton(
            onPressed: () => sl.get<AuthService>().signOut(),
            child: Text('Logout'),
          )
        ],
      ),
    );
  }
}

登录页面.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:rxdart/rxdart.dart';
import 'package:usahaku_flutter/services/Auth.dart';
import '../services/locator_service.dart';

class LoginPage extends StatefulWidget {
  @override
  LoginPageState createState() => LoginPageState();
}

class LoginPageState extends State<LoginPage> {
  Observable _profileSubs = null;

  @override
  initState() {
    super.initState();
    _profileSubs = sl.get<AuthService>().user.switchMap((u) {
      if (u != null) {
        Navigator.pop(context, true);
      }
    });
  }

  @override
  void dispose() {
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          leading: IconButton(
            icon: Icon(Icons.chevron_left),
            onPressed: () => Navigator.pop(context, false),
          ),
          title: Text('Login'),
        ),
        body: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          mainAxisSize: MainAxisSize.max,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            MaterialButton(
              onPressed: () {
                sl.get<AuthService>().googleSignIn().then((value) {
                  if (value != null) {
                    Navigator.pop(context, true);
                  }
                });
              },
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                crossAxisAlignment: CrossAxisAlignment.center,
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[Icon(Icons.get_app), Text('Login')],
              ),
            )
          ],
        ));
  }
}
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1 回答 1

0

我通过更改代码意外地解决了这个问题

从

 sl.get<NavTab>().subject_currentTab.listen((data) {
      _currentTabIndex = data;
      _currentPage = _pageOption[_currentTabIndex];
      print(_currentPage);
    });

至

 sl.get<NavTab>().subject_currentTab.listen((data) {
      setState(() {
        _currentTabIndex = data;
        _currentPage = _pageOption[_currentTabIndex];
      });
    });
于 2019-05-15T11:10:11.743 回答