fantik's questions

授权后，将颁发用户令牌，并保存该令牌。如果它在本地存储中可用并且在关闭应用程序后，则不需要进一步授权。这里一切正常，但是有一个 CreatePage 类，它再次需要一个令牌，我在从本地存储中获取它时遇到问题（尽管如果我直接将它插入代码中，它可以工作），服务器返回错误：“401 Unauthorized ”。flutter_secure_storage 库用于存储令牌。

AuthPage.dart

import 'dart:convert';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:localstorage/localstorage.dart';
import 'package:http/http.dart' as http;
import 'package:digitalpendal/main.dart';
import 'package:digitalpendal/screens/Authentication/RegistrationPage.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class AuthPage extends StatefulWidget {
  @override
  _AuthPageState createState() => _AuthPageState();
}

class _AuthPageState extends State<AuthPage> {
  String _email;
  String _password;
  final LocalStorage storage = new LocalStorage('some_key');
  final _sizeTextBlack = const TextStyle(fontSize: 20.0, color: Colors.black);
  final _sizeTextWhite = const TextStyle(fontSize: 20.0, color: Colors.white);
  final formKey = new GlobalKey<FormState>();
  BuildContext _context;


  @override
  Widget build(BuildContext context) {
    _context = context;
    return new MaterialApp(
      debugShowCheckedModeBanner: false,
      home: new Scaffold(
        body: new Center(
          child: new Form(
              key: formKey,
              child: new Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  new Container(
                    child: new TextFormField(
                      decoration: new InputDecoration(
                        labelText: "Логин",
                        fillColor: Colors.white,
                        border: new OutlineInputBorder(
                          borderRadius: new BorderRadius.circular(25.0),
                          borderSide: new BorderSide(),
                        ),
                        //fillColor: Colors.green
                      ),
                      keyboardType: TextInputType.emailAddress,
                      maxLines: 1,
                      style: _sizeTextBlack,
                      onSaved: (val) => _email = val,
                      validator: (val) =>
                          !val.contains("@") ? 'Not a valid email.' : null,
                    ),
                    width: 340.0,
                    height: 50,
                    padding: new EdgeInsets.only(top: 10.0),
                  ),
                  new Padding(padding: new EdgeInsets.only(top: 25.0)),
                  new Container(
                    child: new TextFormField(
                      decoration: new InputDecoration(
                        labelText: "Пароль",
                        fillColor: Colors.white,
                        border: new OutlineInputBorder(
                          borderRadius: new BorderRadius.circular(25.0),
                          borderSide: new BorderSide(),
                        ),
                        //fillColor: Colors.green
                      ),
                      obscureText: true,
                      maxLines: 1,
                      validator: (val) =>
                          val.length < 2 ? 'Password too short.' : null,
                      onSaved: (val) => _password = val,
                      style: _sizeTextBlack,
                    ),
                    width: 340.0,
                    height: 50,
                    padding: new EdgeInsets.only(top: 10.0),
                  ),
                  new Padding(
                    padding: new EdgeInsets.only(top: 25.0),
                    child: new MaterialButton(
                      onPressed: submit,
                      color: Theme.of(context).accentColor,
                      height: 50.0,
                      minWidth: 150.0,
                      child: new Text(
                        "Войти",
                        style: _sizeTextWhite,
                      ),
                    ),
                  ),
                  new Padding(
                    padding: new EdgeInsets.only(top: 25.0),
                    child: new MaterialButton(
                      onPressed: submitForm,
                      color: Colors.white,
                      height: 50.0,
                      minWidth: 150.0,
                      child: new Text(
                        "Зарегистрироваться",
                        style: _sizeTextBlack,
                      ),
                    ),
                  ),
                ],
              )),
        ),
      ),
    );
  }

  void submit() {
    final form = formKey.currentState;
    if (form.validate()) {
      form.save();
      signIn();
    }
  }

  void login() {
    final form = formKey.currentState;
    if (form.validate()) {
      form.save();
      submitForm();
    }
  }

  signIn() async {
    final storage = new FlutterSecureStorage();
    Map data = {
      'email': _email,
      'password': _password
    };
    var jsonResponse = null;
    var response = await http.post("http://192.168.0.104:8000/api/v1/auth_token/token/login/", body: data);
    if(response.statusCode == 200) {
      jsonResponse = json.decode(response.body);
      if(jsonResponse != null) {
        setState(() {

        });
        await storage.write(key: "auth_token", value: 'auth_token');
        Navigator.of(_context).pushAndRemoveUntil(MaterialPageRoute(builder: (BuildContext context) => MyBottomNavigationBar()), (Route<dynamic> route) => false);
      }
    }
    else {
      setState(() {

      });
      print(response.body);
    }
  }

  void hideKeyboard() {
    SystemChannels.textInput.invokeMethod('TextInput.hide');
  }
  void fucktheAuth(){
    hideKeyboard();
    Navigator.push(_context,
        new MaterialPageRoute(builder: (context) => new MyBottomNavigationBar()));
  }



  void submitForm() {
    hideKeyboard();
    Navigator.push(_context,
        new MaterialPageRoute(builder: (context) => new RegistrationPage()));
  }
}

主要.dart

import 'package:digitalpendal/TaskPage.dart';
import 'package:digitalpendal/screens/Authentication/AuthPage.dart';
import 'package:digitalpendal/screens/Create_page/CreatePage.dart';
import 'package:digitalpendal/screens/Profile_Page.dart';
import 'package:flutter/material.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(

      theme: ThemeData(primaryColor: Colors.blue.shade900),
      debugShowCheckedModeBanner: false,
      home: MyBottomNavigationBar(),
    );
  }
}

class MyBottomNavigationBar extends StatefulWidget {
  @override
  _MyBottomNavigationBarState createState() => _MyBottomNavigationBarState();
}

class _MyBottomNavigationBarState extends State<MyBottomNavigationBar> {
  final storage = FlutterSecureStorage();

  @override
  void initState(){
    super.initState();
    checkLoginStatus();
  }

  checkLoginStatus() async {
    String value = await storage.read(key: 'auth_token');
    if(value == null) {
      Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (BuildContext context) => AuthPage()), (Route<dynamic> route) => false);
    }
  }
  int _currentIndex = 0;
  final List<Widget> _children = [TaskPage(), CreatePage(), Profile_Page()];

  void onTappedBar(int index) {
    setState(() {

      _currentIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(

        resizeToAvoidBottomPadding: false,
        body: _children[_currentIndex],
        bottomNavigationBar: BottomNavigationBar(
          onTap: onTappedBar,
          currentIndex: _currentIndex,

          backgroundColor: Color.fromRGBO(48, 63, 159, 1),

          items: [
            BottomNavigationBarItem(

              icon: new Icon(
                  Icons.dashboard,
                  size: 35,
                  color: Colors.white,
                  ),

              title: new Text(
                '',
                style: new TextStyle(fontSize: 0, color: Colors.white),
              ),
              activeIcon: Theme(
                data: ThemeData(
                  accentColor: Color.fromRGBO(70, 116, 190, 1),
                ),
                child: FloatingActionButton(
                  elevation: 0,
                  onPressed: () {},
                  child: Icon(
                      Icons.dashboard,
                      size: 35,
                      color: Colors.white,),
                ),
              ),
            ),
            BottomNavigationBarItem(
                icon: new Icon(
                  Icons.add_circle,
                  size: 35,
                  color: Colors.white,
                ),
                title: new Text(
                  '',
                  style: new TextStyle(color: Colors.white, fontSize: 0),
                ),
              activeIcon: Theme(
                data: ThemeData(
                  accentColor: Color.fromRGBO(70, 116, 190, 1),
                ),
                child: FloatingActionButton(
                  elevation: 0,
                  onPressed: () {},
                  child: Icon(
                    Icons.add_circle,
                    size: 35,
                    color: Colors.white,),
                ),
              ),

            ),
            BottomNavigationBarItem(
                icon: new Icon(Icons.account_circle,
                    size: 35, color: Colors.white),
                title: new Text(
                  '',
                  style: new TextStyle(fontSize: 0, color: Colors.white),
                ),
              activeIcon: Theme(
                data: ThemeData(
                  accentColor: Color.fromRGBO(70, 116, 190, 1),
                ),
                child: FloatingActionButton(
                  elevation: 0,
                  onPressed: () {},
                  child: Icon(
                    Icons.account_circle,
                    size: 35,
                    color: Colors.white,),
                ),
              ),
            ),
          ],
        ));
  }
}

创建页面.dart

import 'dart:convert';

import 'package:digitalpendal/main.dart';
import 'package:digitalpendal/screens/Authentication/AuthPage.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:localstorage/localstorage.dart';
import 'package:shared_preferences/shared_preferences.dart';


class CreatePage extends StatefulWidget {
  @override
  _CreatePageState createState() => _CreatePageState();
}

class _CreatePageState extends State<CreatePage> {


 // final LocalStorage storage = new LocalStorage('some_key');
  final formKey = new GlobalKey<FormState>();

  String _name;
  String _description;
  String _countPeople;
  String _cost;
  String _executePeriod;
  String value;



  final _sizeTextBlack = const TextStyle(fontSize: 20.0, color: Colors.black);
  final _sizeTextWhite = const TextStyle(fontSize: 20.0, color: Colors.white);
  final storage = FlutterSecureStorage();



  @override
  void initState(){
    super.initState();
    checkLoginStatus();
  }

  checkLoginStatus() async {
    String value = await storage.read(key: 'auth_token');
    if(value == null) {
      Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (BuildContext context) => AuthPage()), (Route<dynamic> route) => false);
    }
  }


  BuildContext _context;
  @override
  Widget build(BuildContext context) {
    _context = context;
    return new MaterialApp(
        debugShowCheckedModeBanner: false,
        home: new Scaffold(
          resizeToAvoidBottomPadding: false,
          body: new Center(
            child: SingleChildScrollView(
              child: new Form(
                  key: formKey,
                  child: new Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      new Padding(padding: EdgeInsets.only(top: 20.0)),
                      new Container(
                        child: new TextFormField(
                          decoration: new InputDecoration(
                            labelText: "Название работы",
                            fillColor: Colors.white,
                            border: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(),
                            ),
                            //fillColor: Colors.green
                          ),
                          maxLines: 1,
                          validator: (val) =>
                          val.length < 2 ? 'Ввидите название' : null,
                          onSaved: (val) => _name = val,
                          style: _sizeTextBlack,
                        ),
                        width: 340.0,
                        height: 50,
                        margin: new EdgeInsets.only(top: 20.0),
                      ),
                      new Container(
                        child: new TextFormField(
                          decoration: new InputDecoration(
                            labelText: "Сколько людей нужно",
                            fillColor: Colors.white,
                            border: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(),
                            ),
                            //fillColor: Colors.green
                          ),
                          maxLines: 1,
                          validator: (val) =>
                          val.length < 0 ? 'количество меньше 0' : null,
                          onSaved: (val) => _countPeople = val,
                          style: _sizeTextBlack,
                        ),
                        width: 340.0,
                        height: 50,
                        margin: new EdgeInsets.only(top: 20.0),
                      ),
                      new Container(
                        child: new TextFormField(
                          decoration: new InputDecoration(
                            labelText: "Ввидите сумму",
                            fillColor: Colors.white,
                            border: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(),
                            ),
                            //fillColor: Colors.green
                          ),
                          maxLines: 1,
                          validator: (val) =>
                          val.length < 0 ? 'сумма мала' : null,
                          onSaved: (val) => _cost = val,
                          style: _sizeTextBlack,
                        ),
                        width: 340.0,
                        height: 50,
                        margin: new EdgeInsets.only(top: 20.0),
                      ),
                      new Container(
                        child: new TextFormField(
                          decoration: new InputDecoration(
                            labelText: "Срок исполнения",
                            fillColor: Colors.white,
                            border: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(),
                            ),
                            //fillColor: Colors.green
                          ),
                          maxLines: 1,
                          validator: (val) =>
                          val.length < 0 ? 'Введиnt срок выполнения' : null,
                          onSaved: (val) => _executePeriod = val,
                          style: _sizeTextBlack,
                        ),
                        width: 340.0,
                        height: 50,
                        margin: new EdgeInsets.only(top: 20.0),
                      ),
                      new Container(
                        child: new TextFormField(
                          decoration: new InputDecoration(
                            labelText: "краткое описание",
                            fillColor: Colors.white,
                            border: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(),
                            ),
                            //fillColor: Colors.green
                          ),
                          maxLines: 1,
                          validator: (val) =>
                          val.length < 2 ? 'Введите описание' : null,
                          onSaved: (val) => _description = val,
                          style: _sizeTextBlack,
                        ),
                        width: 340.0,
                        height: 50,
                        margin: new EdgeInsets.only(top: 20.0),
                      ),

                      new Padding(padding: new EdgeInsets.only(top: 50.0)),
                      new MaterialButton(
                        onPressed: submit,
                        color: Theme.of(context).accentColor,
                        height: 50.0,
                        minWidth: 150.0,
                        child: new Text(
                          "Создать",
                          style: _sizeTextWhite,
                        ),
                      ),
                    ],
                  )),
            ),
          ),
        ));
  }

  void submit() {
    final form = formKey.currentState;
    if (form.validate()) {
      form.save();
      performLogin(form);
    }
  }



  void performLogin(form) async {
    hideKeyboard();

    http.Response response = await http.post(
        Uri.encodeFull(
            'http://192.168.0.104:8000/api/v1/jobs/job/create/'),
        headers: {
          'Accept': 'application/json',
          //'Authorization': 'Token 82b6a5bcf7ad37f45de2a3e89bfea52f23bfb87a'//admin worked hardcore
          'Authorization':  value
        },
        body: {
          'name': _name,
          'description': _description,
          'count_people': _countPeople,
          'cost': _cost,
          'execute_period': _executePeriod
        });
    if (response.statusCode == 201) {
      //storage.setItem('user', jsonEncode(response.body));
      hideKeyboard();
      Navigator.push(_context,
          new MaterialPageRoute(builder: (context) => new MyBottomNavigationBar()));
    }
  }



  void hideKeyboard() {
    SystemChannels.textInput.invokeMethod('TextInput.hide');
  }
}

痛了好久，不知道怎么解决。应用程序启动，但是理论上，当您单击 gridView 元素时，应该会显示一个带有图片的窗口，但是当您单击它时，它会显示错误异常捕获的手势“Navigator operation requested with a context that does not包括一个导航器。”

主要.dart

import 'package:flutter/material.dart';
import 'details.dart';
import 'services.dart';
import 'album.dart';
import 'cell.dart';
import 'dart:async';

void main()=>runApp(GridViewDemo());

class GridViewDemo extends StatefulWidget {

  final String title = "Photos";

  @override
  GridViewDemoState createState() => GridViewDemoState();

}

class GridViewDemoState extends State<GridViewDemo> {
  //
  StreamController<int> streamController = new StreamController<int>();

  gridview(AsyncSnapshot<List<Album>> snapshot) {
      return Padding(
        padding: EdgeInsets.all(5.0),
        child: GridView.count(
          crossAxisCount: 2,
          childAspectRatio: 1.0,
          mainAxisSpacing: 4.0,
          crossAxisSpacing: 4.0,
          children: snapshot.data.map(
                (album) {
              return GestureDetector(
                child: GridTile(
                  child: AlbumCell(album),
                ),
                onTap: () {
                 goToDetailsPage(context, album);
                },
              );
            },
          ).toList(),
        ),

      );
  }

  goToDetailsPage(BuildContext context, Album album) {
    Navigator.push(
      context,
      MaterialPageRoute(
        fullscreenDialog: true,
        builder: (BuildContext context) => GridDetails(
          curAlbum: album,
        ),
      ),
    );

  }


  circularProgress() {
    return Center(
      child: const CircularProgressIndicator(),
    );
  }


  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: StreamBuilder(
            initialData: 0,
            stream: streamController.stream,
            builder: (BuildContext context, AsyncSnapshot snapshot) {
              return Text('${widget.title} ${snapshot.data}');
            },
          )),
       body: Column(
        mainAxisAlignment: MainAxisAlignment.start,
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          Flexible(
            child: FutureBuilder<List<Album>>(
              future: Services.getPhotos(),
              builder: (context, snapshot) {
                // not setstate here
                //
                if (snapshot.hasError) {
                  return Text('Error ${snapshot.error}');
                }
                //
                if (snapshot.hasData) {
                  streamController.sink.add(snapshot.data.length);
                  // gridview
                  return gridview(snapshot);
                }

                return circularProgress();
              },
            ),
          ),
        ],
      ),
    ),
    );
  }

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

细胞飞镖

import 'package:flutter/material.dart';
import 'album.dart';

class AlbumCell extends StatelessWidget {
  const AlbumCell(this.album);
  @required
  final Album album;

  @override
  Widget build(BuildContext context) {
    return Card(
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(10.0),
      ),
      color: Colors.white,
      child: Padding(
        padding: EdgeInsets.all(10.0),
        child: Container(
          alignment: Alignment.center,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisAlignment: MainAxisAlignment.center,
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Flexible(
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(10.0),
                  child: Hero(
                    tag: "image${album.id}",
                    child: FadeInImage.assetNetwork(
                      placeholder: "images/no_image.png",
                      image: album.thumbnailUrl,
                      width: 100,
                      height: 100,
                    ),
                  ),
                ),
              ),
              Padding(
                padding: EdgeInsets.all(10.0),
                child: Text(
                  album.title,
                  maxLines: 1,
                  softWrap: true,
                  textAlign: TextAlign.center,
                  style: TextStyle(
                    fontSize: 20.0,
                    fontWeight: FontWeight.w500,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

专辑.dart

class Album {


int albumId;
  int id;
  String title;
  String url;
  String thumbnailUrl;

  Album({this.albumId, this.id, this.title, this.url, this.thumbnailUrl});

  factory Album.fromJson(Map<String, dynamic> json) {
    return Album(
      albumId: json['albumId'] as int,
      id: json['id'] as int,
      title: json['title'] as String,
      url: json['url'] as String,
      thumbnailUrl: json['thumbnailUrl'] as String,
    );
  }
}

服务.dart

    import 'dart:convert';
import 'package:http/http.dart' as http;
import 'album.dart';

class Services {
  static const String url = "https://jsonplaceholder.typicode.com/photos";

  static Future<List<Album>> getPhotos() async {
    try {
      http.Response response = await http.get(
        Uri.encodeFull(url)
      );
      if (response.statusCode == 200) {
        List<Album> list = parsePhotos(response.body);
        return list;
      } else {
        throw Exception("Error");
      }
    } catch (e) {
      throw Exception(e.toString());
    }
  }

  static List<Album> parsePhotos(String responseBody) {
    final parsed = json.decode(responseBody).cast<Map<String, dynamic>>();
    return parsed.map<Album>((json) => Album.fromJson(json)).toList();
  }
}

细节.dart

import 'package:flutter/material.dart';
import 'album.dart';

class GridDetails extends StatefulWidget {
  final Album curAlbum;
  GridDetails({@required this.curAlbum});

  @override
  GridDetailsState createState() => GridDetailsState();
}

class GridDetailsState extends State<GridDetails> {
  //
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        alignment: Alignment.center,
        margin: EdgeInsets.all(30.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.center,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Hero(
              tag: "image${widget.curAlbum.id}",
              child: FadeInImage.assetNetwork(
                placeholder: "images/no_image.png",
                image: widget.curAlbum.url,
              ),
            ),
            SizedBox(
              height: 30.0,
            ),
            OutlineButton(
              child: Icon(Icons.close),
              onPressed: () => Navigator.of(context).pop(),
            ),
          ],
        ),
      ),
    );
  }
}

有一个 ChangeTheme 类，它有一个切换小部件，可以改变应用程序的主题，但是如果你转到另一个屏幕，然后再次返回带有开关的屏幕，它将不会再次处于活动状态。此外，如果您关闭应用程序，则由开关设置的主题将被重置。如何解决？

更改主题.dart

import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:todo/theme.dart';
import 'package:provider/provider.dart';



class ChangeTheme extends StatefulWidget{

  ChangeTheme({Key key, this.title}): super(key: key);
  final String title;
  @override
  MyState createState() => new MyState ();

}


class MyState extends State<ChangeTheme>{
  bool val = false;
  String message = "смена темы";
  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;

  @override
  Widget build(BuildContext context){
    set();
    return new Scaffold(

        appBar: AppBar(
          title: Text('Настройки'),
        ),
        body: Container(
            child: Column(
              children: <Widget>[
               new Switch(
                 value: val,
                 onChanged: (bool e) => setState(() => something(e)),
                ),
                new Text (message),

                ],
              ),
      ),
    );
  }

 void something(bool e) {
   ThemeChanger _themeChanger = Provider.of<ThemeChanger>(context);
    setState(() {

      if (e){
        _themeChanger.setTheme(ThemeData.dark());
        message = "Темнаяя тема";
        val = e;
        get();

      } else {
        _themeChanger.setTheme(ThemeData.light());
        message = "Светлая тема";
        val = e;
        get();
      }
    });
 }
  get() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    final myBool = prefs.getBool('my_bool_key') ?? false;
  }
  set() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool('my_bool_key', true);
  }

}

主要.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'theme.dart';
import 'ChangeTheme.dart';
import 'Constants.dart';

void main() async => runApp(new TodoApp());

class TodoApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<ThemeChanger>(
      builder: (_) => ThemeChanger(ThemeData.light()),
      child: new MaterialAppWithTheme (
      ),
    );
  }
}

class MaterialAppWithTheme extends StatelessWidget {

  @override
  Widget build(BuildContext context) {

    final theme = Provider.of<ThemeChanger>(context);

    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: new TodoList(),
      theme: theme.getTheme(),
    );
  }

}

class TodoList extends StatefulWidget {
  @override
  createState() => new TodoListState();
}

class TodoListState extends State<TodoList> {

  List<String> _todoItems = [];



  @override
  Widget build(BuildContext context) {
    _getPrefs();
    return new Scaffold(
      appBar: new AppBar(title: new Text('Список задач'),
      actions: <Widget>[
      PopupMenuButton<String>(
       onSelected: choiceAction ,
        itemBuilder: (BuildContext context){
         return Constants.choices.map((String choice){
            return PopupMenuItem<String>(
            value: choice,
              child: Text(choice),
            );
         }).toList();
        },
      )
      ]),
      body: _buildTodoList(),

      floatingActionButton: new FloatingActionButton(
          onPressed: _addTodoItem,
          tooltip: 'Add task',
          child: new Icon(Icons.add)),
    );
  }

  Widget _buildTodoList() {
    return new ListView.builder(itemBuilder: (context, index) {
      if (index < _todoItems.length) {
        return _buildTodoItem(_todoItems[index], index);
      }
    });
  }


 void choiceAction(String choice){
    if (choice == Constants.ChangeTheme){
      _changeTheme();


    }

    else if (choice == Constants.OffAd){
      showDialog(
          context: context,
          builder: (BuildContext context) {
            return new AlertDialog(
                title: new Text('Хочешь отключить рекламу?\n\n'
                    'Разработчку и дизайнеру тоже хочеца кушатб, '
                    'поэтому для отключения рекламы отправь деняк. '),
                actions: <Widget>[
                  new FlatButton(
                      child: new Text('подробнее'),
                      onPressed: () => Navigator.of(context).pop()),
                  new FlatButton(
                      child: new Text('нет я жмот'),
                      onPressed: () => Navigator.of(context).pop()),
                ]);
          });


    } else if (choice == Constants.info){
      showDialog(
          context: context,
          builder: (BuildContext context) {
            return new AlertDialog(
                title: new Text('Todo\n'
                                'Разбработчик:  \n'
                                'Дизайнер:  \n'
                                ),
                actions: <Widget>[
                  new FlatButton(
                      child: new Text('оценить'),
                      onPressed: () => Navigator.of(context).pop()),
                  new FlatButton(
                      child: new Text('отмена'),
                      onPressed: () => Navigator.of(context).pop()),
                ]);
          });

    }
 }

 void _changeTheme(){
   Navigator.push(context,
       new MaterialPageRoute(
           builder: (context) => new ChangeTheme()));
 }



  Widget _buildTodoItem(String todoText, int index) {
    return new ListTile(
        title: new Text(todoText), onTap: () => _removeTodoItem(index));
  }

  void _addTodoItem() {
    // Push this page onto the stack
    Navigator.of(context).push(new MaterialPageRoute(builder: (context) {
      return new Scaffold(
          appBar: new AppBar(title: new Text('добавление задачи')),
          body: new TextField(
            autofocus: true,
            onSubmitted: (val) {
              _addItem(val);
              Navigator.pop(context); // Close the add todo screen
            },
            decoration: new InputDecoration(
                hintText: 'Введите вашу задачу',
                contentPadding: const EdgeInsets.all(16.0)),
          ));
    }));
  }

  void _addItem(String task) {
    if (task.length > 0) {
      setState(() => _todoItems.add(task));
      _setPrefs();
    }
  }

  void _removeTodoItem(int index) {
    showDialog(
        context: context,
        builder: (BuildContext context) {
          return new AlertDialog(
              title: new Text('Задача "${_todoItems[index]}" выполнена?'),
              actions: <Widget>[
                new FlatButton(
                    child: new Text('отмена'),
                    onPressed: () => Navigator.of(context).pop()),
                new FlatButton(
                    child: new Text('выполнена'),
                    onPressed: () {
                      _removeItem(index);
                      Navigator.of(context).pop();
                    })
              ]);
        });
  }

  void _removeItem(int index) {
    setState(() => _todoItems.removeAt(index));
    _setPrefs();
  }

  void _setPrefs() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setStringList('TodoList', _todoItems);
  }

  void _getPrefs() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    if (prefs.getStringList('TodoList') != null)
      _todoItems = prefs.getStringList('TodoList');
  }

}

主题.dart

import 'package:flutter/material.dart';

class ThemeChanger with ChangeNotifier {
  ThemeData _themeData;

  ThemeChanger(this._themeData);

  getTheme() => _themeData;
  setTheme(ThemeData theme) {
    _themeData = theme;

    notifyListeners();
  }
}

常量.dart

 class Constants {
  static const String ChangeTheme = 'Настройки';
  static const String info = 'Информация';
  static const String OffAd = 'Отключить рекламу';

  static const List<String> choices = <String>[
    ChangeTheme,
    info,
    OffAd
  ];

}

我有一个用颤振编写的 TODO 应用程序，我希望在关闭应用程序时保存列表视图中添加的文本。听说可以添加共享偏好，但是最近在编程，不知道怎么实现。main.dart

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';


void main() => runApp(new TodoApp());


class TodoApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
        debugShowCheckedModeBanner: false,
        title: 'Todo List',
        home: new TodoList()
    );
  }
}

class TodoList extends StatefulWidget {
  @override
  createState() => new TodoListState();
}

class TodoListState extends State<TodoList> {
  String _haveStarted3Times = '';
  List<String> _todoItems = [];

  void _addTodoItem(String task) {
    if(task.length > 0) {

      setState(() => _todoItems.add(task));
    }
  }

  void _removeTodoItem(int index) {
    setState(() => _todoItems.removeAt(index));
  }

  void _promptRemoveTodoItem(int index) {
    showDialog(
        context: context,
        builder: (BuildContext context) {
          return new AlertDialog(
              title: new Text('Задача "${_todoItems[index]}" выполнена?'),
              actions: <Widget>[
                new FlatButton(
                    child: new Text('отмена'),
                    onPressed: () => Navigator.of(context).pop()
                ),
                new FlatButton(
                    child: new Text('выполнена'),
                    onPressed: () {
                      _removeTodoItem(index);
                      Navigator.of(context).pop();
                    }
                )
              ]
          );
        }
    );
  }


  Widget _buildTodoList() {
    return new ListView.builder(
      itemBuilder: (context, index) {
        if(index < _todoItems.length) {
          return _buildTodoItem(_todoItems[index], index);
        }
      },
    );
  }

  Widget _buildTodoItem(String todoText, int index) {
    return new ListTile(
        title: new Text(todoText),
        onTap: () => _promptRemoveTodoItem(index)
    );
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
          title: new Text('Todo List')
      ),
      body: _buildTodoList(),
      floatingActionButton: new FloatingActionButton(
          onPressed: _pushAddTodoScreen,
          tooltip: 'Add task',
          child: new Icon(Icons.add)
      ),
    );
  }

  void _pushAddTodoScreen() {
    // Push this page onto the stack
    Navigator.of(context).push(
        new MaterialPageRoute(
            builder: (context) {
              return new Scaffold(
                  appBar: new AppBar(
                      title: new Text('добавление задачи')
                  ),
                  body: new TextField(
                    autofocus: true,
                    onSubmitted: (val) {
                      _addTodoItem(val);
                      Navigator.pop(context); // Close the add todo screen
                    },
                    decoration: new InputDecoration(
                        hintText: 'Введите вашу задачу',
                        contentPadding: const EdgeInsets.all(16.0)
                    ),
                  )
              );
            }
        )
    );
  }
}

我有一个带有 centos 7 的虚拟服务器，安装了 nginx + php-fpm，我无法配置 nginx 配置，以便在切换到域时处理 .php 文件，但是，在切换到域时，它提供下载一个带有 php 脚本的文件。

server {
    listen   80;
    server_name  myapptest.gq;
        root   /usr/share/nginx/html;
        index  index.php;

    #charset koi8-r;
    #access_log  /var/log/nginx/host.access.log  main;

    #location / {
     #   root   /usr/share/nginx/html;
      #  index  index.php index.html index.htm;
    #}

        #location / {
        #   try_files $uri $uri/ /index.php?q=$uri&$args;
        #}
    #location ~* ^.+.(js|css|png|jpg|jpeg|gif|ico)$ {
        #   access_log        off;
        #   expires           max;
        #}

    #error_page  404              /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    #
    #location ~ \.php$ {
    #    proxy_pass   http://127.0.0.1;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    location ~ \.php$ {
        root php;
        #fastcgi_param  DOCUMENT_ROOT    /myapptest.gq;
        #fastcgi_pass unix:/var/run/php-fpm.sock;
        #fastcgi_pass 127.0.0.1:9000;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
       include        fastcgi_params;
    }

    # deny access to .htaccess files, if Apache's document root
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    #
    #location ~ \.php$ {
    #    proxy_pass   http://127.0.0.1;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    location ~ \.php$ {
        root php;
        #fastcgi_param  DOCUMENT_ROOT    /myapptest.gq;
        #fastcgi_pass unix:/var/run/php-fpm.sock;
        #fastcgi_pass 127.0.0.1:9000;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
       include        fastcgi_params;
    }

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #    deny  all;
    #}
}

有一个“创建任务”按钮，当您单击它时，会出现“俄语”按钮，如果您单击它，则会创建一个新活动并将我们转移到它。问题：如何实现，以便在单击按钮时，会出现一个附有新活动的按钮。

创建BottomTabActivity和一个带有 xml 文件的片段。我连接了所有这些，当我在片段的 xml 文件中创建一个常规按钮时，它会出现在这个 BottomTab 中，无论我放在哪里。我不知道怎么了。

 MainActivity.xml

<?xml version="1.0" encoding="utf-8"?>
  <android.support.constraint.ConstraintLayout  xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<android.support.design.widget.BottomNavigationView
    android:id="@+id/navigation"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:background="?android:attr/windowBackground"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:menu="@menu/navigation" />

</android.support.constraint.ConstraintLayout>


  MainActivity.class



public class MainActivity extends AppCompatActivity {



private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
                  account account = new account();
                FragmentManager manager = getSupportFragmentManager();
                manager.beginTransaction().replace(R.id.navigation, account, account.getTag()).commit();
                return true;
            case R.id.navigation_dashboard:

                return true;
            case R.id.navigation_notifications:

                return true;
        }
        return false;
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}

}