为什么我尝试启动它时我的Android应用程序崩溃？

时间：2020-07-20 15:18:47

标签： flutter dart

我开发了一个android应用程序，它在模拟器中可以正常工作。但是，当我尝试在移动设备上启动它时，无论是在调试模式还是发行版中，它都崩溃了。为什么会这样？

main.dart：

import 'dart:async';
import 'dart:math';
import 'dart:ui';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

import 'package:flutter/services.dart' show SystemChrome, DeviceOrientation;
import 'package:intl/intl.dart' show DateFormat;

// Vertretungsplan Montag 

class VPMontag extends StatelessWidget {
  String url;
  VPMontag(this.url);

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Vertretungsplan Montag'),
        ),
        body: Builder(builder: (BuildContext context) {
          return WebView(
            initialUrl: url,
            javascriptMode: JavascriptMode.unrestricted,
            onWebViewCreated: (WebViewController webViewController) {
              _controller.complete(webViewController);
            },
            navigationDelegate: (NavigationRequest request) {
              if (request.url.startsWith('https://www.youtube.com/')) {
                print('blocking navigation to $request}');
                return NavigationDecision.prevent;
              }
              print('allowing navigation to $request');
              return NavigationDecision.navigate;
            },
            onPageStarted: (String url) {
              print('Page started loading: $url');
            },
            onPageFinished: (String url) {
              print('Page finished loading: $url');
            },
            gestureNavigationEnabled: true,
          );
        }));
  }
}

// VP Dienstag 

class VPDienstag extends StatelessWidget {
  String url;
  VPDienstag(this.url);

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Vertretungsplan Dienstag'),
        ),
        body: Builder(builder: (BuildContext context) {
          return WebView(
            initialUrl: url,
            javascriptMode: JavascriptMode.unrestricted,
            onWebViewCreated: (WebViewController webViewController) {
              _controller.complete(webViewController);
            },
            navigationDelegate: (NavigationRequest request) {
              if (request.url.startsWith('https://www.youtube.com/')) {
                print('blocking navigation to $request}');
                return NavigationDecision.prevent;
              }
              print('allowing navigation to $request');
              return NavigationDecision.navigate;
            },
            onPageStarted: (String url) {
              print('Page started loading: $url');
            },
            onPageFinished: (String url) {
              print('Page finished loading: $url');
            },
            gestureNavigationEnabled: true,
          );
        }));
  }
}

// VP Mittwoch 

class VPMittwoch extends StatelessWidget {
  String url;
  VPMittwoch(this.url);

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Vertretungsplan Mittwoch'),
        ),
        body: Builder(builder: (BuildContext context) {
          return WebView(
            initialUrl: url,
            javascriptMode: JavascriptMode.unrestricted,
            onWebViewCreated: (WebViewController webViewController) {
              _controller.complete(webViewController);
            },
            navigationDelegate: (NavigationRequest request) {
              if (request.url.startsWith('https://www.youtube.com/')) {
                print('blocking navigation to $request}');
                return NavigationDecision.prevent;
              }
              print('allowing navigation to $request');
              return NavigationDecision.navigate;
            },
            onPageStarted: (String url) {
              print('Page started loading: $url');
            },
            onPageFinished: (String url) {
              print('Page finished loading: $url');
            },
            gestureNavigationEnabled: true,
          );
        }));
  }
}

// VP Donnerstag 

class VPDonnerstag extends StatelessWidget {
  String url;
  VPDonnerstag(this.url);

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Vertretungsplan Donnerstag'),
        ),
        body: Builder(builder: (BuildContext context) {
          return WebView(
            initialUrl: url,
            javascriptMode: JavascriptMode.unrestricted,
            onWebViewCreated: (WebViewController webViewController) {
              _controller.complete(webViewController);
            },
            navigationDelegate: (NavigationRequest request) {
              if (request.url.startsWith('https://www.youtube.com/')) {
                print('blocking navigation to $request}');
                return NavigationDecision.prevent;
              }
              print('allowing navigation to $request');
              return NavigationDecision.navigate;
            },
            onPageStarted: (String url) {
              print('Page started loading: $url');
            },
            onPageFinished: (String url) {
              print('Page finished loading: $url');
            },
            gestureNavigationEnabled: true,
          );
        }));
  }
}

// VP Freitag 

class VPFreitag extends StatelessWidget {
  String url;
  VPFreitag(this.url);

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Vertretungsplan Freitag'),
        ),
        body: Builder(builder: (BuildContext context) {
          return WebView(
            initialUrl: url,
            javascriptMode: JavascriptMode.unrestricted,
            onWebViewCreated: (WebViewController webViewController) {
              _controller.complete(webViewController);
            },
            navigationDelegate: (NavigationRequest request) {
              if (request.url.startsWith('https://www.youtube.com/')) {
                print('blocking navigation to $request}');
                return NavigationDecision.prevent;
              }
              print('allowing navigation to $request');
              return NavigationDecision.navigate;
            },
            onPageStarted: (String url) {
              print('Page started loading: $url');
            },
            onPageFinished: (String url) {
              print('Page finished loading: $url');
            },
            gestureNavigationEnabled: true,
          );
        }));
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'VP App',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'VP App'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  vpmontag() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => VPMontag(
                'myurl')));
  }

  vpdienstag() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => VPDienstag(
                'myurl')));
  }

  vpmittwoch() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => VPMittwoch(
                'myurl')));
  }

  vpdonnerstag() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => VPDonnerstag(
                'myurl')));
  }

  vpfreitag() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => VPFreitag(
                'myurl')));
  }

  int _selectedIndex = 0;
  List<Widget> _widgetOptions = [];

  @override
  static TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  void initState() {
    _widgetOptions = <Widget>[
      Center(
        child: Container(
            child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceAround,
          children: <Widget>[
            Image.asset('images/uzw.jpg'),
          ],
        )),
      ),
      Center(
        child: Container(
          padding: EdgeInsets.all(8.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: <Widget>[
              RaisedButton(
                onPressed: vpmontag,
                child: Text('Montag'),
                padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
              ),
              RaisedButton(
                onPressed: vpdienstag,
                child: Text('Dienstag'),
                padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
              ),
              RaisedButton(
                onPressed: vpmittwoch,
                child: Text('Mittwoch'),
                padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
              ),
              RaisedButton(
                onPressed: vpdonnerstag,
                child: Text('Donnerstag'),
                padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
              ),
              RaisedButton(
                onPressed: vpfreitag,
                child: Text('Freitag'),
                padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
              )
            ],
          ),
        ),
      ),
      WebView(
        initialUrl:
            'myurl',
        javascriptMode: JavascriptMode.unrestricted,
      ),
      Text('Einstellungen')
    ];
    super.initState();
  }

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('VP App'),
      ),
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            title: Text('Startseite'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.view_headline),
            title: Text('Vertretungspläne'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.calendar_today),
            title: Text('Stundenpläne'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.settings),
            title: Text('Einstellungen'),
          ),
        ],
        showUnselectedLabels: true,
        currentIndex: _selectedIndex,
        unselectedItemColor: Colors.grey,
        selectedItemColor: Colors.blue[800],
        onTap: _onItemTapped,
      ),
    );
  }
}

希望您能帮助我。我不知道为什么它可以在模拟器上工作。

1 个答案:

答案 0 :(得分：0)

根据您的扑打医生显示的问题，可能是因为您不接受Android许可证。

您可以参考此帖子以接受它：https://stackoverflow.com/questions/48604914/flutter-run-error-you-have-not-accepted-the-license-agreements#:~:text=Execute%20command%20prompt%20as%20administrator,execute%20flutter%20doctor%20%2Dv%20again

主要步骤是：

  1. 以管理员身份执行命令提示符；
  2. 运行命令flutter doctor --android-licenses并接受所有许可证；
  3. 运行命令flutter doctor -v来检查问题是否已解决；
  4. 为确保一切正常，请以普通用户（您的用户）身份执行命令提示符，然后再次执行flutter doctor -v
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