【发布时间】：2018-10-01 15:05:14
【问题描述】：
这可能是一个比较简单的问题，但是我是 Flutter 新手，今天需要实现一下。
我有一个看起来像这样的 Flutter 应用...
有一个 Flutter BottomNavigationBar 和一个 Flutter Webview_Plugin
我需要的只是在按下 Home 或 Language 按钮时加载一个新的 url。但我无法完全弄清楚 Flutter 范式。
我当前的代码，如果有帮助的话：
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';
import 'package:flutter_webview_plugin_example/home.dart';
import 'package:flutter_webview_plugin_example/settings.dart';
const kAndroidUserAgent =
'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Mobile Safari/537.36';
String selectedUrl = 'http://google.com';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'MyApp',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
routes: {
'/': (_) => const MyHomePage(title: 'MyApp'),
'/widget': (_) => new WebviewScaffold(
url: selectedUrl,
appBar: new AppBar(
title: const Text('Widget webview'),
),
withZoom: true,
withLocalStorage: true,
)
},
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
// Instance of WebView plugin
final flutterWebviewPlugin = new FlutterWebviewPlugin();
// On destroy stream
StreamSubscription _onDestroy;
// On urlChanged stream
StreamSubscription<String> _onUrlChanged;
// On urlChanged stream
StreamSubscription<WebViewStateChanged> _onStateChanged;
StreamSubscription<WebViewHttpError> _onHttpError;
StreamSubscription<double> _onScrollYChanged;
StreamSubscription<double> _onScrollXChanged;
final _urlCtrl = new TextEditingController(text: selectedUrl);
final _codeCtrl =
new TextEditingController(text: 'window.navigator.userAgent');
final _scaffoldKey = new GlobalKey<ScaffoldState>();
final _history = [];
@override
void initState() {
super.initState();
flutterWebviewPlugin.close();
SystemChrome.setEnabledSystemUIOverlays([SystemUiOverlay.bottom]);
_urlCtrl.addListener(() {
selectedUrl = _urlCtrl.text;
});
// Add a listener to on destroy WebView, so you can make came actions.
_onDestroy = flutterWebviewPlugin.onDestroy.listen((_) {
if (mounted) {
// Actions like show a info toast.
_scaffoldKey.currentState.showSnackBar(
const SnackBar(content: const Text('Webview Destroyed')));
}
});
// Add a listener to on url changed
_onUrlChanged = flutterWebviewPlugin.onUrlChanged.listen((String url) {
if (mounted) {
setState(() {
_history.add('onUrlChanged: $url');
});
}
});
_onScrollYChanged =
flutterWebviewPlugin.onScrollYChanged.listen((double y) {
if (mounted) {
setState(() {
_history.add("Scroll in Y Direction: $y");
});
}
});
_onScrollXChanged =
flutterWebviewPlugin.onScrollXChanged.listen((double x) {
if (mounted) {
setState(() {
_history.add("Scroll in X Direction: $x");
});
}
});
_onStateChanged =
flutterWebviewPlugin.onStateChanged.listen((WebViewStateChanged state) {
if (mounted) {
setState(() {
_history.add('onStateChanged: ${state.type} ${state.url}');
});
}
});
_onHttpError =
flutterWebviewPlugin.onHttpError.listen((WebViewHttpError error) {
if (mounted) {
setState(() {
_history.add('onHttpError: ${error.code} ${error.url}');
});
}
});
}
@override
void dispose() {
// Every listener should be canceled, the same should be done with this stream.
_onDestroy.cancel();
_onUrlChanged.cancel();
_onStateChanged.cancel();
_onHttpError.cancel();
_onScrollXChanged.cancel();
_onScrollYChanged.cancel();
flutterWebviewPlugin.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
BottomNavigationBar btm = new BottomNavigationBar(
items: [
new BottomNavigationBarItem(
icon: new Icon(
Icons.home,
color: const Color(0xFFFFFFFF),
),
title: new Text(
"Home",
style: new TextStyle(
color: const Color(0xFFFFFFFF),
),
)),
new BottomNavigationBarItem(
icon: new Icon(
Icons.settings,
color: const Color(0xFFFFFFFF),
),
title: new Text(
"Language",
style: new TextStyle(
color: const Color(0xFFFFFFFF),
),
)),
],
// onTap: changeURL()
);
flutterWebviewPlugin.launch(selectedUrl,
rect: new Rect.fromLTWH(
0.0, 0.0,
MediaQuery.of(context).size.width, MediaQuery.of(context).size.height - 55),
userAgent: kAndroidUserAgent);
return new Scaffold(
appBar: new AppBar(
title: new Text(
widget.title,
style: new TextStyle(color: const Color(0xFFFFFFFF)),
),
),
bottomNavigationBar: new Theme(
data: Theme.of(context).copyWith(
// sets the background color of the `BottomNavigationBar`
canvasColor: const Color(0xFF167F67),
), // sets the inactive color of the `BottomNavigationBar`
child: btm
),
);
}
}
【问题讨论】：