按下设备后退按钮时出现 Flutter WebView 异常
Flutter WebView exception on device back button pressed
我是 Flutter 的新手,所以如果这是一个基本问题,请原谅我。
我正在尝试创建一个仅显示全屏网络视图的 Flutter 应用程序,但我需要设备后退按钮才能返回历史记录。第一个任务我轻松完成,第二个任务我很挣扎。
我按照此 中的说明进行操作,但我无法删除 360 多行仅对后退按钮的答复的所有混乱并使其正常工作。
我的代码真的很简单:
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
void main() => runApp(MyApp());
WebViewController _controller;
Future<void> _onWillPop(BuildContext context) async {
if (await _controller.canGoBack()) {
_controller.goBack();
} else {
exit(0);
return Future.value(false);
}
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
SystemChrome.setEnabledSystemUIOverlays([]);
return WillPopScope(
onWillPop: () => _onWillPop(context),
child: MaterialApp(title: 'Test App', home: WebView(
initialUrl: 'https://google.com',
javascriptMode: JavascriptMode.unrestricted,
onWebViewCreated: (WebViewController c) => _controller = c,
)),
);
}
}
但是当我尝试按下设备后退按钮时,它抛出以下错误:
java.lang.RuntimeException: Cannot execute operation because FlutterJNI is not attached to native.
at io.flutter.embedding.engine.FlutterJNI.ensureAttachedToNative(FlutterJNI.java:227)
at io.flutter.embedding.engine.FlutterJNI.markTextureFrameAvailable(FlutterJNI.java:554)
at io.flutter.embedding.engine.renderer.FlutterRenderer.markTextureFrameAvailable(FlutterRenderer.java:274)
at io.flutter.embedding.engine.renderer.FlutterRenderer.access0(FlutterRenderer.java:38)
at io.flutter.embedding.engine.renderer.FlutterRenderer$SurfaceTextureRegistryEntry.onFrameAvailable(FlutterRenderer.java:145)
at android.graphics.SurfaceTexture.handleMessage(SurfaceTexture.java:211)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7520)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
flutter 的 github 上至少有 3 个线程,但 none 的解决方案对我有用。我在这里错过了什么?
您可以复制粘贴 运行 下面的完整代码
您可以使用 Completer
代码片段
WebViewController controller;
final Completer<WebViewController> _controllerCompleter =
Completer<WebViewController>();
...
onWebViewCreated: (WebViewController c) {
_controllerCompleter.future.then((value) => controller = value);
_controllerCompleter.complete(c);
},
工作演示
完整代码
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'dart:async';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
WebViewController controller;
final Completer<WebViewController> _controllerCompleter =
Completer<WebViewController>();
Future<void> _onWillPop(BuildContext context) async {
print("onwillpop");
if (await controller.canGoBack()) {
controller.goBack();
} else {
exit(0);
return Future.value(false);
}
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () => _onWillPop(context),
child: Scaffold(
body: WebView(
initialUrl: 'https://flutter.dev/',
javascriptMode: JavascriptMode.unrestricted,
onWebViewCreated: (WebViewController c) {
_controllerCompleter.future.then((value) => controller = value);
_controllerCompleter.complete(c);
},
),
),
);
}
}
在AndroidMainActivity.kt中,只需添加:
override fun onDestroy() { flutterEngine?.platformViewsController?.onFlutterViewDestroyed() super.onDestroy() }
这是有效的解决方案(100% 有效)-
// Use any webview plugin
// WebView _controller;
Future<void> _handleBack(context) async {
var status = await _controller.canGoBack();
if (status) {
_controller.goBack();
} else {
showDialog(
context: context,
builder: (context) => AlertDialog(
title: Text('Do you want to exit'),
actions: <Widget>[
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('No'),
),
FlatButton(
onPressed: () {
SystemNavigator.pop();
},
child: Text('Yes'),
),
],
));
}
}
这里调用WillPopScope
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () => _handleBack(context),
child: SafeArea(
top: true,
child: Scaffold(......)))
我是 Flutter 的新手,所以如果这是一个基本问题,请原谅我。
我正在尝试创建一个仅显示全屏网络视图的 Flutter 应用程序,但我需要设备后退按钮才能返回历史记录。第一个任务我轻松完成,第二个任务我很挣扎。
我按照此
我的代码真的很简单:
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
void main() => runApp(MyApp());
WebViewController _controller;
Future<void> _onWillPop(BuildContext context) async {
if (await _controller.canGoBack()) {
_controller.goBack();
} else {
exit(0);
return Future.value(false);
}
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
SystemChrome.setEnabledSystemUIOverlays([]);
return WillPopScope(
onWillPop: () => _onWillPop(context),
child: MaterialApp(title: 'Test App', home: WebView(
initialUrl: 'https://google.com',
javascriptMode: JavascriptMode.unrestricted,
onWebViewCreated: (WebViewController c) => _controller = c,
)),
);
}
}
但是当我尝试按下设备后退按钮时,它抛出以下错误:
java.lang.RuntimeException: Cannot execute operation because FlutterJNI is not attached to native.
at io.flutter.embedding.engine.FlutterJNI.ensureAttachedToNative(FlutterJNI.java:227)
at io.flutter.embedding.engine.FlutterJNI.markTextureFrameAvailable(FlutterJNI.java:554)
at io.flutter.embedding.engine.renderer.FlutterRenderer.markTextureFrameAvailable(FlutterRenderer.java:274)
at io.flutter.embedding.engine.renderer.FlutterRenderer.access0(FlutterRenderer.java:38)
at io.flutter.embedding.engine.renderer.FlutterRenderer$SurfaceTextureRegistryEntry.onFrameAvailable(FlutterRenderer.java:145)
at android.graphics.SurfaceTexture.handleMessage(SurfaceTexture.java:211)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7520)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
flutter 的 github 上至少有 3 个线程,但 none 的解决方案对我有用。我在这里错过了什么?
您可以复制粘贴 运行 下面的完整代码
您可以使用 Completer
代码片段
WebViewController controller;
final Completer<WebViewController> _controllerCompleter =
Completer<WebViewController>();
...
onWebViewCreated: (WebViewController c) {
_controllerCompleter.future.then((value) => controller = value);
_controllerCompleter.complete(c);
},
工作演示
完整代码
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'dart:async';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
WebViewController controller;
final Completer<WebViewController> _controllerCompleter =
Completer<WebViewController>();
Future<void> _onWillPop(BuildContext context) async {
print("onwillpop");
if (await controller.canGoBack()) {
controller.goBack();
} else {
exit(0);
return Future.value(false);
}
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () => _onWillPop(context),
child: Scaffold(
body: WebView(
initialUrl: 'https://flutter.dev/',
javascriptMode: JavascriptMode.unrestricted,
onWebViewCreated: (WebViewController c) {
_controllerCompleter.future.then((value) => controller = value);
_controllerCompleter.complete(c);
},
),
),
);
}
}
在AndroidMainActivity.kt中,只需添加:
override fun onDestroy() { flutterEngine?.platformViewsController?.onFlutterViewDestroyed() super.onDestroy() }
这是有效的解决方案(100% 有效)-
// Use any webview plugin
// WebView _controller;
Future<void> _handleBack(context) async {
var status = await _controller.canGoBack();
if (status) {
_controller.goBack();
} else {
showDialog(
context: context,
builder: (context) => AlertDialog(
title: Text('Do you want to exit'),
actions: <Widget>[
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('No'),
),
FlatButton(
onPressed: () {
SystemNavigator.pop();
},
child: Text('Yes'),
),
],
));
}
}
这里调用WillPopScope
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () => _handleBack(context),
child: SafeArea(
top: true,
child: Scaffold(......)))