我有一个集成了 Flutter 模块的 android SDK。 Dart 代码是 Flutter 的基本增量示例。 我正在尝试将Dart代码加载到FlutterView中。我注意到虽然打印了Dart代码，但没有显示小部件
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffffff"
android:orientation="vertical">
<io.flutter.embedding.android.FlutterView
android:id="@+id/flutter_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
加载 dart 代码的代码(在 View.OnAttachStateChangeListener 中(：
override fun onViewAttachedToWindow(v: View?) {
v?.run {
FlutterMain.startInitialization(context)
FlutterMain.ensureInitializationComplete(context,null);
val flutterEngine = FlutterEngine(context)
flutterEngine.dartExecutor.executeDartEntrypoint(
// set which of dart methode will be used here
DartExecutor.DartEntrypoint(FlutterMain.findAppBundlePath(), "myMainDartMethod")
// to set here the main methode you can use this function to do this
// inteade of DartEntrypoint(FlutterMain.findAppBundlePath(),"myMainDartMethod")
// write this mdethode DartEntrypoint.createDefault()
//DartExecutor.DartEntrypoint.createDefault()
)
flutterView = findViewById(R.id.flutter_view)
flutterView.attachToFlutterEngine(flutterEngine)
}
}
我使用了"myMainDartMethod"和DartExecutor.DartEntrypoint.createDefault((都不起作用 飞镖代码：
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
@pragma('vm:entry-point') // say the release that this function must alos in the project used and it must not deleted
void myMainDartMethod() => runApp(MyApp()); // I use this function to show in the android activity
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
print("Flutter/MyApp in dart is called");
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or press Run > Flutter Hot Reload in a Flutter IDE). Notice that the
// counter didn't reset back to zero; the application is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also a layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
注意打印，它实际上是被调用的，但UI在Android端(FlutterView(中不可见。 我错过了什么？我可以添加/更改哪些内容来显示代码？
问题是我缺少生命周期通道状态。 我在 FlutterEngine 实例化后添加了以下行
val flutterEngine = FlutterEngine(context)
flutterEngine.lifecycleChannel.appIsResumed()
当然，您可能需要在正确的位置调用其他生命周期通道方法
来源： https://medium.com/@kassan424/sample-example-how-flutterview-in-a-android-activity-can-be-use-b9a887cd1d7