Flutter - Android应用程序只显示一个空白屏幕

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flutter doctor

import 'package:flutter/material.dart';

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

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

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo Home Page'),
      ),
      body: Center(
        child: Text('Hello, World!'),
      ),
    );
  }
}

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.yourapp">

    <application
        android:label="yourapp"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|screenLayout|density|layoutDirection|fontScale|uiMode">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="androidación.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
</manifest>

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.2

flutter clean
flutter pub get
flutter build apk

flutter upgrade