我目前正在服用 Udemy (https://www.udemy.com/course/learn-flutter-dart-to-build-ios-android-apps/) Flutter 课程，在学习期间，我已经能够完成大部分设置。 我的（默认）演示代码可以编译并显示 Web 应用程序 https://ibb.co/GRzPdQx 但无法显示 我在 VS code 和 Android Studio 中的物理设备和模拟器。
每当我编译它时，它都会显示以下错误：
Exception in thread "main" java.net.SocketException: A connection attempt failed because the connected party did not properly respond after some time, or established connection failed because the connected host has failed to respond
at java.base/sun.nio.ch.NioSocketImpl.implRead(NioSocketImpl.java:325)
at java.base/sun.nio.ch.NioSocketImpl.read(NioSocketImpl.java:350)
at java.base/sun.nio.ch.NioSocketImpl$1.read(NioSocketImpl.java:803)
at java.base/java.net.Socket$SocketInputStream.read(Socket.java:966)
at java.base/sun.security.ssl.SSLSocketInputRecord.read(SSLSocketInputRecord.java:484)
at java.base/sun.security.ssl.SSLSocketInputRecord.readHeader(SSLSocketInputRecord.java:478)
at java.base/sun.security.ssl.SSLSocketInputRecord.decode(SSLSocketInputRecord.java:160)
at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:111)
at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1510)
at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1425)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:455)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:426)
at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:580)
at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:187)
at java.base/sun.net.www.protocol.http.HttpURLConnection.followRedirect0(HttpURLConnection.java:2902)
at java.base/sun.net.www.protocol.http.HttpURLConnection.followRedirect(HttpURLConnection.java:2811)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1927)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1589)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:224)
at org.gradle.wrapper.Download.downloadInternal(Download.java:58)
at org.gradle.wrapper.Download.download(Download.java:44)
at org.gradle.wrapper.Install$1.call(Install.java:61)
at org.gradle.wrapper.Install$1.call(Install.java:48)
at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
at org.gradle.wrapper.Install.createDist(Install.java:48)
at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
Exception: Gradle task assembleDebug failed with exit code 1
Exited (sigterm)
我尝试安装 JDK，并按照 Stackoverflow 上提供的几个步骤进行操作，例如 如何解决 Execution failed for task ':app:compileFlutterBuildDebug'，我还做了一些 github 建议，例如 flutter --v、flutter clean、flutter run 但它们对我不起作用。 每当我尝试在 Android 上选择模拟器时，我也会收到以下建议 工作室：
打开模拟器时出错信息 | Android模拟器版本32.1.15.0 (build_id 10696886) (CL:N/A) 信息 |找到系统路径 C:\Android\sdk\system-images ndroid-34\google_apis\x86_64\ 警告 | 请将模拟器更新为支持以下功能的模拟器： 支持PixelFold 错误|使用相同的 AVD 运行多个模拟器 错误|是一个实验性功能。错误|请使用-只读标志 启用此功能。信息|将崩溃数据存储在： C:\Users\user\AppData\Local\Temp\AndroidEmulator mu-crash.db， 检测已启用重复的日志行将被删除，如果您 希望看到每个单独的行都带有 -log-nofilter 标志启动。 信息|找到 IPv4 服务器：192.168.172.68
同时，我的模拟器正在使用 Pixel 6 运行最新的 Android 版本 (Api 34)。
顺便说一下main.dart代码：
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter - The Complete Guide',
theme: ThemeData(
// This is the theme of your application.
//
// TRY THIS: Try running your application with "flutter run". You'll see
// the application has a blue toolbar. Then, without quitting the app,
// try changing the seedColor in the colorScheme below to Colors.green
// and then invoke "hot reload" (save your changes or press the "hot
// reload" button in a Flutter-supported IDE, or press "r" if you used
// the command line to start the app).
//
// Notice that the counter didn't reset back to zero; the application
// state is not lost during the reload. To reset the state, use hot
// restart instead.
//
// This works for code too, not just values: Most code changes can be
// tested with just a hot reload.
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
useMaterial3: true,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
// 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
State<MyHomePage> 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(
// TRY THIS: Try changing the color here to a specific color (to
// Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
// change color while the other colors stay the same.
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
// 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.
//
// 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).
//
// TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
// action in the IDE, or press "p" in the console), to see the
// wireframe for each widget.
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headlineMedium,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
如果有人能提供解决方案，我将不胜感激。
对于 Android 设备，
首先，您应该在物理设备中启用开发者选项
然后将您的设备连接到您的计算机，此时您将在物理设备上看到一些弹出窗口，您应该允许您的计算机访问USB调试。
3.现在您可以在物理设备上运行您的应用程序。