Flutter Websockets MacOS：相同的代码可以在调试模式下工作，但不能在发布模式下工作：“（操作系统错误：提供了节点名或服务名..）”

Summary

我有一个在 Flutter 中使用 WebSockets 的程序，该程序在debug模式，但运行相同exact代码在release模式会导致错误。

Context

Flutter 文档告诉我们如何使用 WebSocket https://docs.flutter.dev/cookbook/networking/web-sockets.

让我们考虑使用official使用 WebSockets 的代码示例（我对其进行了一些修改以在Text小部件）：

import 'package:flutter/material.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    const title = 'WebSocket Demo';
    return const MaterialApp(
      title: title,
      home: MyHomePage(
        title: title,
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({
    super.key,
    required this.title,
  });

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final TextEditingController _controller = TextEditingController();
  final _channel = WebSocketChannel.connect(
    Uri.parse('wss://echo.websocket.events'),
  );

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Form(
              child: TextFormField(
                controller: _controller,
                decoration: const InputDecoration(labelText: 'Send a message'),
              ),
            ),
            const SizedBox(height: 24),
            StreamBuilder(
              stream: _channel.stream,
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  return Text(snapshot.data.toString());
                } else if (snapshot.hasError) {
                  return Text(snapshot.error.toString());
                } else {
                  return const Text('listening...');
                }
              },
            )
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _sendMessage,
        tooltip: 'Send message',
        child: const Icon(Icons.send),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

  void _sendMessage() {
    if (_controller.text.isNotEmpty) {
      _channel.sink.add(_controller.text);
    }
  }

  @override
  void dispose() {
    _channel.sink.close();
    _controller.dispose();
    super.dispose();
  }
}

问题

如果您在 MacOS 上以调试模式运行上述代码片段，它将正常工作。但是，如果您使用以下方式构建应用程序flutter build macos，你会得到这个错误：

SocketException: Failed host lookup: ‘...’ (OS Error: nodename nor servname provided, or not known, errno = 8)

我尝试过的

1. SocketException: Connection failed (OS Error: Operation not permitted, errno = 1) with flutter app on macOS https://stackoverflow.com/questions/65458903/socketexception-connection-failed-os-error-operation-not-permitted-errno-1?rq=1 which said to add this <key>com.apple.security.network.client</key> <true/>

2. SocketException: Failed host lookup: ‘...com’ (OS Error: nodename nor servname provided, or not known, errno = 8) https://stackoverflow.com/questions/66063913/socketexception-failed-host-lookup-com-os-error-nodename-nor-servname-p

3. ssh: Could not resolve hostname [hostname]: nodename nor servname provided, or not known https://stackoverflow.com/questions/20252294/ssh-could-not-resolve-hostname-hostname-nodename-nor-servname-provided-or-n

4. 关闭我的防火墙。

5. 确保有有效的互联网连接。

Question

为什么上面的代码片段在 Debug 模式下可以工作，但在运行时却不能在 Release 模式下工作flutter build macos?

Note

Running

flutter doctor -v

说“没有发现问题”。

您说它适用于调试模式，但不适用于发布模式，所以我怀疑您已经将权利添加到调试配置文件中，但您可能忘记将其添加到发布配置文件中。

Under macos > Runner目录中，找到“DebugProfile.entitlements”和“Release.entitlements”文件：

将此部分添加到两个文件中：

<key>com.apple.security.network.client</key>
<true/>