Node.js – How to make a plain text http (not https) request from Flutter

For testing purposes I would like to disable encryption so that I can connect my Flutter app to a server running on my localhost using http, not https. I've already been able to do it with https, but I get a crash for http because both Android and iOS do not allow plain text requests by default.

Here is my error:

E/flutter ( 9119): [ERROR:flutter/shell/common/shell.cc(186)] Dart Error: Unhandled exception:
E/flutter ( 9119): SocketException: OS Error: Connection refused, errno = 111, address = 10.0.2.2, port = 40738
E/flutter ( 9119): #0      IOClient.send (package:http/src/io_client.dart:33:23)
E/flutter ( 9119): <asynchronous suspension>
E/flutter ( 9119): #1      BaseClient._sendUnstreamed (package:http/src/base_client.dart:169:38)
E/flutter ( 9119): <asynchronous suspension>
E/flutter ( 9119): #2      BaseClient.get (package:http/src/base_client.dart:32:7)
E/flutter ( 9119): #3      get.<anonymous closure> (package:http/http.dart:46:36)
E/flutter ( 9119): #4      _withClient (package:http/http.dart:166:20)
E/flutter ( 9119): <asynchronous suspension>
E/flutter ( 9119): #5      get (package:http/http.dart:46:5)
E/flutter ( 9119): #6      _makeGetRequest (package:flutter_client/main.dart:64:29)
E/flutter ( 9119): <asynchronous suspension>
E/flutter ( 9119): #7      BodyWidgetState.build.<anonymous closure> (package:flutter_client/main.dart:48:19)
E/flutter ( 9119): #8      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
E/flutter ( 9119): #9      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
E/flutter ( 9119): #10     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter ( 9119): #11     TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter ( 9119): #12     TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
E/flutter ( 9119): #13     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
E/flutter ( 9119): #14     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
E/flutter ( 9119): #15     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
E/flutter ( 9119): #16     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:180:19)
E/flutter ( 9119): #17     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
E/flutter ( 9119): #18     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
E/flutter ( 9119): #19     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:101:7)
E/flutter ( 9119): #20     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:85:7)
E/flutter ( 9119): #21     _invoke1 (dart:ui/hooks.dart:173:13)
E/flutter ( 9119): #22     _dispatchPointerDataPacket (dart:ui/hooks.dart:127:5)

In Android I can disable encryption by adding a setting to the manifest:

android:usesCleartextTraffic="true"

In iOS I can do the same by adding a setting to Info.plist:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

But I don't know how to do that in Flutter.

Supplemental code

Flutter main.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Node server demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(title: Text('Flutter Client')),
        body: BodyWidget(),
      ),
    );
  }
}

class BodyWidget extends StatefulWidget {
  @override
  BodyWidgetState createState() {
    return new BodyWidgetState();
  }
}

class BodyWidgetState extends State<BodyWidget> {
  String serverResponse = 'Server response';

  @override
  Widget build(BuildContext context) {

    return Padding(
      padding: const EdgeInsets.all(32.0),
      child: Align(
        alignment: Alignment.topCenter,
        child: SizedBox(
          width: 200,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            children: <Widget>[
              RaisedButton(
                child: Text('Send request to server'),
                onPressed: () {
                  _makeGetRequest();
                },
              ),
              Padding(
                padding: const EdgeInsets.all(8.0),
                child: Text(serverResponse),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

_makeGetRequest() async {
  Response response = await get('http://10.0.2.2:3000');

  int statusCode = response.statusCode;
  Map<String, String> headers = response.headers;
  String contentType = headers['content-type'];
  String json = response.body;

  print(statusCode);
  print(headers);
  print(contentType);
  print(json);
}

Flutter pubspec.yaml

name: flutter_client
description: Flutter client to test Node.js server
version: 1.0.0+1

environment:
  sdk: ">=2.1.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  http: ^0.12.0+1

dev_dependencies:
  flutter_test:
    sdk: flutter

flutter:
  uses-material-design: true

Node.js app.js

const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

Testing with Android 9 emulator (API 28).

Update 1:

I tried adding android:usesCleartextTraffic="true" to the Android manifest in Flutter, but that didn't prevent the Dart error.

Update 2:

I was using https in my code rather than http. I updated that above and also changed to the new error message.

Update 3

Hmm, Flutter had an update (1.2.2) and I upgraded. Then I restarted Android Studio. And now it is working without any errors just with the code above. I don't know what was causing the exception. Could it be that Flutter doesn't require https?