....
<application
        android:name="io.flutter.app.FlutterApplication"
        android:label="example"
        android:icon="@mipmap/ic_launcher"
        android:usesCleartextTraffic="true">
        ....
</application>
....

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

import 'package:flutter_radio/flutter_radio.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  static const streamUrl =
      "http://ia802708.us.archive.org/3/items/count_monte_cristo_0711_librivox/count_of_monte_cristo_001_dumas.mp3";

  bool isPlaying;

  @override
  void initState() {
    super.initState();
    audioStart();
    playingStatus();
  }

  Future<void> audioStart() async {
    await FlutterRadio.audioStart();
    print('Audio Start OK');
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('Audio Plugin Android'),
        ),
        body: new Center(
            child: Column(
          children: <Widget>[
            FlatButton(
              child: Icon(Icons.play_circle_filled),
              onPressed: () {
                FlutterRadio.playOrPause(url: streamUrl);
                playingStatus();
              },
            ),
            FlatButton(
              child: Icon(Icons.pause_circle_filled),
              onPressed: () {
                FlutterRadio.playOrPause(url: streamUrl);
                playingStatus();
              },
            ),
            FlatButton(
              child: Icon(Icons.stop),
              onPressed: () {
                FlutterRadio.playOrPause(url: streamUrl);
                playingStatus();
              },
            ),
            Text(
              'Check Playback Status: $isPlaying',
              style: TextStyle(fontSize: 25.0),
            )
          ],
        )),
      ),
    );
  }

  Future playingStatus() async {
    bool isP = await FlutterRadio.isPlaying();
    setState(() {
      isPlaying = isP;
    });
  }
}