Flutter 应用音频播放器不播放 url src

Question

我正在学习一般的 Flutter 和移动开发，并且在我的第一个应用程序的开发中发现了一个问题。

应用本身只不过是一个资产播放器，它应该接收一个包含 url 的 var 并播放或停止音频流（它是本地广播），但资产根本不播放音频流。

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

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: MusicApp(),
    );
  }
}

class MusicApp extends StatefulWidget {
  @override
  _MusicAppState createState() => _MusicAppState();
}

class _MusicAppState extends State<MusicApp> {
  bool playing = false;
  IconData playBtn = Icons.play_arrow;
  String url = 'https://paineldj.com.br:7266/stream';

  AudioPlayer _player;

  @override
  void initState() {
    super.initState();
    _player = new AudioPlayer();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        width: double.infinity,
        decoration: BoxDecoration(
          image: DecorationImage(
            image: AssetImage("assets/bg.jpg"),
            fit: BoxFit.cover,
          ),
        ),
        child: Padding(
          padding: EdgeInsets.only(
            top: 48.0,
          ),
          child: Container(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.start,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [

                Center(
                  child: Container(
                    width: double.infinity,
                    height: 175.0,
                    decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(30.0),
                      image: DecorationImage(
                        image: AssetImage("assets/logo.jpg"),
                        fit: BoxFit.fill,
                      ),
                    ),
                  ),
                ),
                
                SizedBox(
                  height: 30.0,
                ),
                Expanded(
                  child: Container(
                    decoration: BoxDecoration(
                      color: Colors.black.withOpacity(0.5),
                      borderRadius: BorderRadius.only(
                        topLeft: Radius.circular(30.0),
                        topRight: Radius.circular(30.0),
                      ),
                    ),
                    child: Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      crossAxisAlignment: CrossAxisAlignment.center,
                      children: [
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          crossAxisAlignment: CrossAxisAlignment.center,
                          children: [
                            IconButton(
                              iconSize: 60.0,
                              color: Colors.deepPurple.shade300,
                              onPressed: () {
                                if (!playing) {
                                  _player.play(url);
                                  setState(() {
                                    playBtn = Icons.pause;
                                    playing = true;
                                  });
                                } else {
                                  _player.stop();
                                  setState(() {
                                    playBtn = Icons.play_arrow;
                                    playing = false;
                                  });
                                }
                              },
                              icon: Icon(playBtn),
                            ),
                          ],
                        ),
                      ],
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

据我所知，这个资产支持 url 来源，我的应用程序没有语法或执行错误。

我做错了什么？