Flutter使用android_alarm_manager_plus回调时触发assets_audio_player MissingPluginException

该报错核心源于android_alarm_manager_plus的回调函数运行在独立的Dart Isolate环境中，此环境未继承主Isolate的原生插件通道注册信息，因此调用assets_audio_player的原生交互方法时无法找到对应实现，触发MissingPluginException。

• 步骤1：在报警回调函数开头手动完成插件注册
  在回调函数内先初始化Flutter绑定，再调用自动生成的插件注册类，将所有原生插件注册到当前Isolate即可。
• 步骤2：补充Android端权限配置（针对Android 12及以上系统）
  在android/app/src/main/AndroidManifest.xml的manifest标签下添加精确闹钟权限：

  <uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM" />
  

• 步骤3：清理缓存重新构建
  依次执行以下命令清除历史构建缓存，再重新安装应用：

  flutter clean
  flutter pub get
  

import 'package:android_alarm_manager_plus/android_alarm_manager_plus.dart';
import 'package:assets_audio_player/assets_audio_player.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
// 导入自动生成的插件注册类，Flutter编译时自动生成无需手动创建
import 'generated_plugin_registrant.dart';

void printHello() async{
  // 新增：初始化当前Isolate的Flutter绑定
  WidgetsFlutterBinding.ensureInitialized();
  // 新增：注册所有原生插件到当前Isolate
  GeneratedPluginRegistrant.registerWith(WidgetsFlutterBinding.instance);

  final DateTime now = DateTime.now();
  print("[$now] Hello, world! function='$printHello'");

  ///play audio
  AssetsAudioPlayer assetsAudioPlayer =
  AssetsAudioPlayer.withId("App_ID");

  var audio = Audio(
    "assets/audios/music.mp3",
  );

  assetsAudioPlayer.open(audio,
      autoStart: true,
      showNotification: true,
  );
}


main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await AndroidAlarmManager.initialize();
  runApp(MyApp());
  await AndroidAlarmManager.oneShotAt(DateTime.now().add(Duration(seconds: 15)), 123456789, printHello);
}


class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Welcome to Flutter',
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Welcome to Flutter'),
        ),
        body: const Center(
          child: Text('Hello World'),
        ),
      ),
    );
  }
}

内容的提问来源于stack exchange，提问作者Sajjad