Android 警报管理器不适用于 Flutter Project App

Question

我已经在我的新 Flutter 应用中安装了 Android Alarm Manager 插件。我尝试使用插件的示例代码，但它在控制台中出现错误。

请建议如何使 Android 警报管理器插件工作。如何将 Dart 的 android_alarm_manager 集成到应用程序中，以便用户在他们在时间表中选择的时间到达时收到警报？

我使用此链接中的代码: https://github.com/flutter/plugins/tree/master/packages/android_alarm_manager

main.dart:

import 'dart:isolate';
import 'package:android_alarm_manager/android_alarm_manager.dart';
import 'package:flutter/material.dart';
    
void printHello() {
  final DateTime now = DateTime.now();
  final int isolateId = Isolate.current.hashCode;
  print("[$now] Hello, world! isolate=${isolateId} function='$printHello'");
}

void main() async {
  final int helloAlarmID = 0;
  await AndroidAlarmManager.initialize();
  runApp(MaterialApp(home: Application()));
  await AndroidAlarmManager.periodic(const Duration(minutes: 1), helloAlarmID, printHello);
}

class Application extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(),
    );
  }
}

Application.java:

package io.flutter.plugins.androidalarmmanagerexample;
import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
    
public class Application extends FlutterApplication implements PluginRegistrantCallback {
    @Override
    public void onCreate() {
        super.onCreate();
    
        AlarmService.setPluginRegistrant(this);
    }

    @Override
    public void registerWith(PluginRegistry registry) {
        GeneratedPluginRegistrant.registerWith(registry);
    }
}               

当我运行此代码时，它会向控制台打印以下错误:

E/flutter ( 6831): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(error, Attempt to invoke interface method 'void io.flutter.plugin.common.PluginRegistry$PluginRegistrantCallback.registerWith(io.flutter.plugin.common.PluginRegistry)' on a null object reference, null)
E/flutter ( 6831): #0      JSONMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:149:7)
E/flutter ( 6831): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:302:33)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #2      AndroidAlarmManager.initialize (package:android_alarm_manager/android_alarm_manager.dart:76:10)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #3      main (package:alarmdemo/main.dart:12:29)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #4      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:189:25)
E/flutter ( 6831): #5      _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 6831): #6      _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 6831): #7      _runZoned (dart:async/zone.dart:1516:10)
E/flutter ( 6831): #8      runZoned (dart:async/zone.dart:1500:12)
E/flutter ( 6831): #9      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:180:5)
E/flutter ( 6831): #10     _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:300:19)
E/flutter ( 6831): #11     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
E/flutter ( 6831): 
E/flutter ( 6831): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: MissingPluginException(No implementation found for method AlarmService.initialized on channel plugins.flutter.io/android_alarm_manager_background)
E/flutter ( 6831): #0      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:300:7)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #1      _alarmManagerCallbackDispatcher (package:android_alarm_manager/android_alarm_manager.dart:49:12)
E/flutter ( 6831): #2      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:189:25)
E/flutter ( 6831): #3      _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 6831): #4      _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 6831): #5      _runZoned (dart:async/zone.dart:1516:10)
E/flutter ( 6831): #6      runZoned (dart:async/zone.dart:1500:12)
E/flutter ( 6831): #7      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:180:5)
E/flutter ( 6831): #8      _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:300:19)
E/flutter ( 6831): #9      _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
E/flutter ( 6831): 

这是我更新的代码:

main.dart:

void printHello() {
  final DateTime now = new DateTime.now();
  final int isolateId = Isolate.current.hashCode;
  print("[$now] Hello, world! isolate=${isolateId} 
      function='$printHello'");
}

void main() async {
  runApp(MaterialApp(home: Application()));
}
    
class Application extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: Center(
          child: RaisedButton(
            child: Text('Hello'),
            onPressed: () {
              runAlarm();
            },
          ),
        ),
      ),
    );
  }

  void runAlarm() {
    AndroidAlarmManager.oneShot(
      Duration(seconds: 10),
      0,
      printHello,
      wakeup: true,
    ).then((val) => print(val));
  }

  static void alarmTest() {
    print("test");
  }
}

它不会向控制台打印任何错误，但会打印以下两行:

E/AlarmService(11943): Fatal: failed to find callback
I/AlarmService(11943): AlarmService has not yet started.

我也尝试初始化警报管理器，但它会向控制台打印错误:

void runAlarm() {
  AndroidAlarmManager.periodic(
    Duration(seconds: 10),
    0,
    printHello,
    wakeup: true,
  ).then((val) => print(val)).catchError((e) {
    print(e);
  });
}

错误:

E/flutter ( 6831): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(error, Attempt to invoke interface method 'void io.flutter.plugin.common.PluginRegistry$PluginRegistrantCallback.registerWith(io.flutter.plugin.common.PluginRegistry)' on a null object reference, null)
E/flutter ( 6831): #0      JSONMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:149:7)
E/flutter ( 6831): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:302:33)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #2      AndroidAlarmManager.initialize (package:android_alarm_manager/android_alarm_manager.dart:76:10)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #3      main (package:alarmdemo/main.dart:12:29)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #4      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:189:25)
E/flutter ( 6831): #5      _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 6831): #6      _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 6831): #7      _runZoned (dart:async/zone.dart:1516:10)
E/flutter ( 6831): #8      runZoned (dart:async/zone.dart:1500:12)
E/flutter ( 6831): #9      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:180:5)
E/flutter ( 6831): #10     _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:300:19)
E/flutter ( 6831): #11     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
E/flutter ( 6831): 
E/flutter ( 6831): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: MissingPluginException(No implementation found for method AlarmService.initialized on channel plugins.flutter.io/android_alarm_manager_background)
E/flutter ( 6831): #0      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:300:7)
E/flutter ( 6831): <asynchronous suspension>
E/flutter ( 6831): #1      _alarmManagerCallbackDispatcher (package:android_alarm_manager/android_alarm_manager.dart:49:12)
E/flutter ( 6831): #2      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:189:25)
E/flutter ( 6831): #3      _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 6831): #4      _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 6831): #5      _runZoned (dart:async/zone.dart:1516:10)
E/flutter ( 6831): #6      runZoned (dart:async/zone.dart:1500:12)
E/flutter ( 6831): #7      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:180:5)
E/flutter ( 6831): #8      _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:300:19)
E/flutter ( 6831): #9      _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
E/flutter ( 6831): 

Answer 1

在挣扎了几个小时后，我终于自己解决了这个问题(但感觉时间更长了!)。当我真正克隆了 Flutter Plugins Github repository 时，突破就来了。包含 android_alarm_manager并浏览了示例代码并查看了它在 IDE 中的布局，而不是在线查看孤立的文件。

如果您不精通 Android Java 开发，自述文件不太清楚具体要做什么，但是当您查看工作示例代码时就会清楚。

您需要加入 Application.java将它们在示例目录中提供给您的文件放入您的实际项目中，与您现有的 MainActivity.java 位于同一文件夹中文件。内容应如下所示:

package io.flutter.plugins.androidalarmmanagerexample;

import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import io.flutter.plugins.androidalarmmanager.AlarmService;

public class Application extends FlutterApplication implements PluginRegistrantCallback {
  @Override
  public void onCreate() {
    super.onCreate();
    AlarmService.setPluginRegistrant(this);
  }

  @Override
  public void registerWith(PluginRegistry registry) {
    GeneratedPluginRegistrant.registerWith(registry);
  }
}

至于你需要把这个文件放在哪里，他们的例子看起来像这样，但你的可能是 <your project dir>/android/app/src/main/java/com/example/<your project name> :

完成此操作后，您必须更新 Application.java 第一行的包名称来自 package io.flutter.plugins.androidalarmmanagerexample;匹配您的项目使用的任何包(请参阅现有 MainActivity.java 的第一行)。如果你不这样做，gradle 就找不到它并且没有任何效果!

您现在可以按照 Readme 中的建议进行操作了，添加权限等:

After importing this plugin to your project as usual, add the following to your AndroidManifest.xml within the <manifest></manifest> tags:

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

Next, within the <application></application> tags, add:

<service
    android:name="io.flutter.plugins.androidalarmmanager.AlarmService"
    android:permission="android.permission.BIND_JOB_SERVICE"
    android:exported="false"/>
<receiver
    android:name="io.flutter.plugins.androidalarmmanager.AlarmBroadcastReceiver"
    android:exported="false"/>
<receiver
    android:name="io.flutter.plugins.androidalarmmanager.RebootBroadcastReceiver"
    android:enabled="false">
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED"></action>
    </intent-filter>
</receiver>

最后一部分是最让我困惑的部分。听起来他们很模糊，但如果你之前做的一切都完全正确，那实际上正是你需要做的。

Which must be reflected in the application's AndroidManifest.xml. E.g.:

    <application
        android:name=".Application"
        ...

只需更改您的android:name至.Application ，这意味着它现在将使用 Application.java我们之前添加的。

就是这样!希望您现在可以运行您的应用程序。