Flutter应用完全关闭时如何显示本地通知（无需Firebase）

针对Android平台 #

WorkManager本身支持应用关闭后的任务执行，你遇到的问题可通过以下方式修复：

• 确保初始化时机正确：在Android原生MainApplication的onCreate方法中初始化WorkManager，而非仅在Flutter页面初始化，保证应用首次启动就完成任务注册：

  override fun onCreate() {
      super.onCreate()
      WorkManager.initialize(this, Configuration.Builder().build())
      // 此处可提前调度周期性任务
  }
  

• 规避系统后台限制：国产ROM（小米、华为等）存在严格的后台管控，需引导用户将应用加入后台白名单，可通过代码跳转至电池优化设置页：

  val intent = Intent(Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS)
  intent.data = Uri.parse("package:" + packageName)
  startActivity(intent)
  

• 正确配置周期性任务：设置persist: true保证设备重启后任务不丢失，同时遵循Android最短15分钟的周期限制：

  final periodicTask = PeriodicWorkRequest(
    myTask,
    repeatInterval: Duration(hours: 24),
    initialDelay: Duration(minutes: 1),
    constraints: Constraints(networkType: NetworkType.none),
  );
  await Workmanager().registerPeriodicTask(
    'daily_db_check',
    'dailyTask',
    existingWorkPolicy: ExistingWorkPolicy.replace,
    persist: true,
  );
  

针对iOS平台 #

iOS后台执行机制更严格，需依赖BGTaskScheduler配合WorkManager实现：

• 配置后台权限：在Xcode的Signing & Capabilities中添加Background Modes，勾选Background fetch和Background processing，或直接在Info.plist中添加UIBackgroundModes数组包含对应项。
• 原生侧注册任务：在AppDelegate中完成后台任务的注册与调度，确保应用启动时就完成配置：

  import UIKit
  import Flutter
  import workmanager
  import BackgroundTasks
  
  @UIApplicationMain
  @objc class AppDelegate: FlutterAppDelegate {
    override func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
      GeneratedPluginRegistrant.register(with: self)
      WorkmanagerPlugin.registerTask(withIdentifier: "dailyTask")
      BGTaskScheduler.shared.register(forTaskWithIdentifier: "dailyTask", using: nil) { task in
          self.handleBackgroundTask(task: task as! BGAppRefreshTask)
      }
      self.scheduleNextTask()
      return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
    
    func handleBackgroundTask(task: BGAppRefreshTask) {
        WorkmanagerPlugin.sharedPlugin?.executeTask(withIdentifier: "dailyTask", input: nil, completionHandler: { success in
            task.setTaskCompleted(success: success)
        })
        self.scheduleNextTask()
    }
    
    func scheduleNextTask() {
        let request = BGAppRefreshTaskRequest(identifier: "dailyTask")
        request.earliestBeginDate = Date(timeIntervalSinceNow: 24*60*60)
        do {
            try BGTaskScheduler.shared.submit(request)
        } catch {
            print("调度任务失败: \(error)")
        }
    }
  }
  

• 注意iOS限制：iOS无法保证任务精确执行，系统会根据设备电量、使用场景调度，应用完全关闭后仅在系统允许后台唤醒时触发任务。

跨平台通用要点 #

• 数据库路径正确性：后台任务中访问sqflite时，使用绝对路径初始化数据库，避免上下文差异导致的路径错误：

  final dbPath = await getDatabasesPath();
  final database = await openDatabase(join(dbPath, 'your_db.db'));
  

• 通知权限与渠道配置：Android 8.0+需提前创建通知渠道，iOS需主动请求通知权限，确保后台能正常展示通知：

  if (Platform.isAndroid) {
    const AndroidNotificationChannel channel = AndroidNotificationChannel(
      'daily_alert_channel',
      '每日提醒',
      description: '数据库检查结果通知',
      importance: Importance.high,
    );
    final FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    await flutterLocalNotificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()?.createNotificationChannel(channel);
  }
  

内容的提问来源于stack exchange，提问作者Matteo Preda