如何在Android（Kotlin）中用Alarm Manager设置空闲时重复闹钟

核心实现思路 #

由于Android 6.0+的Doze模式限制，常规重复闹钟方法（如setInexactRepeating）在设备空闲时会被系统推迟。要实现空闲状态下的可靠重复闹钟，需采用单次精确闹钟+触发后重置的方案，结合setExactAndAllowWhileIdle（API 23+）确保Doze模式下也能触发。

完整实现步骤 #

1. 定义广播接收器

闹钟触发后通过广播接收器处理通知展示，并重置下一次闹钟：

class ReminderNotificationReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        context ?: return
        intent ?: return

        // 展示通知
        val title = intent.getStringExtra(notificationTitleExtra) ?: "提醒"
        val message = intent.getStringExtra(notificationMessageExtra) ?: "您有一条提醒"
        
        val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(
                "REMINDER_CHANNEL",
                "提醒通知",
                NotificationManager.IMPORTANCE_DEFAULT
            )
            notificationManager.createNotificationChannel(channel)
        }
        
        val notification = NotificationCompat.Builder(context, "REMINDER_CHANNEL")
            .setContentTitle(title)
            .setContentText(message)
            .setSmallIcon(R.drawable.ic_notification) // 替换为你的通知图标
            .build()
        
        notificationManager.notify(REMINDER_NOTIFICATION_ID, notification)

        // 重置下一次重复闹钟
        setNextRepeatAlarm(context, title, message)
    }

    private fun setNextRepeatAlarm(context: Context, title: String, message: String) {
        val intent = Intent(context, ReminderNotificationReceiver::class.java)
        intent.putExtra(notificationTitleExtra, title)
        intent.putExtra(notificationMessageExtra, message)

        val pendingIntent = PendingIntent.getBroadcast(
            context,
            REMINDER_NOTIFICATION_ID,
            intent,
            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
        )

        val alarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
        // 计算下一次触发时间（示例为间隔1年）
        val nextTriggerTime = Calendar.getInstance().apply {
            timeInMillis = System.currentTimeMillis()
            add(Calendar.YEAR, 1)
        }.timeInMillis

        // 根据系统版本选择合适的闹钟设置方法
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            alarmManager.setExactAndAllowWhileIdle(
                AlarmManager.RTC_WAKEUP,
                nextTriggerTime,
                pendingIntent
            )
        } else {
            alarmManager.setExact(
                AlarmManager.RTC_WAKEUP,
                nextTriggerTime,
                pendingIntent
            )
        }
    }

    companion object {
        const val notificationTitleExtra = "notification_title"
        const val notificationMessageExtra = "notification_message"
        const val REMINDER_NOTIFICATION_ID = 1001
    }
}

2. 初始设置闹钟（Activity中调用）

在需要启动闹钟的地方调用此方法，设置首次触发时间：

fun setupInitialRepeatAlarm(activity: Activity, notificationTitle: String, notificationMessage: String) {
    val billName = activity.binding.etBillName.text.toString().trim()
    val message = "$notificationMessage $billName"
    
    val intent = Intent(activity, ReminderNotificationReceiver::class.java)
    intent.putExtra(ReminderNotificationReceiver.notificationTitleExtra, notificationTitle)
    intent.putExtra(ReminderNotificationReceiver.notificationMessageExtra, message)

    val pendingIntent = PendingIntent.getBroadcast(
        activity,
        ReminderNotificationReceiver.REMINDER_NOTIFICATION_ID,
        intent,
        PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
    )

    val alarmManager = activity.getSystemService(Context.ALARM_SERVICE) as AlarmManager
    // 设置首次触发时间（示例为立即触发，可根据需求调整）
    val firstTriggerTime = System.currentTimeMillis()

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        alarmManager.setExactAndAllowWhileIdle(
            AlarmManager.RTC_WAKEUP,
            firstTriggerTime,
            pendingIntent
        )
    } else {
        alarmManager.setExact(
            AlarmManager.RTC_WAKEUP,
            firstTriggerTime,
            pendingIntent
        )
    }
}

3. 清单文件注册广播接收器

在AndroidManifest.xml中添加接收器注册：

<receiver
    android:name=".ReminderNotificationReceiver"
    android:exported="false"/>

关键细节说明 #

• 闹钟类型选择：AlarmManager.RTC_WAKEUP会在触发时唤醒设备，确保通知及时展示；若无需唤醒设备，可改用AlarmManager.RTC。
• PendingIntent Flag：FLAG_IMMUTABLE是API 30+的推荐设置，避免PendingIntent被篡改；FLAG_UPDATE_CURRENT用于更新已存在的PendingIntent的Extra数据。
• Doze模式适配：setExactAndAllowWhileIdle是唯一能在Doze模式下触发的闹钟方法，但仅支持单次设置，因此必须在广播接收器中重置下一次闹钟以实现重复效果。
• 通知渠道：Android 8.0+必须创建通知渠道，否则通知无法正常显示。

内容的提问来源于stack exchange，提问作者Femi