我的应用程序为用户提供了在特定时间安排每日通知的选项。我AlarmManager用来实现这种行为。
单击一个按钮，我执行以下代码：
val datetimeToAlarm = Calendar.getInstance(Locale.getDefault())
/*datetimeToAlarm.set(HOUR_OF_DAY, 21)
datetimeToAlarm.set(MINUTE, 0)
datetimeToAlarm.set(SECOND, 0)
datetimeToAlarm.set(MILLISECOND, 0)*/
NotificationHelper.createNotificationChannel(
requireContext(),
NotificationManagerCompat.IMPORTANCE_DEFAULT,
false,
weather,
"Daily weather notifications for ${weather.cityName}"
)
NotificationHelper.scheduleNotification(
requireContext(),
datetimeToAlarm,
weather
)
出于测试目的，我还没有设置它必须触发的确切时间。
我上面使用的两种NotificationHelper类方法：
fun createNotificationChannel(
context: Context,
importance: Int,
showBadge: Boolean,
data: Weather,
description: String
) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
// Format: $placeId-$cityName
val channelId = "${data.placeId}-${data.cityName}"
val channel = NotificationChannel(channelId, "Weather for ${data.cityName}", importance)
channel.description = description
channel.setShowBadge(showBadge)
val notificationManager = context.getSystemService(NotificationManager::class.java)
notificationManager.createNotificationChannel(channel)
Log.v("Notifications", "Created channel $channelId")
}
}
fun scheduleNotification(context: Context, timeOfNotification: Calendar, data: Weather) {
val intent = Intent(context, AlarmReceiver::class.java)
intent.putExtra(EXTRA_TITLE, "Weather for ${data.cityName}")
intent.putExtra(EXTRA_TEXT, "Temperature: ${data.daily[0].temperature.min.roundToInt()}°/${data.daily[0].temperature.max.roundToInt()}°")
intent.putExtra(EXTRA_ID, data.id)
intent.putExtra(EXTRA_PLACE_ID, data.placeId)
intent.putExtra(EXTRA_CITY_NAME, data.cityName)
val pending =
PendingIntent.getBroadcast(context, data.id, intent, PendingIntent.FLAG_UPDATE_CURRENT)
// Schedule notification
val manager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
val repeatInterval: Long = 1000 * 60 * 15 // 15 minutes
manager.setRepeating(AlarmManager.RTC_WAKEUP, timeOfNotification.timeInMillis, repeatInterval, pending)
// start time is in AM/PM format
Log.v("Notifications", "Scheduled notification id ${data.id} with start at " +
"${SimpleDateFormat("yyyy-MM-dd hh:mm:ss", Locale.getDefault()).format(timeOfNotification.timeInMillis)} and interval " +
SimpleDateFormat("MM-dd hh:mm:ss", Locale.getDefault()).format(repeatInterval))
}
同样，出于测试目的，我将重复间隔设置为 15 分钟，以查看它是否有效。
在我BroadcastReciever的onReceive方法中，我只是打电话给createNotification我的NotificationHelper班级
override fun onReceive(context: Context, intent: Intent) {
// Deliver the notification.
Log.v("Notifications", "Receiver received call")
if (intent.extras == null) return
val title = intent.getStringExtra(NotificationHelper.EXTRA_TITLE)!!
val text = intent.getStringExtra(NotificationHelper.EXTRA_TEXT)!!
val id = intent.getIntExtra(NotificationHelper.EXTRA_ID, -1)
val placeId = intent.getStringExtra(NotificationHelper.EXTRA_PLACE_ID)
val cityName = intent.getStringExtra(NotificationHelper.EXTRA_CITY_NAME)
NotificationHelper.createNotification(
context,
title,
text,
"",
"$placeId-$cityName",
id
)
}
fun createNotification(
context: Context,
title: String,
message: String,
bigText: String,
channelId: String,
id: Int,
autoCancel: Boolean = true
) {
Log.v("Notifications", "Fired notification creation with following parameters: $title, $message, $channelId, $id")
val notificationBuilder = NotificationCompat.Builder(context, channelId).apply {
setSmallIcon(R.drawable.ic_launcher_foreground)
setContentTitle(title)
setContentText(message)
setStyle(NotificationCompat.BigTextStyle().bigText(bigText))
priority = NotificationCompat.PRIORITY_DEFAULT
setAutoCancel(autoCancel)
val intent = Intent(context, MainActivity::class.java)
intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
val pendingIntent = PendingIntent.getActivity(context, 0, intent, 0)
setContentIntent(pendingIntent)
}
val notificationManager = NotificationManagerCompat.from(context)
notificationManager.notify(id, notificationBuilder.build())
}
当然，我的接收器已在清单中注册：
<receiver
android:name=".utils.notifications.AlarmReceiver"
android:enabled="true"
android:exported="false"/>
当我在模拟器 API 30 上启动我的应用程序并单击按钮时，我得到以下日志：
2021-03-06 20:13:11.615 11229-11229/com.calamity.weather V/Notifications: Created channel location_place-Mountain View
2021-03-06 20:13:11.626 11229-11229/com.calamity.weather V/Notifications: Scheduled notification id 1 with start at 2021-03-06 08:13:11 and interval 01-01 03:15:00
2021-03-06 20:13:16.624 11229-11229/com.calamity.weather V/Notifications: Receiver received call
2021-03-06 20:13:16.624 11229-11229/com.calamity.weather V/Notifications: Fired notification creation with following parameters: Weather for Mountain View, Temperature: 9°/15°, location_place-Mountain View, 1
我的通知会立即显示，如果我关闭我的应用程序，它将在 15 分钟后再次发送。
但是，如果我在真实设备上启动它（小米红米 Note 9、MIUI Global 12.0.4、API 29），单击按钮我的日志是：
2021-03-06 20:16:50.945 19673-19673/com.calamity.weather V/Notifications: Created channel ChIJiQHsW0m3j4ARm69rRkrUF3w-Mountain View
2021-03-06 20:16:50.951 19673-19673/com.calamity.weather V/Notifications: Scheduled notification id 2 with start at 2021-03-06 08:16:50 and interval 01-01 03:15:00
如您所见，即使我的应用程序仍在前台，也不会触发警报，更不用说我是否将其从最近的应用程序列表中滑出。所以问题是：
- 为什么即使应用程序仍在运行它也不会触发？
- 我如何让它表现出应有的行为并在关闭应用程序的情况下传递我的通知？
我进行了研究，发现中文 ROM 积极限制服务和工作，但似乎AlarmManager无论如何都应该工作。