Android 8.0以上系统应用如何保活

最近在做一个埋点的sdk，由于埋点是分批上传的，不是每次都上传，所以会有个进程保活的机制，这也是自研推送的实现技术之一：如何保证Android进程的存活。

对于Android来说，保活主要有以下一些方法：

开启前台Service（效果好，推荐）
Service中循环播放一段无声音频（效果较好，但耗电量高，谨慎使用）
双进程守护（Android 5.0前有效）
JobScheduler（Android 5.0后引入，8.0后失效）
1 像素activity保活方案（不推荐）
广播锁屏、自定义锁屏（不推荐）
第三方推送SDK唤醒（效果好，缺点是第三方接入）

下面是具体的实现方案：

1.监听锁屏广播，开启1个像素的Activity

最早见到这种方案的时候是2015年，有个FM的app为了向投资人展示月活，在Android应用中开启一个1像素的Activity。

由于Activity的级别是比较高的，所以开启1个像素的Activity的方式就可以保证进程是不容易被杀掉的。

具体来说，定义一个1像素的Activity，在该Activity中动态注册自定义的广播。

class OnePixelActivity : AppCompatActivity() {private lateinit var br: BroadcastReceiveroverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)//设定一像素的activityval window = windowwindow.setGravity(Gravity.LEFT or Gravity.TOP)val params = window.attributesparams.x = 0params.y = 0params.height = 1params.width = 1window.attributes = params//在一像素activity里注册广播接受者    接受到广播结束掉一像素br = object : BroadcastReceiver() {override fun onReceive(context: Context, intent: Intent) {finish()}}registerReceiver(br, IntentFilter("finish activity"))checkScreenOn()}override fun onResume() {super.onResume()checkScreenOn()}override fun onDestroy() {try {//销毁的时候解锁广播unregisterReceiver(br)} catch (e: IllegalArgumentException) {}super.onDestroy()}/*** 检查屏幕是否点亮*/private fun checkScreenOn() {val pm = this@OnePixelActivity.getSystemService(Context.POWER_SERVICE) as PowerManagerval isScreenOn = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT_WATCH) {pm.isInteractive} else {pm.isScreenOn}if (isScreenOn) {finish()}}
}

2，双进程守护

双进程守护，在Android 5.0前是有效的，5.0之后就不行了。首先，我们定义定义一个本地服务，在该服务中播放无声音乐，并绑定远程服务

class LocalService : Service() {private var mediaPlayer: MediaPlayer? = nullprivate var mBilder: MyBilder? = nulloverride fun onCreate() {super.onCreate()if (mBilder == null) {mBilder = MyBilder()}}override fun onBind(intent: Intent): IBinder? {return mBilder}override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {//播放无声音乐if (mediaPlayer == null) {mediaPlayer = MediaPlayer.create(this, R.raw.novioce)//声音设置为0mediaPlayer?.setVolume(0f, 0f)mediaPlayer?.isLooping = true//循环播放play()}//启用前台服务，提升优先级if (KeepLive.foregroundNotification != null) {val intent2 = Intent(applicationContext, NotificationClickReceiver::class.java)intent2.action = NotificationClickReceiver.CLICK_NOTIFICATIONval notification = NotificationUtils.createNotification(this, KeepLive.foregroundNotification!!.getTitle(), KeepLive.foregroundNotification!!.getDescription(), KeepLive.foregroundNotification!!.getIconRes(), intent2)startForeground(13691, notification)}//绑定守护进程try {val intent3 = Intent(this, RemoteService::class.java)this.bindService(intent3, connection, Context.BIND_ABOVE_CLIENT)} catch (e: Exception) {}//隐藏服务通知try {if (Build.VERSION.SDK_INT < 25) {startService(Intent(this, HideForegroundService::class.java))}} catch (e: Exception) {}if (KeepLive.keepLiveService != null) {KeepLive.keepLiveService!!.onWorking()}return Service.START_STICKY}private fun play() {if (mediaPlayer != null &amp;&amp; !mediaPlayer!!.isPlaying) {mediaPlayer?.start()}}private inner class MyBilder : GuardAidl.Stub() {@Throws(RemoteException::class)override fun wakeUp(title: String, discription: String, iconRes: Int) {}}private val connection = object : ServiceConnection {override fun onServiceDisconnected(name: ComponentName) {val remoteService = Intent(this@LocalService,RemoteService::class.java)this@LocalService.startService(remoteService)val intent = Intent(this@LocalService, RemoteService::class.java)this@LocalService.bindService(intent, this,Context.BIND_ABOVE_CLIENT)}override fun onServiceConnected(name: ComponentName, service: IBinder) {try {if (mBilder != null &amp;&amp; KeepLive.foregroundNotification != null) {val guardAidl = GuardAidl.Stub.asInterface(service)guardAidl.wakeUp(KeepLive.foregroundNotification?.getTitle(), KeepLive.foregroundNotification?.getDescription(), KeepLive.foregroundNotification!!.getIconRes())}} catch (e: RemoteException) {e.printStackTrace()}}}override fun onDestroy() {super.onDestroy()unbindService(connection)if (KeepLive.keepLiveService != null) {KeepLive.keepLiveService?.onStop()}}
}

然后再定义一个远程服务，绑定本地服务。

class RemoteService : Service() {private var mBilder: MyBilder? = nulloverride fun onCreate() {super.onCreate()if (mBilder == null) {mBilder = MyBilder()}}override fun onBind(intent: Intent): IBinder? {return mBilder}override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {try {this.bindService(Intent(this@RemoteService, LocalService::class.java),connection, Context.BIND_ABOVE_CLIENT)} catch (e: Exception) {}return Service.START_STICKY}override fun onDestroy() {super.onDestroy()unbindService(connection)}private inner class MyBilder : GuardAidl.Stub() {@Throws(RemoteException::class)override fun wakeUp(title: String, discription: String, iconRes: Int) {if (Build.VERSION.SDK_INT < 25) {val intent = Intent(applicationContext, NotificationClickReceiver::class.java)intent.action = NotificationClickReceiver.CLICK_NOTIFICATIONval notification = NotificationUtils.createNotification(this@RemoteService, title, discription, iconRes, intent)this@RemoteService.startForeground(13691, notification)}}}private val connection = object : ServiceConnection {override fun onServiceDisconnected(name: ComponentName) {val remoteService = Intent(this@RemoteService,LocalService::class.java)this@RemoteService.startService(remoteService)this@RemoteService.bindService(Intent(this@RemoteService,LocalService::class.java), this, Context.BIND_ABOVE_CLIENT)}override fun onServiceConnected(name: ComponentName, service: IBinder) {}}}/*** 通知栏点击广播接受者*/
class NotificationClickReceiver : BroadcastReceiver() {companion object {const val CLICK_NOTIFICATION = "CLICK_NOTIFICATION"}override fun onReceive(context: Context, intent: Intent) {if (intent.action == NotificationClickReceiver.CLICK_NOTIFICATION) {if (KeepLive.foregroundNotification != null) {if (KeepLive.foregroundNotification!!.getForegroundNotificationClickListener() != null) {KeepLive.foregroundNotification!!.getForegroundNotificationClickListener()?.foregroundNotificationClick(context, intent)}}}}
}

3，JobScheduler

JobScheduler是Android从5.0增加的支持一种特殊的任务调度机制，可以用它来实现进程保活，不过在Android8.0系统中，此种方法也失效。

首先，我们定义一个JobService，开启本地服务和远程服务。

@SuppressWarnings(value = ["unchecked", "deprecation"])
@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
class JobHandlerService : JobService() {private var mJobScheduler: JobScheduler? = nulloverride fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {var startId = startIdstartService(this)if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {mJobScheduler = getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobSchedulerval builder = JobInfo.Builder(startId++,ComponentName(packageName, JobHandlerService::class.java.name))if (Build.VERSION.SDK_INT >= 24) {builder.setMinimumLatency(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS) //执行的最小延迟时间builder.setOverrideDeadline(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)  //执行的最长延时时间builder.setMinimumLatency(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)builder.setBackoffCriteria(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS, JobInfo.BACKOFF_POLICY_LINEAR)//线性重试方案} else {builder.setPeriodic(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)}builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY)builder.setRequiresCharging(true) // 当插入充电器，执行该任务mJobScheduler?.schedule(builder.build())}return Service.START_STICKY}private fun startService(context: Context) {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {if (KeepLive.foregroundNotification != null) {val intent = Intent(applicationContext, NotificationClickReceiver::class.java)intent.action = NotificationClickReceiver.CLICK_NOTIFICATIONval notification = NotificationUtils.createNotification(this, KeepLive.foregroundNotification!!.getTitle(), KeepLive.foregroundNotification!!.getDescription(), KeepLive.foregroundNotification!!.getIconRes(), intent)startForeground(13691, notification)}}//启动本地服务val localIntent = Intent(context, LocalService::class.java)//启动守护进程val guardIntent = Intent(context, RemoteService::class.java)startService(localIntent)startService(guardIntent)}override fun onStartJob(jobParameters: JobParameters): Boolean {if (!isServiceRunning(applicationContext, "com.xiyang51.keeplive.service.LocalService") || !isServiceRunning(applicationContext, "$packageName:remote")) {startService(this)}return false}override fun onStopJob(jobParameters: JobParameters): Boolean {if (!isServiceRunning(applicationContext, "com.xiyang51.keeplive.service.LocalService") || !isServiceRunning(applicationContext, "$packageName:remote")) {startService(this)}return false}private fun isServiceRunning(ctx: Context, className: String): Boolean {var isRunning = falseval activityManager = ctx.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManagerval servicesList = activityManager.getRunningServices(Integer.MAX_VALUE)val l = servicesList.iterator()while (l.hasNext()) {val si = l.next()if (className == si.service.className) {isRunning = true}}return isRunning}
}

4，提高Service优先级

在onStartCommand()方法中开启一个通知，提高进程的优先级。注意：从Android 8.0（API级别26）开始，所有通知必须要分配一个渠道，对于每个渠道，可以单独设置视觉和听觉行为。然后用户可以在设置中修改这些设置，根据应用程序来决定哪些通知可以显示或者隐藏。

首先，定义一个通知工具类，此工具栏兼容Android 8.0。

class NotificationUtils(context: Context) : ContextWrapper(context) {private var manager: NotificationManager? = nullprivate var id: String = context.packageName + "51"private var name: String = context.packageNameprivate var context: Context = contextprivate var channel: NotificationChannel? = nullcompanion object {@SuppressLint("StaticFieldLeak")private var notificationUtils: NotificationUtils? = nullfun createNotification(context: Context, title: String, content: String, icon: Int, intent: Intent): Notification? {if (notificationUtils == null) {notificationUtils = NotificationUtils(context)}var notification: Notification? = nullnotification = if (Build.VERSION.SDK_INT >= 26) {notificationUtils?.createNotificationChannel()notificationUtils?.getChannelNotification(title, content, icon, intent)?.build()} else {notificationUtils?.getNotification_25(title, content, icon, intent)?.build()}return notification}}@RequiresApi(api = Build.VERSION_CODES.O)fun createNotificationChannel() {if (channel == null) {channel = NotificationChannel(id, name, NotificationManager.IMPORTANCE_MIN)channel?.enableLights(false)channel?.enableVibration(false)channel?.vibrationPattern = longArrayOf(0)channel?.setSound(null, null)getManager().createNotificationChannel(channel)}}private fun getManager(): NotificationManager {if (manager == null) {manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager}return manager!!}@RequiresApi(api = Build.VERSION_CODES.O)fun getChannelNotification(title: String, content: String, icon: Int, intent: Intent): Notification.Builder {//PendingIntent.FLAG_UPDATE_CURRENT 这个类型才能传值val pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)return Notification.Builder(context, id).setContentTitle(title).setContentText(content).setSmallIcon(icon).setAutoCancel(true).setContentIntent(pendingIntent)}fun getNotification_25(title: String, content: String, icon: Int, intent: Intent): NotificationCompat.Builder {val pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)return NotificationCompat.Builder(context, id).setContentTitle(title).setContentText(content).setSmallIcon(icon).setAutoCancel(true).setVibrate(longArrayOf(0)).setSound(null).setLights(0, 0, 0).setContentIntent(pendingIntent)}
}

5，Workmanager方式

Workmanager是Android JetPac中的一个API，借助Workmanager，我们可以用它来实现应用饿保活。使用前，我们需要依赖Workmanager库，如下：

implementation "android.arch.work:work-runtime:1.0.0-alpha06"

Worker是一个抽象类，用来指定需要执行的具体任务。

public class KeepLiveWork extends Worker {private static final String TAG = "KeepLiveWork";@NonNull@Overridepublic WorkerResult doWork() {Log.d(TAG, "keep-> doWork: startKeepService");//启动job服务startJobService();//启动相互绑定的服务startKeepService();return WorkerResult.SUCCESS;}
}

然后，启动keepWork方法，

    public void startKeepWork() {WorkManager.getInstance().cancelAllWorkByTag(TAG_KEEP_WORK);Log.d(TAG, "keep-> dowork startKeepWork");OneTimeWorkRequest oneTimeWorkRequest = new OneTimeWorkRequest.Builder(KeepLiveWork.class).setBackoffCriteria(BackoffPolicy.LINEAR, 5, TimeUnit.SECONDS).addTag(TAG_KEEP_WORK).build();WorkManager.getInstance().enqueue(oneTimeWorkRequest);}

关于WorkManager，可以通过下面的文章来详细了解：WorkManager浅谈