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: BroadcastReceiver

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        //设定一像素的activity
        val window = window
        window.setGravity(Gravity.LEFT or Gravity.TOP)
        val params = window.attributes
        params.x = 0
        params.y = 0
        params.height = 1
        params.width = 1
        window.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 = [e-mail](Context.POWER_SERVICE) as PowerManager
        val 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? = null
    private var mBilder: MyBilder? = null

    override 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0
            mediaPlayer?.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_NOTIFICATION
            val 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)
            [e-mail](remoteService)
            val intent = Intent(this@LocalService, RemoteService::class.java)
            [e-mail](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? = null

    override 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_NOTIFICATION
                val notification = NotificationUtils.createNotification(this@RemoteService, title, discription, iconRes, intent)
                [e-mail](13691, notification)
            }
        }
    }

    private val connection = object : ServiceConnection {
        override fun onServiceDisconnected(name: ComponentName) {
            val remoteService = Intent(this@RemoteService,
                    LocalService::class.java)
            [e-mail](remoteService)
            [e-mail](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? = null

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        var startId = startId
        startService(this)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            mJobScheduler = getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobScheduler
            val 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_NOTIFICATION
                val 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 = false
        val activityManager = ctx
                .getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        val 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? = null
    private var id: String = context.packageName + "51"
    private var name: String = context.packageName
    private var context: Context = context
    private var channel: NotificationChannel? = null

    companion object {
        @SuppressLint("StaticFieldLeak")
        private var notificationUtils: NotificationUtils? = null

        fun createNotification(context: Context, title: String, content: String, icon: Int, intent: Intent): Notification? {
            if (notificationUtils == null) {
                notificationUtils = NotificationUtils(context)
            }
            var notification: Notification? = null
            notification = 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
    @Override
    public 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