Android 8.0以上系統應用如何保活

最近在作一個埋點的sdk，因爲埋點是分批上傳的，不是每次都上傳，因此會有個進程保活的機制，這也是自研推送的實現技術之一：如何保證Android進程的存活。

對於Android來講，保活主要有如下一些方法：

• 開啓前臺Service（效果好，推薦）
• Service中循環播放一段無聲音頻（效果較好，但耗電量高，謹慎使用）
• 雙進程守護（Android 5.0前有效）
• JobScheduler（Android 5.0後引入，8.0後失效）
• 1 像素activity保活方案（不推薦）
• 廣播鎖屏、自定義鎖屏（不推薦）
• 第三方推送SDK喚醒（效果好，缺點是第三方接入）

下面是具體的實現方案：

1.監聽鎖屏廣播，開啓1個像素的Activity

最先見到這種方案的時候是2015年，有個FM的app爲了向投資人展現月活，在Android應用中開啓一個1像素的Activity。

因爲Activity的級別是比較高的，因此開啓1個像素的Activity的方式就能夠保證進程是不容易被殺掉的。

具體來講，定義一個1像素的Activity，在該Activity中動態註冊自定義的廣播。

class OnePixelActivity : AppCompatActivity() {

    private lateinit var br: BroadcastReceiver

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        //設定一像素的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裏註冊廣播接受者    接受到廣播結束掉一像素
        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 {
            //銷燬的時候解鎖廣播
            unregisterReceiver(br)
        } catch (e: IllegalArgumentException) {
        }
        super.onDestroy()
    }

    /**
     * 檢查屏幕是否點亮
     */
    private fun checkScreenOn() {
        val pm = this@OnePixelActivity.getSystemService(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， 雙進程守護

雙進程守護，在Android 5.0前是有效的，5.0以後就不行了。首先，咱們定義定義一個本地服務，在該服務中播放無聲音樂，並綁定遠程服務

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 {
        //播放無聲音樂
        if (mediaPlayer == null) {
            mediaPlayer = MediaPlayer.create(this, R.raw.novioce)
            //聲音設置爲0
            mediaPlayer?.setVolume(0f, 0f)
            mediaPlayer?.isLooping = true//循環播放
            play()
        }
        //啓用前臺服務，提高優先級
        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)
        }
        //綁定守護進程
        try {
            val intent3 = Intent(this, RemoteService::class.java)
            this.bindService(intent3, connection, Context.BIND_ABOVE_CLIENT)
        } catch (e: Exception) {
        }

        //隱藏服務通知
        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()
        }
    }
}

而後再定義一個遠程服務，綁定本地服務。

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)
                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) {}
    }

}

/**
 * 通知欄點擊廣播接受者
 */
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從5.0增長的支持一種特殊的任務調度機制，能夠用它來實現進程保活，不過在Android8.0系統中，此種方法也失效。

首先，咱們定義一個JobService，開啓本地服務和遠程服務。

@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) //執行的最小延遲時間
                builder.setOverrideDeadline(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)  //執行的最長延時時間
                builder.setMinimumLatency(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)
                builder.setBackoffCriteria(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS, JobInfo.BACKOFF_POLICY_LINEAR)//線性重試方案
            } else {
                builder.setPeriodic(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS)
            }
            builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY)
            builder.setRequiresCharging(true) // 當插入充電器，執行該任務
            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)
            }
        }
        //啓動本地服務
        val localIntent = Intent(context, LocalService::class.java)
        //啓動守護進程
        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，提升Service優先級

在onStartCommand()方法中開啓一個通知，提升進程的優先級。注意：從Android 8.0（API級別26）開始，全部通知必需要分配一個渠道，對於每一個渠道，能夠單獨設置視覺和聽覺行爲。而後用戶能夠在設置中修改這些設置，根據應用程序來決定哪些通知能夠顯示或者隱藏。

首先，定義一個通知工具類，此工具欄兼容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 這個類型才能傳值
        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中的一個API，藉助Workmanager，咱們能夠用它來實現應用餓保活。使用前，咱們須要依賴Workmanager庫，以下：

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

Worker是一個抽象類，用來指定須要執行的具體任務。

public class KeepLiveWork extends Worker {
    private static final String TAG = "KeepLiveWork";

    @NonNull
    @Override
    public WorkerResult doWork() {
        Log.d(TAG, "keep-> doWork: startKeepService");
        //啓動job服務
        startJobService();
        //啓動相互綁定的服務
        startKeepService();
        return WorkerResult.SUCCESS;
    }
}

而後，啓動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);

    }

關於WorkManager，能夠經過下面的文章來詳細瞭解：WorkManager淺談