android - 重新打开应用程序后，创建了一个服务的多个实例

Question

我正在尝试创建一个应用程序来更新持久通知，即使在应用程序关闭时也是如此。现在，我正在使用在 MainActivity 的 onCreate() 中启动的服务:

serviceIntent = Intent(this, PersistentService::class.java)
val stopped = stopService(serviceIntent)
println("[123] stopped: $stopped")
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    startForegroundService(serviceIntent)
} else {
    startService(serviceIntent)
}

这非常适合启动它。但是，当我重新打开并关闭应用程序时，即使打印了 stopped: true ，但之前的服务仍在运行并且没有调用之前服务的 stopService()。

PersistentService 类的简化版本:

var timesStarted = 0
var lastService: PersistentService? = null

class PersistentService: Service(){
    private var timer: Timer? = null
    private var task: AsyncTask<*, *, *>? = null

    override fun onBind(intent: Intent?): IBinder? {
        return null
    }

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        timesStarted++
        println("[123]starting persistent service. timesStarted: $timesStarted lastService===this: ${lastService===this} lastService==this: ${lastService==this} lastService: $lastService")
        println("[123] hashCode: ${hashCode()}")
        lastService = this
        if(timer == null){
            timer = Timer()
        }
        setToLoadingNotification()
        timer?.scheduleAtFixedRate(object : TimerTask(){
            override fun run(){
                println("[123]Updating hashCode: ${this@PersistentService.hashCode()}")
                if(task?.status == AsyncTask.Status.RUNNING){
                    // send notification saying last request timed out
                }
                task?.cancel(true)

                task = DataUpdaterTask(DatabaseDataRequester { GlobalData.connectionProperties }) { dataRequest ->
                    // send notification based on dataRequest value
                }.execute()
            }
        }, 1000L, UPDATE_PERIOD)
        return START_STICKY
    }

    private fun notify(notification: Notification){
        getManager().notify(NOTIFICATION_ID, notification)
        startForeground(NOTIFICATION_ID, notification)
    }
    private fun getBuilder(): Notification.Builder {
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
            return Notification.Builder(this, NotificationChannels.PERSISTENT_STATUS.id)
        }
        return Notification.Builder(this)
    }
    private fun getManager() = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

    override fun stopService(name: Intent?): Boolean {
        println("[123]Stopping persistent service")
        timer?.cancel() // stop the timer from calling the code any more times
        task?.cancel(true) // stop the code from running if it's running
//        getManager().cancel(NOTIFICATION_ID)
        return super.stopService(name)
    }
}

这是输出

[123] stopped: false
[123]starting persistent service. timesStarted: 1 lastService===this: false lastService==this: false lastService: null
[123] hashCode: 4008007
[123]Updating hashCode: 4008007
[123]Got successful data request
[123]Updating hashCode: 4008007
[123]Got successful data request
// *close and reopen the app*
[123] stopped: true
[123]starting persistent service. timesStarted: 2 lastService===this: false lastService==this: false lastService: me.retrodaredevil.solarthing.android.PersistentService@3d2847
[123] hashCode: 7823272
[123]Updating hashCode: 7823272
[123]Got successful data request
[123]Updating hashCode: 4008007
[123]Got successful data request
[123]Updating hashCode: 7823272
[123]Got successful data request

从输出中可以看出，两个服务同时运行。哈希码显示它们不是同一个对象，所以如果我将我的代码放在 onCreate() 而不是 onStartCommand() 中并不重要(我已经测试过了)

如果有人能指出我正确的方向，那将会很有帮助。我是 android 开发的新手，我很难找到正确的方法来做到这一点。我什至不确定我现在正在做的是否是更新通知的最佳方式。

Answer 1

and the previous service's stopService() was not called.

stopService() 不是 Service 的生命周期方法。也许您正在考虑 onDestroy()。

the previous service is still running

不是，之前的服务实例被停止了。你刚刚泄露了 Timer，因为你没有在 onDestroy() 中取消 Timer。

因此，重写 onDestroy()，将你的 cancel() 调用放在那里，摆脱 stopService() 的其余部分，而且你应该处于更好的状态。