服务未按预期方式唤醒设备 [英] Service is not waking up device as it should

问题描述

我的应用程序每秒执行一次重复请求-向服务器询问新数据，如果有，则唤醒设备并运行主应用程序. (这是根据用户的请求，他们不关心电池使用情况，必须每秒运行一次.这是非常关键的操作) (用户允许对设置进行的任何更改都可以帮助您)

My application do a repeating request each second - asking the server for a new data, and if there is such - it wakes up the device and run the main application. ( this is by the request from the users, and they does not care about the battery usage, it is mandatory to run each second. It is Highly Critical Operation ) ( any changes to the settings which could help is allowed by the user )

我正在尝试通过使用AlarmManager或System.Threading.Timer(两者都尝试过)来实现这一目标，但是每次我最终遇到以下问题时:

I am curently trying to achieve this by using either AlarmManager or System.Threading.Timer ( tried with both ), but each time I am ending up with the follow issue :

• 设备在休眠状态下的某个时间点停止请求服务器，并且在某个看起来随机的时间恢复了它的短暂工作.为什么会发生这种情况，以及如何解决此问题?

(操作系统:Android 5.x)

( OS : Android 5.x )

来自Java服务变体的代码(使用AlarmManager)

The code from the variation of the service in Java ( using AlarmManager )

Calendar cal = Calendar.getInstance();
        cal.add( Calendar.SECOND, ConfigReader.serviceRepeatInterval );

        Intent intent = new Intent( this, SaleService.class );

        PendingIntent pintent = PendingIntent.getService( this, 0, intent, 0 );

        AlarmManager alarm = ( AlarmManager )getSystemService( Context.ALARM_SERVICE );

        alarm.setRepeating( AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), ConfigReader.serviceRepeatInterval, pintent );

该服务的变种形式的代码是使用Timer的C#(Xamarin).

The code from the variation of the service is C# ( Xamarin ) using Timer.

public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {

            if( _powerManager == null )
            {
                 _powerManager = (PowerManager)this.GetSystemService(PowerService);
                _wakeLock      = _powerManager.NewWakeLock( WakeLockFlags.Full | WakeLockFlags.AcquireCausesWakeup | WakeLockFlags.OnAfterRelease, mySaleServiceWakeLock );
                 vibrator      = (Vibrator)this.GetSystemService( Context.VibratorService );                
            }

            timer = new System.Threading.Timer( getCurrentPendingObjects, null, timerRepeatInterval, Timeout.Infinite );

            return StartCommandResult.Sticky;
        }

推荐答案

警报触发时，使用AlarmManager.ELAPSED_REALTIME_WAKEUP或AlarmManager.RTC_WAKEUP可以唤醒设备.

Using AlarmManager.ELAPSED_REALTIME_WAKEUP or AlarmManager.RTC_WAKEUP will wake the device up when the alarm fires.

设备在休眠状态下的某个时候停止请求服务器 并在一些看起来像随机的时间恢复了它的短暂工作. 为什么会发生这种情况，以及如何解决此问题?

The device stop requesting the server at some point while it is slept and at some look-like random time it restore it's work for a short. Why this happens, and how to fix this issue?

这可能是因为您的PendingIntent正在呼叫Service.这样，设备可以在执行onStartCommand()之前返回睡眠状态. 您应该改用BroadcastReceiver(因为在onReceive()中保证"了WakeLock)，在onReceive()中获取了WakeLock，从此处启动Service，并从<释放了WakeLock c5>(在适当的时候).

This might happen because your PendingIntent is calling a Service. This way the device can go back to sleep before onStartCommand() gets executed. You should use a BroadcastReceiver instead (since a WakeLock is "guaranteed" during onReceive()), aquire a WakeLock in onReceive(), start your Service from there and release your WakeLock from the Service, when appropriate.

尽管如此，每隔一秒钟重复一次请求(甚至在设备处于睡眠状态时)似乎是一个糟糕的设计.它将很快耗尽电池电量.

Although, repeating a request every second for an extended period of time (and even when the device is in sleep) seems like a terrible design. It will drain the battery pretty fast.

您应该重新考虑实现，可以改用某种回调机制，或者至少(显着)增加请求之间的间隔.

You should rethink your implementation, maybe use some sort of a callback mechanism instead, or at least increase the intervals between the requests (significantly).

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