[英]Why is LocationCallback not firing within CallbackToFutureAdapter?
What I need to accomplish: My application should request the current location of the user, repeating every 15 minutes, also in the background and even when the application is terminated.我需要完成的工作:我的应用程序应该请求用户的当前位置,每 15 分钟重复一次,在后台甚至在应用程序终止时也是如此。
What I did: I am using the FusedLocationProviderAPI, called within a periodical WorkManager, extending the ListenableWorker, as the API is asynchronous.我所做的:我正在使用 FusedLocationProviderAPI,在定期 WorkManager 中调用,扩展 ListenableWorker,因为 API 是异步的。 Each time a new Location Update is provided by the system (max. every fifteen minutes), a LocationCallback is called.
每次系统提供新的位置更新时(最多每十五分钟一次),就会调用 LocationCallback。
As ResolvableFuture seems to be deprecated to use within the ListenableWorker's startWork-Method, I use the CallbackToFutureAdapter.由于 ResolvableFuture 似乎不推荐在 ListenableWorker 的 startWork-Method 中使用,我使用 CallbackToFutureAdapter。 Within this adapter, I initialize the LocationCallback and call the doWork-Method, which includes all the logic for requesting information.
在这个适配器中,我初始化 LocationCallback 并调用 doWork-Method,其中包括请求信息的所有逻辑。
My problem: When the screen is active, everything works fine .我的问题:当屏幕处于活动状态时,一切正常。 But as soon as the application runs in the background or is terminated, the LocationCallback won't be evoked.
但是一旦应用程序在后台运行或终止,就不会调用 LocationCallback。 (last log: "Waiting for callback").
(最后的日志:“等待回调”)。 Please note that I removed big chunks of code below (like exception handling and details).
请注意,我删除了下面的大块代码(如异常处理和详细信息)。
Here's my code within the MyWorker extends ListenableWorker startWork-Method:这是我在 MyWorker 扩展 ListenableWorker startWork-Method 中的代码:
public ListenableFuture<Result> startWork() {
return CallbackToFutureAdapter.getFuture(completer -> {
mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
super.onLocationResult(locationResult);
// Storing data to different repositories.
completer.set(Result.success());
}
};
doWork();
return "startSomeAsyncStuff";
});
}
doWork():做工作():
public Result doWork() {
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(mContext);
mSettingsClient = LocationServices.getSettingsClient(mContext);
createLocationCallback();
createLocationRequest();
buildLocationSettingsRequest();
startLocationUpdates();
return Result.success();
}
startLocationUpdates():开始位置更新():
private void startLocationUpdates() {
// Begin by checking if the device has the necessary location settings.
mSettingsClient.checkLocationSettings(mLocationSettingsRequest)
.addOnSuccessListener(new OnSuccessListener<LocationSettingsResponse>() {
@Override
public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
Log.i(TAG, "All location settings are satisfied.");
mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.getMainLooper());
Log.i(TAG, "Location updated requested - Waiting for Callback");
}
})
Related posts: How do I return a ListenableFuture<Result> with work manager 2.0?相关文章: 如何使用工作管理器 2.0 返回 ListenableFuture<Result>? and WorkManager: ResolvableFuture can only be called from within the same library group prefix
和WorkManager: ResolvableFuture 只能从同一个库组前缀中调用
So, after hours of trial and error here's the solution that finally works for me:因此,经过数小时的反复试验,这是最终对我有用的解决方案:
The trick is to add a Foreground-Service, that ensures the worker not to be cancelled, until a new Location-Update arrives from the system.诀窍是添加一个前台服务,以确保工作人员不会被取消,直到系统有新的位置更新到达。 However, you can not avoid showing a Notification during that timeframe.
但是,您无法避免在该时间范围内显示通知。 I also moved the LocationCallback into the doWork-Method, just before requesting Location Updates (as you need to pass the Callback to that method.)
在请求位置更新之前,我还将 LocationCallback 移到了 doWork 方法中(因为您需要将回调传递给该方法。)
This solution is based on https://developer.android.com/topic/libraries/architecture/workmanager/advanced/long-running , which I should have taken a look at in the beginning to save me some frustration;)该解决方案基于https://developer.android.com/topic/libraries/architecture/workmanager/advanced/long-running ,我应该在一开始就看一下,以免让我感到沮丧;)
Here's the startWork()-Method:这是 startWork() 方法:
public ListenableFuture<Result> startWork() {
return CallbackToFutureAdapter.getFuture(completer -> {
setForegroundAsync(createForegroundInfo());
doWork(completer);
// This value is used only for debug purposes: it will be used
// in toString() of returned future or error cases.
return "Location Worker";
});
}
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