应用程序关闭时 Android 服务停止

我从我主要的 Android 活动中启动了一项服务，如下所示:

final Context context = base.getApplicationContext();
final Intent intent = new Intent(context, MyService.class);
startService(intent);

当我从最近的应用程序列表中滑出活动页面关闭它时，服务会停止运行并在一段时间后重新启动。由于我的应用程序需求，我不能将持久化服务与通知一起使用。我怎样才能使服务不重新启动或关闭，只是继续运行在应用程序退出？

119509 次浏览
小开

This may help you. I may be mistaken but it seems to me that this is related with returning START_STICKY in your onStartCommand() method. You can avoid the service from being called again by returning START_NOT_STICKY instead.

小开
最佳答案

I'm in the same situation, so far I learned when the app is closed the service get closed also because they are in a one thread, so the service should be on another thread in order fot it not to be closed, look into that and look into keeping the service alive with alarm manager here an example http://www.vogella.com/articles/AndroidServices/article.html this way your service won't be shown in notification.

lastly, after all the research I've done I'm coming to realize that the best choice for a long running service is startForeground(), because it is made for that and the system actually deals with your service well.

小开

try this, it will keep the service running in the background.

BackServices.class

public class BackServices extends Service{


@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}


@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// Let it continue running until it is stopped.
Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
return START_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
}
}

in your MainActivity onCreate drop this line of code 

startService(new Intent(getBaseContext(), BackServices.class));

Now the service will stay running in background.

小开

Why not use an IntentService?

IntentService opens a new Thread apart from the main Thread and works there, that way closing the app wont effect it

Be advised that IntentService runs the onHandleIntent() and when its done the service closes, see if it fits your needs. http://developer.android.com/reference/android/app/IntentService.html

小开

Just override onDestroy method in your first visible activity like after splash you have home page and while redirecting from splash to home page you have already finish splash. so put on destroy in home page. and stop service in that method.

小开

make you service like this in your Mainifest 

 <service
android:name=".sys.service.youservice"
android:exported="true"
android:process=":ServiceProcess" />

then your service will run on other process named ServiceProcess

if you want make your service never die :

  1. onStartCommand() return START_STICKY

  2. onDestroy() -> startself

  3. create a Deamon service

  4. jin -> create a Native Deamon process, you can find some open-source projects on github

  5. startForeground() , there is a way to startForeground without Notification ,google it

小开

The Main problem is in unable to start the service when app closed, android OS(In Some OS) will kill the service for Resource Optimization, If you are not able to restart the service then call a alarm manger to start the receiver like this,Here is the entire code, This code will keep alive ur service.

Manifest is,

         <service
android:name=".BackgroundService"
android:description="@string/app_name"
android:enabled="true"
android:label="Notification" />
<receiver android:name="AlarmReceiver">
<intent-filter>
<action android:name="REFRESH_THIS" />
</intent-filter>
</receiver>

IN Main Activty start alarm manger in this way,

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


Intent intent = new Intent("REFRESH_THIS");
PendingIntent pi = PendingIntent.getBroadcast(this, 123456789, intent, 0);


int type = AlarmManager.RTC_WAKEUP;
long interval = 1000 * 50;


am.setInexactRepeating(type, System.currentTimeMillis(), interval, pi);

this will call reciver and reciver is,

public class AlarmReceiver extends BroadcastReceiver {
Context context;


@Override
public void onReceive(Context context, Intent intent) {
this.context = context;


System.out.println("Alarma Reciver Called");


if (isMyServiceRunning(this.context, BackgroundService.class)) {
System.out.println("alredy running no need to start again");
} else {
Intent background = new Intent(context, BackgroundService.class);
context.startService(background);
}
}


public static boolean isMyServiceRunning(Context context, Class<?> serviceClass) {
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);


if (services != null) {
for (int i = 0; i < services.size(); i++) {
if ((serviceClass.getName()).equals(services.get(i).service.getClassName()) && services.get(i).pid != 0) {
return true;
}
}
}
return false;
}
}

And this Alaram reciver calls once when android app is opened and when app is closed.SO the service is like this,

public class BackgroundService extends Service {
private String LOG_TAG = null;


@Override
public void onCreate() {
super.onCreate();
LOG_TAG = "app_name";
Log.i(LOG_TAG, "service created");
}


@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i(LOG_TAG, "In onStartCommand");
//ur actual code
return START_STICKY;
}


@Override
public IBinder onBind(Intent intent) {
// Wont be called as service is not bound
Log.i(LOG_TAG, "In onBind");
return null;
}


@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
@Override
public void onTaskRemoved(Intent rootIntent) {
super.onTaskRemoved(rootIntent);
Log.i(LOG_TAG, "In onTaskRemoved");
}


@Override
public void onDestroy() {
super.onDestroy();
Log.i(LOG_TAG, "In onDestroyed");
}
}
小开

Best solution is to use the sync Adapter in android to start the service. Create a Sync Adapter and call start service their.. inside onPerformSync method. to create sync Account please refer this link https://developer.android.com/training/sync-adapters/index.html

Why SyncAdapter? Ans: Because earlier you used to start the service using your App context. so whenever your app process get killed (When u remove it from task manager or OS kill it because of lack of resources ) at that time your service will also be removed. SyncAdapter will not work in application thread.. so if u call inside it.. service will no longer be removed.. unless u write code to remove it.

小开 
<service android:name=".Service2"
android:process="@string/app_name"
android:exported="true"
android:isolatedProcess="true"
/>

Declare this in your manifest. Give a custom name to your process and make that process isolated and exported .

小开

Using the same process for the service and the activity and START_STICKY or START_REDELIVER_INTENT in the service is the only way to be able to restart the service when the application restarts, which happens when the user closes the application for example, but also when the system decides to close it for optimisations reasons. You CAN NOT have a service that will run permanently without any interruption. This is by design, smartphones are not made to run continuous processes for long period of time. This is due to the fact that battery life is the highest priority. You need to design your service so it handles being stopped at any point.

小开

Services are quite complicated sometimes.

When you start a service from an activity (or your process), the service is essentially on the same process.

quoting from the developer notes

Most confusion about the Service class actually revolves around what it is not:

A Service is not a separate process. The Service object itself does not imply it is running in its own process; unless otherwise specified, it runs in the same process as the application it is part of.

A Service is not a thread. It is not a means itself to do work off of the main thread (to avoid Application Not Responding errors).

So, what this means is, if the user swipes the app away from the recent tasks it will delete your process(this includes all your activities etc). Now, lets take three scenarios.

First where the service does not have a foreground notification.

In this case your process is killed along with your service.

Second where the service has a foreground notification

In this case the service is not killed and neither is the process

Third scenario If the service does not have a foreground notification, it can still keep running if the app is closed. We can do this by making the service run in a different process. (However, I've heard some people say that it may not work. left to you to try it out yourself)

you can create a service in a separate process by including the below attribute in your manifest.

android:process=":yourService"

or

android:process="yourService" process name must begin with lower case.

quoting from developer notes

If the name assigned to this attribute begins with a colon (':'), a new process, private to the application, is created when it's needed and the service runs in that process. If the process name begins with a lowercase character, the service will run in a global process of that name, provided that it has permission to do so. This allows components in different applications to share a process, reducing resource usage.

this is what I have gathered, if anyone is an expert, please do correct me if I'm wrong :)

小开

You must add this code in your Service class so that it handles the case when your process is being killed 

 @Override
public void onTaskRemoved(Intent rootIntent) {
Intent restartServiceIntent = new Intent(getApplicationContext(), this.getClass());
restartServiceIntent.setPackage(getPackageName());


PendingIntent restartServicePendingIntent = PendingIntent.getService(getApplicationContext(), 1, restartServiceIntent, PendingIntent.FLAG_ONE_SHOT);
AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
alarmService.set(
AlarmManager.ELAPSED_REALTIME,
SystemClock.elapsedRealtime() + 1000,
restartServicePendingIntent);


super.onTaskRemoved(rootIntent);
}
小开

Running an intent service will be easier. Service in creating a thread in the application but it's still in the application.

小开

From Android O, you cant use the services for the long running background operations due to this, https://developer.android.com/about/versions/oreo/background . Jobservice will be the better option with Jobscheduler implementation.


提交答案