"Turn" Android development how to ensure service is not killed (Broadcast+system/app)

Service Introduction

1. Service

Each service must be declared by <service> in manifest.

Can be started by Contect.startservice and Contect.bindserverice.

As with other application components, it runs in the main thread of the process . This means that if the service requires a lot of time-consuming or blocking operations, it needs to be implemented in its child threads (or with a system-provided intentservice that inherits the service, which processes the data with its own new thread). " of course you can also startservice in a new thread, so the service is not mainthread "

2. Local Service Local Service for internal application

It can start and run until someone stops it or it stops itself. In this way, it starts with a call to Context.startservice () and ends with a call to Context.stopservice (). It can call Service.stopself () or Service.stopselfresult () to stop itself. No matter how many times the StartService () method is called, you only need to call once StopService () to stop the service.

"Some time-consuming tasks for implementing the application itself, such as querying the upgrade information, and not consuming the application such as the activity's thread, but the single-threaded background execution, so the user experience is better"

3. Remote Service Remote Service is used between applications within the Android system

It can be manipulated by its own defined and exposed interfaces. The client establishes a connection to the service object and invokes the service through that connection. The connection is established by calling the Context.bindservice () method to turn off Context.unbindservice ().

Multiple clients can bind to the same service. If the service is not loaded at this time, bindservice () loads it first.

"Can be reused by other applications, such as weather forecasting services, other applications do not need to write such services, call the existing can be"

4. Service life cycle

5. Service operation mode

Starting the service with StartService (), the system will search through the incoming intent for services related to the information in the intent. If the service does not start, run OnCreate first, and then run Onstartcommand (which can handle the intent and other parameters that are passed in at startup) until a significant call to StopService or stopself stops the service. No matter how many times you run StartService, StopService or stopself,service will stop whenever you call. Use the stopself (int) method to ensure that the intent is processed and then stopped. Onstartcommand is introduced to the service startup function after 2.0

The service is enabled with the Bindservice () method, and the caller is bound together with the service, and once the caller exits, the service terminates. Onbind () The method is only invoked when the service is started with the Context.bindservice () method. This method is called when the caller and the service are bound, and the Context.bindservice () method is called multiple times when the caller is tied to the service and does not cause the method to be called more than once. Using the Context.bindservice () method to start a service can only call the Onunbind () method to disassociate the caller from the service and call the OnDestroy () method at the end of the service.

5. The process with service has a high priority

The official documentation tells us that the Android system will try to keep the process running with the service as long as the service has been started (start) or the client is connected (Bindservice) to it. When memory is low, it needs to be maintained, and the process with the service has a higher priority.

1. If the service is calling the Oncreate,onstartcommand or Ondestory method, then the process used for the current service becomes the foreground process to avoid being killed.
2. If the current service has been started (start), the process that owns it has a lower priority than those visible to the user, but is more important than the invisible process, which means that the service is generally not killed.
3. If the client is already connected to service (Bindservice), the process that owns the service has the highest priority and can be considered to be visible.
4. If the service can use the startforeground (int, Notification) method to set the service as the foreground state, the system is considered to be visible to the user and does not killed when the memory is low.
5. If there are other application components running in the same process as service,activity, it will increase the importance of the process.

6. Guaranteed service not to be killed

Onstartcommand method, returning Start_sticky

Startcommond Several constant parameters introduction:

1, Start_sticky

After the service process is killed after running Onstartcommand, that will remain in the start state, but those incoming intent are not preserved. Shortly after the service tries to recreate it again , because it remains in the start state, it is guaranteed to call Onstartcommandafter the service is created. If no start command is passed to the service, that will get the intent to null.

2, Start_not_sticky

After the service process is killed after running Onstartcommand, and no new intent is passed to it. The service moves out of the start state and is not re-created until a new, obvious method (StartService) call is made. Because if no intent is passed, then the service will not start , that is, the period Onstartcommand will not receive any null intent.

3, Start_redeliver_intent

After the service process is killed after running Onstartcommand, the service is started again and the last intent is passed to Onstartcommand. The pass-through intent is not stopped until stopself (int) is called. If there is an unhandled intent after the kill,

The service will start automatically after the kill. Therefore, Onstartcommand does not receive any null intent.

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1. @Override
2. public int Onstartcommand (Intent Intent, int flags, int startid) {
3. Flags = Start_sticky;
4. return Super.onstartcommand (intent, flags, Startid);
5. }

"Conclusion" manual return Start_sticky, pro-Test when the service is killed due to insufficient memory, when the memory is again, the service is re-created, it is good, but can not be guaranteed to be rebuilt under any circumstances, such as the process was killed ....

Improve service Priority

1. <service
2. Android:name="Com.dbjtech.acbxt.waiqin.UploadService"
3. android:enabled="true" >
4. <intent-filter android:priority="> "
5. <action android:name="Com.dbjtech.myservice"/>
6. </intent-filter>
7. </service>

"Conclusion" it appears that the priority attribute seems to apply only to broadcast, which may not be valid for service

Elevate Service Process Priority

Processes in Android are managed, and when the system process is tight, the process is automatically recycled according to the priority level. Android divides the process into 6 levels, which are ranked from highest to lowest in order of precedence:

1. Foreground process (Foreground_app)
2. Visual process (Visible_app)
3. Secondary service process (Secondary_server)
4. Background process (Hidden_app)
5. Content Provisioning Node (content_provider)
6. Empty process (Empty_app)

When the service is running in a low-memory environment, some of the existing processes will be killed. Therefore, the priority of the process will be important, and you can use Startforeground to put the service into the foreground state. This will reduce the chance of being killed at low memory.

Add the following code within the Onstartcommand method:

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2. Notification Notification = new Notification (R.drawable.ic_launcher,
4. GetString (R.string.app_name), System.currenttimemillis ());
8. Pendingintent pendingintent = pendingintent.getactivity (this, 0,
10. New Intent (This, Appmain.   Class), 0);
12. Notification.setlatesteventinfo (This, "Uploadservice", "please keep the program running in the background",
14. Pendingintent);
16. <span style="color: #ff0000;" > startforeground(0x111, notification);</span>

Note that in OnDestroy you also need Stopforeground (true), the runtime will see your app in the drop-down list:

"Conclusion" if under extreme low memory pressure, the service will still be killed, and will not necessarily be restart

Restart service in the OnDestroy method

Service +broadcast mode, that is, when the service goes ondestory, send a custom broadcast, when the broadcast, restart service;

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1. <receiver android:name="Com.dbjtech.acbxt.waiqin.BootReceiver" >
2. <intent-filter>
3. <action android:name="Android.intent.action.BOOT_COMPLETED"/>
4. <action android:name="Android.intent.action.USER_PRESENT"/>
5. <action android:name="Com.dbjtech.waiqin.destroy"/>//This is a custom action
6. </intent-filter>
7. </receiver>

At the time of OnDestroy:

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1. @Override
2. Public void OnDestroy () {
3. Stopforeground (true);
4. Intent Intent = new Intent ("Com.dbjtech.waiqin.destroy");
5. Sendbroadcast (Intent);
6. Super.ondestroy ();
7. }

In the Bootreceiver.

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2. Public class Bootreceiver extends Broadcastreceiver {
6. @Override
8. public void OnReceive (context context, Intent Intent) {
10. if (intent.getaction (). Equals ("Com.dbjtech.waiqin.destroy")) {
12. //todo
14. //write about restarting the service here
16. Startuploadservice (context);
18. }
22. }
26. }

can also be directly in the OnDestroy () StartService

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1. @Override
2. Public void OnDestroy () {
4. Intent sevice = new Intent (This, Mainservice.   Class);
5. This.startservice (sevice);
7. Super.ondestroy ();
8. }

"Conclusion" when using a third-party application such as a port steward or in a setting-application-Force stop, the app process may be killed directly, and the OnDestroy method cannot get in, so there is no guarantee ~.~

Application Plus Persistent property

Look at the Android documentation to know that when the process is inactive for a long time, or when the system needs resources, it automatically cleans up the portal, kills some of the service, and the invisible activity of the process. But if a process does not want to be killed (such as a data caching process, or a status monitoring process, or a remote service process), you can do this:

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1. <application
2. Android:name="Com.test.Application"
3. android:allowbackup="true"
4. android:icon="@drawable/ic_launcher"
5. Android:label="@string/app_name"
6. <span style="color: #ff0000;" > android:persistent="true"</span>
7. Android:theme="@style/apptheme" >
8. </application>

"Conclusion" it is said that this property can not be set randomly, but after the setting, it is found that the priority has improved a lot, perhaps the equivalent of a system-level process, but there is no guarantee of survival

Monitoring System broadcast Judging service status

Through some of the system's broadcasts, such as: Phone restart, interface wake-up, application status changes, and so on to monitor and capture, and then determine whether our service is still alive, do not forget to add permissions ah.

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2. <receiver android:name="Com.dbjtech.acbxt.waiqin.BootReceiver" >
4. <intent-filter>
6. <action android:name="Android.intent.action.BOOT_COMPLETED"/>
8. <action android:name="Android.intent.action.USER_PRESENT"/>
10. <action android:name="Android.intent.action.PACKAGE_RESTARTED"/>
12. <action android:name="Com.dbjtech.waiqin.destroy"/>
14. </intent-filter>
16. </receiver>

In Broadcastreceiver:

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2. @Override
4. Public void OnReceive (context context, Intent Intent) {
6. if (Intent.ACTION_BOOT_COMPLETED.equals (Intent.getaction ())) {
8. System.out.println ("mobile phone is on ....");
10. Startuploadservice (context);
12. }
14. if (Intent.ACTION_USER_PRESENT.equals (Intent.getaction ())) {
16. Startuploadservice (context);
18. }
20. }

"Conclusion" this can be considered as a measure, but the sense of monitoring more can lead to service confusion, causing a lot of inconvenience

install apk to/system/app and change to system-level application
This method is not recommended, because if your app is for the user, it is not appropriate, I am to give the test sister to use, the purpose of this app is very simple, open after opening service and can guarantee the background resides, boot from start. But yesterday found that if her Huawei mobile phone for a long time off, and then reopen, we apply the service will not start, it seems that the broadcast can not receive the ~ rage, intended to become a system application.
Premise: Root over the phone 1, the code is written, packaged and exported apk,copy to the phone SD card root directory. 2, mobile phone connection eclipse,cmd:adb shell3, switch root mode, input: SU (if root is not error) 4, set the system to read and Write permissions:mount–o remount Rw/system(System defaults to read-only and cannot be written, this step is critical)
5,CD to the SD card and directory, confirm that we have copied to the SD card root directory apk (generally storage/sdcard0)[Email protected]:/# CD STORAGE/SDCARD0
6, the most critical step, we want to copy the APK into the/system/app:
Found the copy command is invalid ~ Then we'll use push:
If there is an error: Device not found, then the phone download a root explorer, find apk,copy to System/app, through the app is easier. 7,system/app OK to have our apk, reboot the phone to put:
Settings-Application Management, check: You can see that our app has not been uninstalled and can only be deactivated
This time, even if the force stop, or shut down the service, restart the phone can still get up service~!

System-level apps, such as some third-party butler Software, can't kill us unless we deactivate the app or force it to stop (but my app can boot up).
ConclusionThis method is suitable for debugging to use, not a solution, you can try in the running interface: forced to shut down Sohu video two process, restart the phone, found that he can start again, but if replaced by our app, forced to stop, the process hangs, and then restart the phone, unable to start the ~


We study together, how can like Sohu video, open two processes, mutual monitoring, to achieve the maximum extent of survival, if this can be achieved, and, 360 and so on the same effect. transferred from: http://blog.csdn.net/mad1989/article/details/22492519

"Turn" Android development how to ensure service is not killed (Broadcast+system/app)