I need a service to start at boot that periodically checks some database for newly posted data. If there is new data(that fits the correct parameters) I need to then start an activity to display this. I plan on having a notification in-between this to allow the user the choice of dismissing the new data, if they are uninterested or in the middle of some other task. I have some php on a server that I am using to query the database, it works but it is in an activity. I have read a lot on here about alarmManagers and broadcast receivers. I think I need a broadcast receiver that starts on boot, that will start the service that will check for updates, then start the activity if there are.
Thanks a lot
To get a start with broadcast receiver take a look here for example.
Get the service implemented. Take a look at IntentService. It offloads the work into a worker thread, so you don't need to care about that yourself.
Schedule the service to start itself periodically using AlarmManager. Don't forget about wake lock to wake the device if needed.
It is usually not a good idea to start any activities without user consent. Show a notification in the notification bar that some new data is available. When user taps on the notification you start the activity to show the data.
There is more to that you just have to start step by step and make it happen :)
Are you asking how to start the service at boot, or start an activity from the service?
For the later android start activity from service , and for the former Android -Starting Service at Boot Time
Related
I developed two apps(can be more in the future) which are using the same service. When I start one of the apps they should start the service(if not already started) and send the name of an activity to tell the Service that the app is available.
The service is located in a third project, which is implemented as a library in the apps. The service listens in the Background for an event and start one of the apps.
The problem now is, how I start the service.
I tried already startService and bindService:
startService:
Intent intent = new Intent(this.getApplicationContext(), DriverBackgroundListener.class);
intent.putExtra("className", "com.example.testProject.Activity1");
this.startService(intent);
Starts a new Service for both apps, because the service is not located in the same app. So 2 Services are running and listen for the same event.
bindService:
I implemented it with the help of a Messenger. (https://developer.android.com/guide/components/bound-services.html)
The Problem here is, that the Service will only run if minimum one Activity is bind to the service. But I need to finish the Activity so the user can use the device normaly. But that will unbind the service and shut it down.
I also have to run the Service after a reboot. But I guess that will work if I create a BroadcastReceiver which starts the activities after the device is booted.
Have anyone an idea how to handle this?
Thanks best regards
Fabian
If you start service and then bind to it with flag 0, it still work even after you disconnect from it. You can try to connect to service first and make a check in onServiceConnected(), and if not start service. Also take a look at AIDL https://developer.android.com/guide/components/aidl.html.
I am creating a notification app, which will alert user after they set a reminder notification. My current implementation logic is:
Create a Service, which starts running in background when user opens their app.
In onCreate() method of service, I am implementing a Timer task which will repeat after 5000ms interval and will call a method, which will check all reminders set by user and notify user if any reminder is set for current time.
I use broadcast receiver to run the service on Boot_Completed event, if in case user turns off their phone.
This implementation is working good, I have faced no issues with it, but my concern is that is this a good practice? Keeping in mind that service running and checking every 5 secs will consume battery. Also if user turns on Stamina Mode, Power saving mode or any such mode, will OS kill my service. Is there anything I can do to give priority to my Service not to be killed.
If there is any other more efficient way to implement this sort of task, I want to implement that in my project.
Looking forward for suggestions.
Much Appreciated.
best approach is wakeful intent service with alarm receiver as mentioned here
https://github.com/commonsguy/cwac-wakeful
all good but use AlarmManager.setRepeating() as timer. the intent come even if your app killed.
I have been going through this very short tutorialand I am confused as to what is the function of the service. I am also confused as to what is the function of the broadcast receiver.
I tried to do some research and here is what i understand:
- services run in the background, but... i don't understand why we need something
to run in the background to make the phone wake up at a certain time.
I "think" the broadcast receiver acts as some kind of catcher's mit, in that
when the pending intent is launched at a specific time, it catches it then
launches the service... how close am I to the truth ?
As i think that services are used for long running tasks and especially in those cases that run when your main activity is not running.
For this functionality we can use threads this make us to say that a thread is created inside our activity and it can't be active outside of the our main activity,
that is the drawback that's why we have services .
Document URL
Services can be used to run long running tasks independent of your screen flow. For example, consider your application require to communicate with a server via socket throughout its running duration, you can start a service to handle this. Imagine that against starting the socket and making connection at the start of every activity, and clean up when that activity stops.
Services by default run in the main thread. But you can start separate threads in a service context, just like you do in an Activity. If your background task can overlap across multiple activities, then it is better to start it in a Service context because every Thread/AsyncTask created retains the context that it is running. In that case your Activity will be retained even if user navigates to another activity because a thread started from that Activity is already running. If Activity is retained, it might prevent all its views, images getting garbage collected.
What Services can't do is to directly alter UI components. For that it needs to communicate with the currently running Activity context. In short, if your non UI task does overlap the life time of a particular Activity, it is better to shift that task to a Service.
What is the function of the service ?
A service is a component which runs in the background without direct interaction with the user.
As the service has no user interface, it is not bound to the lifecycle of an activity.
Services are used for repetitive and potentially long running operations, i.e., Internet downloads, checking for new data, data processing, updating content providers and the like.
TO READ: Service
What is the function of the broadcast receiver ?
Broadcast receivers are the second kind of component. Like services, they only exist in the background and don't interact with you directly. But unlike services, they can't stay running or perform long tasks: they exist to respond to events. And unlike activities and services, more than one broadcast receiver can be started in one go.
Each broadcast receiver can react straight away, for example by creating a notification, or it can start a service or an activity to take further action. As soon as the broadcast receiver has handled the event, it is stopped and will not run again until another similar event is broadcast.
TO READ: BroadcastReceiver
I don't understand why we need something to run in the background to
make the phone wake up at a certain time ?
We don't want that the application should necessarily be in the foreground to wake the phone up.
Moreover we want notifications in the background.
We started the service. Now even if we close the application, you can get the phone wake up notification. This is so useful.
Services are great to interact with a user through notifications (a way of alerting a user about an event that he needs to be informed about or even take some action on getting that information). Many a time, applications will need to run processes for a long time without any intervention from the user, or very rare interventions. These background processes need to keep running even when the phone is being used for other activities / tasks.
To accommodate for such a requirement, android has introduced the "Service" component.
It runs in the background until it stops itself. This means that a service could be keeping your phone awake (using a wake lock), running down the battery, or using lots of network data, without anything showing on the screen.
I "think" the broadcast receiver acts as some kind of catcher's mit,
in that when the pending intent is launched at a specific time, it
catches it then launches the service... how close am I to the truth ?
Correct, they are meant to respond to an intent (usually one sent by a service or a system event), do something, and be done. When an intent is broadcast via sendBroadcast, it will be sent to all receivers that have matching intent filters.
Service - is a component of android, which runs in the background with out any UI. By default service will run in Main thread only.
Thread - is not android component, but still one can use thread to do some background task. Using thread in place of service is discouraged
I see all the examples of AlarmManager being set by an Activity.
My question is this:
If my application sets a recurring AlarmManager, does that persist even after the application that started is is closed and removed from memory?
If not, how do I start an AlarmManager at a lower level that is started by Android at boot up and if it ever fails or dies or throws an exception is restarted without the user having to do anything?
Lastly, if the action I wish for the BroadcastReceiver to undertake has no visual components, do I still have to create a separate Activity for it? In my case I want there to be a background uploader that wakes up and looks into a folder and if it sees files in that folder, sends them off to the server. I don't need any feedback to the user.
So, my ideal would be to have a magical, OS based AlarmManager that calls an IntentService which just handles the uploading, but I'm unclear on how to get such an AlarmManager running in the first place.
TIA
Yes, AFAIK the alarms "survive" and keeps getting triggered, even after the activity that registered them ends. But they don't survive a phone reboot.
If I understands your problem correctly, I think you can achieve what your looking for by creating a project with a broadcast receiver that listens for android.intent.action.BOOT_COMPLETED intents and then (re-)register a repeating alarm, which in turns starts a (Intent)Service to do the uploading.
You don't need an activity, but you probably would want one anyway, to let the user temporarily disable the upload mechanism by checking off a checkbox, or something. It would probably also be nice to let the user choose the frequency of your alarm, i.e. how often the service should be started and look for new files to upload. This would also be a good place to register your alarm for the first time.
I agree with Nicolai that you'd have 2 broadcast receivers in your application :
one that re-register the alarm on boot
one that starts your service when triggered by the alarm
You could still have an activity but it shouldn't be started by the alarm receiver (hence the service) : instead, maybe launch a notification as you start your service, with the user having the possibility to launch the activity from the expanded message of the notification.
maybe also think about setInexactRepeating (instead of setRepeating) for your alarm, as well as using a worker thread to handle the long uploads (in case the user wants to use your activity in the main thread at the same time).
I am creating an app which needs to retrieve a textfile from a webserver.
I have the manual retrieving done, just that I am thinking of adding a service to make the service check for the textfile like every 5 minutes and then send a notification to the user when a textfile is detected.
Is it ok to use a service here or do I have to use other methods?
Because the service will be kept running.
The best way of doing this is setting a repeating alarm using AlarmManager, a PendingIntent and a BroadcastReceiver as well as a Service. That way you don't have the service running all the time.
So the AlarmManager fires off the PendingIntent which is then picked up by the BroadcastReceiver which then starts your Service to perform the task in the background using a Thread or AsyncTask etc. Also look at IntentService which runs a Looper to process an Intent and then shuts itself down.
This is a great use of a service. Just make sure to allow the user to enable or disable service component. Also, try to shut it down when its not necessary (when the user cannot react to it).