Android - Background operation
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This document discusses different techniques for handling background operations and threads in Android, including AsyncTask, IntentService, and JobScheduler. AsyncTask is meant for simple operations that need to update the UI. IntentService provides a straightforward way to perform simple background tasks without affecting the UI. JobScheduler allows scheduling jobs that will be run under certain conditions like charging or idle state.
![AsyncTask example
private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
OkHttpClient client = new OkHttpClient();
Request request =new Request.Builder().url(urls[0]).build();
Response response = client.newCall(request).execute();
…..
}
@Override
protected void onPostExecute(String result) {
textView.setText(result);
}
}
Run your code as a callback on UI ThreadRun your code on a new Thread](https://image.slidesharecdn.com/backgroundoperation-170216134950/85/Android-Background-operation-7-320.jpg)
Android - Background operation
- 1. Background operation How to handle all your jobs +RobertoOrgiu @_tiwiz +MatteoBonifazi @mbonifazi
- 2. Threading & Background Tasks Multithreading is essential if you want an Android app with a great user experience, but how do you know which techniques can help solve your problem?
- 3. Android threads Android application has at least one main thread The runtime env manages the UI thread. Long-running foreground operations can cause problems and interfere with the responsiveness of your user interface, which can even cause system errors. Android offers several classes that help you off-load operations onto a separate thread that runs in the background.
- 4. AsyncTask
- 5. AsyncTask represents a convenient way to offload work from the main thread.
- 6. AsyncTask Is meant for simple operations Allows to run instructions in the background and to synchronize again with the main thread. It also reporting progress of the running tasks. AsyncTasks should be used for short background operations which need to update the user interface.
- 7. AsyncTask example private class DownloadWebPageTask extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... urls) { OkHttpClient client = new OkHttpClient(); Request request =new Request.Builder().url(urls[0]).build(); Response response = client.newCall(request).execute(); ….. } @Override protected void onPostExecute(String result) { textView.setText(result); } } Run your code as a callback on UI ThreadRun your code on a new Thread
- 8. Parallel execution - AsyncTask // ImageLoader extends AsyncTask DownloadWebPageTask imageLoader = new DownloadWebPageTask( imageView ); // Execute in parallel imageLoader.executeOnExecutor( AsyncTask.THREAD_POOL_EXECUTOR, "http://url.com/image.png" );
- 10. IntentService provides straightforward structure for running an operation on a single background thread.
- 11. IntentService Preferred way to perform simple background operations Allows it to handle long-running operations without affecting your user interface's responsiveness. It isn't affected by most user interface lifecycle events, so it continues to run in circumstances that would shut down an AsyncTask
- 12. IntentService Limitations ● It can't interact directly with your user interface. To put its results in the UI, you have to send them to an Activity. ● Work requests run sequentially. If an operation is running in an IntentService, and you send it another request, the request waits until the first operation is finished. ● An operation running on an IntentService can't be interrupted.
- 13. IntentService lifecycle public class RSSPullService extends IntentService { public RSSPullService() { super(RSSPullService.class.getName()); } @Override protected void onHandleIntent(Intent workIntent) { // Gets data from the incoming Intent String dataString = workIntent.getDataString(); ... // Do work here, based on the contents of dataString ... } Other callbacks of a regular Service component, such as onStartCommand() are automatically invoked by IntentService. Put here your background job
- 14. IntentService in the AndroidManifest <application android:icon="@drawable/icon" android:label="@string/app_name"> ... <!-- Because android:exported is set to "false", the service is only available to this app. --> <service android:name=".RSSPullService" android:exported="false"/> ... <application/> The Activity that sends work requests to the service uses an explicit Intent
- 15. Create a work request to the IntentService mServiceIntent = new Intent(getActivity(), RSSPullService.class); mServiceIntent.setData(Uri.parse(dataUrl)); ... // Starts the IntentService getActivity().startService(mServiceIntent);
- 16. Going forward Youtube Video https://www.youtube.com/watch?v=jtlRNNhane https://www.youtube.com/watch?v=9FweabuBi1U https://www.youtube.com/watch?v=tBHPmQQNiS8 Reference Link https://developer.android.com/guide/components/processes-and-threads.html https://developer.android.com/training/run-background-service/index.html https://developer.android.com/training/multiple-threads/index.html
- 17. JobScheduler
- 18. Creating a job public class AwesomeJobService extends JobService { @Override public boolean onStartJob(final JobParameters params) { //AWESOME STUFF HERE return true; // or false } @Override public boolean onStopJob(JobParameters params) { //AWESOME CLEANING HERE return false; //or true } }
- 19. Scheduling a job ComponentName component = new ComponentName(context, AwesomeJobService.class); JobInfo.Builder builder = new JobInfo.Builder(jobId, component) .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY) .setRequiresDeviceIdle(true) ... .setRequiresCharging(false); builder.setExtras(parameters); JobScheduler s = (JobScheduler) getSystemService(Context.JOB_SCHEDULER_SERVICE); s.schedule(builder.build());
- 20. Going forward - 2 Reference Link https://developer.android.com/topic/performance/scheduling.html https://developer.android.com/reference/android/app/job/JobScheduler.html https://github.com/googlesamples/android-JobScheduler/