定期在后台运行任务

Question

I want to run some task (fetching data from database) in background after 5 minutes interval. What should I use?

Answer 1

You can use TimerTask inside a service

 Timer timer = new Timer(); 
 timer.schedule( new YourTask(), 50000 );

Answer 2

Try this.

  Timer timer = new Timer();
  timer.scheduleAtFixedRate(new TimerTask() {

   @Override
   public void run() {
    //Do something

   }
  }, 0, 5000);

Answer 3

Use Async task:

pre Execute, do inBackground, Post Execute

With alarm Manager

Intent myIntent1 = new Intent(sign_in.this,MyNotificationService.class);
                        pendingintent2 = PendingIntent.getService(sign_in.this, 1,myIntent1, 1);
                        AlarmManager alarmManager1 = (AlarmManager) getSystemService(ALARM_SERVICE);
                        Calendar calendar1Notify = Calendar.getInstance();
                        calendar1Notify.setTimeInMillis(System.currentTimeMillis());
                        calendar.add(Calendar.SECOND, 20);

                        alarmManager1.set(AlarmManager.RTC_WAKEUP,calendar1Notify.getTimeInMillis(), pendingintent2);

                        long time = 300*1000;// 5 minutes repeat

 alarmManager1.setInexactRepeating(AlarmManager.RTC_WAKEUP, calendar1Notify.getTimeInMillis(),time,pendingintent2);

Add Permission in manifest

    <service android:name="com.example.MyNotificationService" >

        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </service>

Answer 4

you can use a timer task:

TimerTask scanTask;
final Handler handler = new Handler();
Timer t = new Timer();

public void doTask(){

scanTask = new TimerTask() {
        public void run() {
                handler.post(new Runnable() {
                        public void run() {
                            //your task(fetch data)
                        }
               });
        }};

    t.schedule(scanTask, 300000, 300000); 
 }

Answer 5

Please mind that Google ask you to run long operations on Service. Please read the articles below, to detech what service do you need (service, interservice)!

Intent Service going to shut down itself after the job is done. To fire a service in every 5mins to do the job , you can combine with a timer, as suggested above.

Mind before continue: Service belongs to the same thread, where you create it. So when you are about to developer your service please use a new Thread to start it. If you forget to do it, your service going to belong to the UI thread, mean you are in a trouble.... read first: http://developer.android.com/guide/components/services.html

developer guide: http://developer.android.com/reference/android/app/Service.html

Answer 6

You can use timer, it is not a problem but method within android do have some advantages

private int mInterval = 5000; // 5 seconds by default, can be changed later
  private Handler mHandler; 

  @Override 
  protected void onCreate(Bundle bundle) {
    ... 
    mHandler = new Handler(); 
  } 

  Runnable mStatusChecker = new Runnable() {
    @Override  
    public void run() { 
      updateStatus(); //this function can change value of mInterval. 
      mHandler.postDelayed(mStatusChecker, mInterval);
    } 
  }; 

  void startRepeatingTask() { 
    mStatusChecker.run(); 
  } 

  void stopRepeatingTask() { 
    mHandler.removeCallbacks(mStatusChecker);
  }