I just started working with Android recently, so I don't know for
sure, but I think this might be because the timer used by Handlers is
only incremented when the CPU is running. When your phone becomes
inactive, the Android OS might shut down the CPU (this was mentioned
in one of the Google I/0 2008 talks: Android Anatomy and Physiology:
http://www.youtube.com/watch?v=G-36noTCaiA) which prevents the timer
used by your handler from being incremented.
Brian のメッセージ:
I rarely post to groups, because I can usually find the answer
somewhere on the web. So I apologize in advance if I have violated any
ettiquette. But this time I am truly stumped, and would appreciate any
help, insight, or suggestion from a more experienced Android
developer.
I've written a test service to understand how android implements a
service. I believe I understand the difference between
Context.startService and Context.bindService. If I am not mistaken,
Context.startService will tell android to keep the service running,
even after the Activity that started it has ended.
While testing the service, I have come across something unexpected.
The service appears to sleep or pause for a few hours, run a short
time, and then sleep for a few more hours, then run a short time, etc
when the phone has become inactive. In other words, when I am doing
things on the phone the service is doing what it is supposed to. But
after I have finished doing things on the phone and the screen goes
blank the service appears to sleep or pause. I don't know if I have
implemented the service wrong or if this is how Android services work.
The test service I have written simply sets a postDelayed handler to
increment++ a variable in the Runnable every minute, and then write
the value of that variable and a timestamp to a file (log.txt) on the
sd card. This how I know that the service appears to sleep. Because
there are gaps in the timstamp that correspond to when the phone was
inactive. If the service were truly active the whole time, there
should be a line item in the log.txt file every minute.
From the log.txt file below you can see that over an eleven hour
period there are only 36 line items with time stamps ranging from
10:27 PM through 9:23 AM. If the service was running and active the
whole time there should be over 600 lines in the text file. The phone
was on AC power the whole time so Android should not have tried to
stop services due to power issues. The phone was not used or touched
from about midnight to 9 the next morning, so there should not have
been a low resource clean up.
I have spent several days looking for an answer and everything I can
find seems to validate that when a service is started and not bound,
it will stay running (http://code.google.com/android/reference/android/
app/Service.html). However, it appears it does not. Unless I have
completely missed the ball on this.
I have included the service.java and activity.java as well as the log
file. Any help/ideas would be greatly appreciated. I am truly
stumped...
Here is the log.txt file
02/05/2009 10:27:02 PM: Service Created.
02/05/2009 10:27:02 PM: Service Started.
02/05/2009 10:27:07 PM: iCount = 1
02/05/2009 10:28:07 PM: iCount = 2
02/05/2009 10:29:07 PM: iCount = 3
02/05/2009 11:20:49 PM: iCount = 4
02/05/2009 11:31:11 PM: iCount = 5
02/05/2009 11:32:11 PM: iCount = 6
02/05/2009 11:33:16 PM: iCount = 7
02/05/2009 11:34:16 PM: iCount = 8
02/05/2009 11:35:16 PM: iCount = 9
02/05/2009 11:36:16 PM: iCount = 10
02/05/2009 11:37:16 PM: iCount = 11
02/05/2009 11:38:16 PM: iCount = 12
02/05/2009 11:39:16 PM: iCount = 13
02/05/2009 11:40:16 PM: iCount = 14
02/05/2009 11:41:16 PM: iCount = 15
02/05/2009 11:42:16 PM: iCount = 16
02/05/2009 11:43:17 PM: iCount = 17
02/05/2009 11:44:17 PM: iCount = 18
02/05/2009 11:45:17 PM: iCount = 19
02/05/2009 11:46:17 PM: iCount = 20
02/05/2009 11:47:17 PM: iCount = 21
02/05/2009 11:48:17 PM: iCount = 22
02/05/2009 11:55:58 PM: iCount = 23
02/06/2009 01:06:56 AM: iCount = 24
02/06/2009 03:07:41 AM: iCount = 25
02/06/2009 04:38:32 AM: iCount = 26
02/06/2009 06:54:49 AM: iCount = 27
02/06/2009 08:03:14 AM: iCount = 28
02/06/2009 08:57:50 AM: iCount = 29
02/06/2009 08:58:50 AM: iCount = 30
02/06/2009 08:59:50 AM: iCount = 31
02/06/2009 09:05:24 AM: iCount = 32
02/06/2009 09:06:24 AM: iCount = 33
02/06/2009 09:07:24 AM: iCount = 34
02/06/2009 09:08:24 AM: iCount = 35
02/06/2009 09:23:09 AM: iCount = 36
02/06/2009 09:23:17 AM: Service Destroyed.
Here is the service java file:
Java:
package bSoft.bService;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
public class bService extends Service
{
private long _iCount = 0;
private Handler objHandler = new Handler();
