无法使Android.os.Handler继续运行

Question

So, I have a service I need to keep running in order to send an AYT to a device and report on the connection (basically whether it's up or down) at regular intervals. I have a setup right now, which works, however after about 10 or 15 minutes, it just ceases to run. It's using a HandlerThread, Handler and Runnable to start the service, which does its work, then stops itself.

MainActivity.java snippets:

private HandlerThread hThread = new HandlerThread("MaintainConnection");
private Handler h;
private Runnable hTask = new Runnable() {
    @Override
    public void run() {
        startService(new Intent(getApplicationContext(), MaintainConnectionService.class));
        h.postDelayed(this, 2000);
    }
};

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    hThread.start();
    h = new Handler(hThread.getLooper());
    /* OTHER CODE GOES HERE */
}

@Override
protected void onPause() {
    super.onPause();
    Log.v(TAG, "I am in onPause");
    h.removeCallbacks(hTask);
}

@Override
protected void onResume() {
    super.onResume();
    Log.v(TAG, "I am in onResume");
    h.post(hTask);
}

@Override
protected void onStop() {
    super.onStop();
    Log.v(TAG, "I am in onStop");
    h.removeCallbacks(hTask);
}

MaintainConnectionService.java

public class MaintainConnectionService extends IntentService {

    public MaintainConnectionService() {
        super(MaintainConnectionService.class.getName());
    }

    private static final String TAG = "MaintainConnectionSVC";

    public static Handler UIHandler;
    static {
        UIHandler = new Handler(Looper.getMainLooper());
    }

    public static void runOnUI(Runnable runnable) {
        UIHandler.post(runnable);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        try {
            if (Comms.telnet.sendAYT(Comms.AYT_TIMEOUT)) {
                Log.d(TAG, "Sent AYT to => " + Comms.telnet.getRemoteAddress() + ":" + Comms.telnet.getRemotePort());
                runOnUI(new Runnable() {
                    public void run() {
                        ColourControlFragment.connStat.setBackgroundColor(Color.GREEN);
                        ColourControlFragment.connStatTxt.setText("Connection Established");
                    }
                });
            } else {
                runOnUI(new Runnable() {
                    public void run() {
                        ColourControlFragment.connStat.setBackgroundColor(Color.YELLOW);
                        ColourControlFragment.connStatTxt.setText("Attempting Reconnect");
                    }
                });
            }
        } catch (Exception e) {
            Log.e(TAG, "Failed to send AYT to: " + Comms.TELNET_ADDRESS);
            runOnUI(new Runnable() {
                public void run() {
                    ColourControlFragment.connStat.setBackgroundColor(Color.RED);
                    ColourControlFragment.connStatTxt.setText("Not Connected");
                }
            });
            startService(new Intent(getApplicationContext(), EstablishConnectionService.class));
        }
        stopSelf();
    }
}

It all appears to work as expected, however as I said, after around 10 or 15 minutes, with no warning, it goes to the "Yellow" state (Attempting Reconnect) and stays there. If I close the app and restart it, it resumes working.

Any way to prevent threads being killed? Any suggestions on a better way to monitor the connection?

I've tried plain Thread s and Timer s, to no avail.

Answer 1

The Handler in your Activity should be static, otherwise you have the risk of leaking your Activity.

Also, if you remove callbacks in onResume and onPause (doing so in both does not make sense btw), it does make sense that you no longer receiving any messages.