Android location updates in a Service

问题

I want to do something like this:

When my application starts I want to start a Service which should check my location
When the application goes to background I want to stop the service

I have two major problems:

How can I detect that my application goes to background? I haver several activities, and I tried that in my MainActivity overriding onPause, but the onPause is also called when I start an other activity.
This problem is more important: How should my Service which checks for my location look like? I tried several approaches, but no success.

My Service looks like this, and it's not working. What should I change to make it work?

package com.pivoscore.service;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;

public class LocationService extends Service {

    private LocationListener locationListener;

    @Override
    public IBinder onBind(final Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(final Intent intent, final int flags, final int startId) {
        super.onStartCommand(intent, flags, startId);
        return Service.START_STICKY;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        final LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        this.locationListener = new MyLocationListener();
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 100, 0, this.locationListener);
    }

    private static class MyLocationListener implements LocationListener {

        @Override
        public void onLocationChanged(final Location location) {
        }

        @Override
        public void onProviderDisabled(final String provider) {
        }

        @Override
        public void onProviderEnabled(final String provider) {
        }

        @Override
        public void onStatusChanged(final String provider, final int status, final Bundle extras) {
        }

    }

}

回答1:

This Will Help exaclty what your requirment is but don't forget to Add the permission i've added in comment and also don't forget to added service tag in manifest File Code Snipet is Following

public class LocationService extends Service {
public static final String BROADCAST_ACTION = "Hello World";
private static final int TWO_MINUTES = 1000 * 60 * 2;
public LocationManager locationManager;
public MyLocationListener listener;
public Location previousBestLocation = null;

Intent intent;
int counter = 0;

@Override
public void onCreate() {
    super.onCreate();
    intent = new Intent(BROADCAST_ACTION);      
}

@Override
public void onStart(Intent intent, int startId) {      
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    listener = new MyLocationListener();        
    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, listener);
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listener);
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

protected boolean isBetterLocation(Location location, Location currentBestLocation) {
    if (currentBestLocation == null) {
        // A new location is always better than no location
        return true;
    }

    // Check whether the new location fix is newer or older
    long timeDelta = location.getTime() - currentBestLocation.getTime();
    boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
    boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
    boolean isNewer = timeDelta > 0;

    // If it's been more than two minutes since the current location, use the new location
    // because the user has likely moved
    if (isSignificantlyNewer) {
        return true;
    // If the new location is more than two minutes older, it must be worse
    } else if (isSignificantlyOlder) {
        return false;
    }

    // Check whether the new location fix is more or less accurate
    int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
    boolean isLessAccurate = accuracyDelta > 0;
    boolean isMoreAccurate = accuracyDelta < 0;
    boolean isSignificantlyLessAccurate = accuracyDelta > 200;

    // Check if the old and new location are from the same provider
    boolean isFromSameProvider = isSameProvider(location.getProvider(),
            currentBestLocation.getProvider());

    // Determine location quality using a combination of timeliness and accuracy
    if (isMoreAccurate) {
        return true;
    } else if (isNewer && !isLessAccurate) {
        return true;
    } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
        return true;
    }
    return false;
}

/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
    if (provider1 == null) {
      return provider2 == null;
    }
    return provider1.equals(provider2);
}

@Override
public void onDestroy() {       
   // handler.removeCallbacks(sendUpdatesToUI);     
    super.onDestroy();
    Log.v("STOP_SERVICE", "DONE");
    locationManager.removeUpdates(listener);        
}   

public static Thread performOnBackgroundThread(final Runnable runnable) {
    final Thread t = new Thread() {
        @Override
        public void run() {
            try {
                runnable.run();
            } finally {

            }
        }
    };
    t.start();
    return t;
}


public class MyLocationListener implements LocationListener
{

    public void onLocationChanged(final Location loc)
    {
        Log.i("**************************************", "Location changed");
        if(isBetterLocation(loc, previousBestLocation)) {
            loc.getLatitude();
            loc.getLongitude();             
            intent.putExtra("Latitude", loc.getLatitude());
            intent.putExtra("Longitude", loc.getLongitude());     
            intent.putExtra("Provider", loc.getProvider());                 
            sendBroadcast(intent);          
            /*final Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());         
            String Text = "";
            try {
                List<Address> addresses = geocoder.getFromLocation(loc.getLatitude(), loc.getLongitude(), 1);                
                Text = "My current location is: "+addresses.get(0).getAddressLine(0); 

            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Text = "My current location is: " +"Latitude = " + loc.getLatitude() + ", Longitude = " + loc.getLongitude();  
            }
            */
            //Toast.makeText( getApplicationContext(), "Location polled to server", Toast.LENGTH_SHORT).show();
        }                               
    }

    public void onProviderDisabled(String provider)
    {
        Toast.makeText( getApplicationContext(), "Gps Disabled", Toast.LENGTH_SHORT ).show();
    }


    public void onProviderEnabled(String provider)
    {
        Toast.makeText( getApplicationContext(), "Gps Enabled", Toast.LENGTH_SHORT).show();
    }


    public void onStatusChanged(String provider, int status, Bundle extras)
    {

    }

}

回答2:

Application is not a visual component in Android. It is divided into Activities, each of them run when visible, paused and destroyed otherwise. So, there is no concept of whole Application going to background, Activities are paused and resumed on the basis of their individual visibility and are completely independent of other Activities in this matter.
Your Service shall register with Location Manager in its onCreate(), unregister from the same in its onDestroy(). In its onBind() it shall return a Messenger object. And, in onLocationChanged() it should send a message through its shared Messenger. No need to use START_STICKY as you don't want Service running all the time.
The Activity (can be any activity in the App) just needs to call bindService() in its onStart(), The service will start if not already, and Activity will get a Messenger from service. Also, Activity should call unbindService() from its onStop(). The Service will automatically stop when nothing is bound to it.
If you need to do the stuff in point 3 at App (Task) level, implement the Application class, and use its onCreate() and onTerminate(). Application class is not paused or stopped like an Activity.

回答3:

I suggest you to use the latest location api provided by google(also compatible to version 2.2).

here is a example shows how to use that: https://github.com/chenjishi/android_location_demo

when your app run to background, you can call disconnect to stop the location update.

回答4:

Try This code.. By using this you can find whether your application is in foreground or background. Hope this will help you.

try {
    foreground = new ForegroundCheckTask().execute(ctx).get();
}

======================================


class ForegroundCheckTask extends AsyncTask<Context, Void, Boolean> {

@Override
protected Boolean doInBackground(Context... params) {
    final Context context = params[0].getApplicationContext();
    return isAppOnForeground(context);
}

private boolean isAppOnForeground(Context context) {
    ActivityManager activityManager = (ActivityManager) context
            .getSystemService(Context.ACTIVITY_SERVICE);
    List<RunningAppProcessInfo> appProcesses = activityManager
            .getRunningAppProcesses();
    if (appProcesses == null) {
        return false;
    }
    final String packageName = context.getPackageName();


    String activePackageName = activityManager.getRunningTasks(1).get(0).topActivity.getPackageName();
    if (activePackageName.equals(packageName)) {
        return true;
    }
    else{
        return false;
    }


}

}

来源：https://stackoverflow.com/questions/15066540/android-location-updates-in-a-service

标签

android

location

android-service