Question

我正在编写一个位置服务应用程序，用于记录用户每分钟都在哪里。我应该为GPS流程创建服务吗？或者只是在Activity上创建LocationManager？哪一个更好？

此外，我试图通过按下硬件主页按钮来隐藏应用程序并在设置 - ＆gt;处关闭GPS。地点。我发现应用程序在一小时内自动关闭。是否可以保持应用程序始终存在？

Answer 1

我强烈建议至少创建gps作为活动中的一个线程，如果你想要光滑的话将它设置为服务并从asynctask内部广播意图。如果要将其用于其他应用程序或其他活动，将其设置为服务会使其模块化。这就是我实施它的方式。

如果你从服务而不是你的活动中运行它，它也更容易控制你的gps读数的生命周期，所以如果你切换活动等服务不会中断。下面的asynctask部分的例子：

    /** Begin async task section ----------------------------------------------------------------------------------------------------*/
    private class PollTask extends AsyncTask<Void, Void, Void> { //AsyncTask that listens for locationupdates then broadcasts via "LOCATION_UPDATE" 
        // Classwide variables
        private boolean trueVal = true;
        Location locationVal;
        //Setup locationListener
        LocationListener locationListener = new LocationListener(){ //overridden abstract class LocationListener
            @Override
            public void onLocationChanged(Location location) {
                handleLocationUpdate(location);
            }
            @Override
            public void onProviderDisabled(String provider) {
            }
            @Override
            public void onProviderEnabled(String provider) {
            }
            @Override
            public void onStatusChanged(String provider, int status,
                    Bundle extras) {
            }
        };

        /** Overriden methods */
        @Override 
        protected Void doInBackground(Void... params) { 
            //This is where the magic happens, load your stuff into here
            while(!isCancelled()){ // trueVal Thread will run until you tell it to stop by changing trueVal to 0 by calling method cancelVal(); Will also remove locationListeners from locationManager
                Log.i("service","made it to do in background");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                }
            return null; 

        }

        @Override
        protected void onCancelled(){
            super.onCancelled();
            stopSelf();
        }

        @Override
        protected void onPreExecute(){ // Performed prior to execution, setup location manager
            locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
            if(gpsProvider==true){
                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
            }
            if(networkProvider==true){
                locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);
            }
        }

        @Override 
        protected void onPostExecute(Void result) { //Performed after execution, stopSelf() kills the thread
            stopSelf(); 
        } 

        @Override
        protected void onProgressUpdate(Void... v){ //called when publishProgress() is invoked within asynctask
                //On main ui thread, perform desired updates, potentially broadcast the service use notificationmanager
                /** NEED TO BROADCAST INTENT VIA sendBroadCast(intent); */
                Intent intent = new Intent(LOCATION_UPDATE);
                //Put extras here if desired
                intent.putExtra(ACCURACY, locationVal.getAccuracy()); // float double double long int
                intent.putExtra(LATITUDE, locationVal.getLatitude());
                intent.putExtra(LONGITUDE, locationVal.getLongitude());
                intent.putExtra(TIMESTAMP, locationVal.getTime());
                intent.putExtra(ALTITUDE,locationVal.getAltitude());
                intent.putExtra(NUM_SATELLITES,0);/////////////****TEMP
                sendBroadcast(intent); //broadcasting update. need to create a broadcast receiver and subscribe to LOCATION_UPDATE
                Log.i("service","made it through onprogress update");
        }

        /** Custom methods */

        private void cancelVal(){ //Called from activity by stopService(intent) --(which calls in service)--> onDestroy() --(which calls in asynctask)--> cancelVal()
            trueVal = false;
            locationManager.removeUpdates(locationListener);
        }

        private void handleLocationUpdate(Location location){ // Called by locationListener override.
            locationVal = location;
            publishProgress();
        }

    }

我应该为GPS跟踪APP创建服务吗？

1 个答案: