java - 计时器未在预定时间被调用

Question

我想每 10 分钟跟踪一次位置，并通过 TraceDelivery 异步任务将其发送到服务器。为此，我尝试使用服务和计时器每 10 分钟获取一次位置。

但是，当我从另一个 Activity 调用该服务时，它只能工作一次，即一次 TraceDelivery api 被调用，但不会再次调用。为了测试，我只给出了第二次延迟，但它仍然没有被再次调用。

此外，如果我检查 mLatLang 是否为 null，然后调用 TraceDelivery，它至少不会被调用一次。但如果 location 为 null，它会因 mLatLang 上的空指针而崩溃。

服务代码:

public class LocationTrackerService extends IntentService implements GoogleApiClient.ConnectionCallbacks,GoogleApiClient.OnConnectionFailedListener{

    private Handler handler;
    private Timer timer;
    private TimerTask timerTask;
    private GoogleApiClient mGoogleApiClient;
    Location mLastLocation;
    private LatLng mLatLang;
    LocationManager mLocationManager = null;
    boolean gps_enabled = false;
    boolean network_enabled = false;


    LocationListener[] mLocationListeners = new LocationListener[]{
            new LocationListener(LocationManager.NETWORK_PROVIDER),
            new LocationListener(LocationManager.GPS_PROVIDER)

    };

    /**
     * A constructor is required, and must call the super IntentService(String)
     * constructor with a name for the worker thread.
     */
    public LocationTrackerService() {
        super("HelloIntentService");
    }

    /**
     * The IntentService calls this method from the default worker thread with
     * the intent that started the service. When this method returns, IntentService
     * stops the service, as appropriate.
     */
    @Override
    protected void onHandleIntent(Intent intent) {
        // Normally we would do some work here, like download a file.
        // For our sample, we just sleep for 5 seconds.
        try {
            Thread.sleep(1000);

            buildGoogleApiClient();
            mGoogleApiClient.connect();

            handler = new Handler();

                initializeLocationManager();
                requestLocation();


                startTimer(intent.getStringExtra("dl_id"), intent.getStringExtra("pt_id"), intent.getStringExtra("ur_id"),intent.getStringExtra("address"),
                        intent.getStringExtra("api_key"));


        } catch (InterruptedException e) {
            // Restore interrupt status.
            Thread.currentThread().interrupt();
        }
    }
    public void startTimer(String dlId,String ptId,String urId,String add,String key) {
        //set a new Timer
        timer = new Timer();

        //initialize the TimerTask's job
        initializeTimerTask(dlId, ptId, urId,key);

        //schedule the timer, after the first 5000ms the TimerTask will run every 10000ms
        timer.schedule(timerTask, 1000, 1000);//
    }

    public void initializeTimerTask(final String dlId, final String ptId, final String urId, final String key) {

        timerTask = new TimerTask() {
            public void run() {

                //use a handler to run a toast that shows the current timestamp
                handler.post(new Runnable() {
                    public void run() {

                            TraceDeliveryAsyncTask traceDeliveryAsyncTask = new TraceDeliveryAsyncTask(LocationTrackerService.this);
                            traceDeliveryAsyncTask.execute(dlId, ptId, urId, String.valueOf(mLatLang.latitude),
                                    String.valueOf(mLatLang.longitude),"", key);

                            Log.e("timer","success");


                    }
                });
            }
        };
    }

    public void stoptimertask() {
        //stop the timer, if it's not already null
        if (timer != null) {
            timer.cancel();
            timer = null;
        }
    }

    protected synchronized void buildGoogleApiClient() {

        mGoogleApiClient = new GoogleApiClient.Builder(LocationTrackerService.this)
                .addConnectionCallbacks(LocationTrackerService.this)
                .addOnConnectionFailedListener(LocationTrackerService.this)
                .addApi(LocationServices.API)
                .build();
    }

    @Override
    public void onConnected(Bundle bundle) {
        // Toast.makeText(getActivity(),"onConnected",Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onConnectionSuspended(int i) {
        //  Toast.makeText(getActivity(),"onConnectionSuspended",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        //    Toast.makeText(getActivity(),"onConnectionFailed",Toast.LENGTH_SHORT).show();
    }

    private void initializeLocationManager() {
        // Log.e(Application.TAG, "initializeLocationManager");
        if (mLocationManager == null) {
            mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        }

        try {
            gps_enabled = mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
        } catch (Exception ex) {
        }

        try {
            network_enabled = mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        } catch (Exception ex) {
        }

        if (!gps_enabled && !network_enabled) {
            // notify user
            if(!CommonUtils.isGPSEnabled(getApplicationContext()))
                startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
        }

    }

    public class LocationListener implements android.location.LocationListener {

        public LocationListener() {
        }

        public LocationListener(String provider) {
            Log.e(TAG, "LocationListener " + provider);
            mLastLocation = new Location(provider);
        }

        @Override
        public void onLocationChanged(Location location) {
            Log.e(TAG, "onLocationChanged: " + location);

            //get current location

            if(mLastLocation != null && !mLastLocation.equals("")) {
                mLastLocation.set(location);
                mLatLang = new LatLng(mLastLocation.getLatitude(), mLastLocation.getLongitude());
            }
            else {

            }

        }

        @Override
        public void onProviderDisabled(String provider) {
            Log.e(TAG, "onProviderDisabled: " + provider);

        }

        @Override
        public void onProviderEnabled(String provider) {
            Log.e(TAG, "onProviderEnabled: " + provider);

        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            Log.e(TAG, "onStatusChanged: " + provider);
        }
    }

    //request for location, first by network, then by gps

    public void requestLocation() {

        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER, 0, 0,
                    mLocationListeners[0]);
        } catch (java.lang.SecurityException ex) {
            Log.i(TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "network provider does not exist, " + ex.getMessage());
        }

        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.GPS_PROVIDER, 0, 0,
                    mLocationListeners[1]);
        } catch (java.lang.SecurityException ex) {
            Log.i(TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "gps provider does not exist " + ex.getMessage());
        }
    }

}

我怎样才能实现这个目标？请帮忙解决这个问题。谢谢..

Answer 1

IntentService 将在完成 OnHandleIntent 中的任务后立即停止，

因此，不要使用 IntentService，而是尝试使用 Service 来进行长时间运行的操作。