我创建App，每1分钟给我一次经度和经度。我必须每1分钟将这个位置信息更新到服务器。计时器运行完美。但是，当我关闭应用程序或从我最近打开的应用程序终止应用程序时，计时器不起作用。
即使关闭应用，我怎样才能在后台执行此操作？
GpsTracket.java
public class GPSTracker extends Service implements LocationListener {
private final Context mContext;
private final Handler _handler = new Handler();
private static int DATA_INTERVAL = 1 * 60 * 1000;
public static final long NOTIFY_INTERVAL =1 * 60 * 1000; // 60 seconds
// run on another Thread to avoid crash
private Handler mHandler = new Handler();
// timer handling
private Timer mTimer = null;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
private Handler handler = new Handler();
private long initial_time;
long timeInMilliseconds = 0L;
private Intent intent;
public static final String BROADCAST_ACTION = "com.example.gpstracking.AndroidGPSTrackingActivity";
@Override
public void onCreate() {
super.onCreate();
startService(new Intent(this, AndroidGPSTrackingActivity.class));
initial_time = SystemClock.uptimeMillis();
intent = new Intent(BROADCAST_ACTION);
handler.removeCallbacks(sendUpdatesToUI);
handler.postDelayed(sendUpdatesToUI, 1000);
if(mTimer != null) {
mTimer.cancel();
} else {
// recreate new
mTimer = new Timer();
}
// schedule task
mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 0, NOTIFY_INTERVAL);// 1 second
}
private Runnable sendUpdatesToUI = new Runnable() {
public void run() {
getLocation();
handler.postDelayed(this, 1000); // 1 seconds
}
};
public GPSTracker(Context context) {
this.mContext = context;
getLocation();
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(GPSTracker.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
@Override
public void onLocationChanged(Location location) {
}
public void notifyUser() {
NotificationManager notificationManager = (NotificationManager)this.getSystemService(Context.NOTIFICATION_SERVICE);
Intent intent = new Intent(GPSTracker.this, AndroidGPSTrackingActivity.class);
//use the flag FLAG_UPDATE_CURRENT to override any notification already there
PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
Notification notification = new Notification(R.drawable.ic_launcher, "Some Text", System.currentTimeMillis());
notification.flags = Notification.FLAG_AUTO_CANCEL | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_SOUND;
notification.setLatestEventInfo(this, "", "", contentIntent);
//10 is a random number I chose to act as the id for this notification
notificationManager.notify(10, notification);
}
@Override
public void onDestroy() {
super.onDestroy();
handler.removeCallbacks(sendUpdatesToUI);
}
class TimeDisplayTimerTask extends TimerTask {
@Override
public void run() {
// run on another thread
handler.post(new Runnable() {
@Override
public void run() {
// display toast
Toast.makeText(getApplicationContext(), getDateTime(),
Toast.LENGTH_SHORT).show();
}
});
}
private String getDateTime() {
// get date time in custom format
SimpleDateFormat sdf = new SimpleDateFormat("[yyyy/MM/dd - HH:mm:ss]");
return sdf.format(new Date());
}
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
}
AndroidGPSTrackingActivity.java
public class AndroidGPSTrackingActivity extends Activity {
Button btnShowLocation;
Geocoder geocoder;
List<Address> addresses;
private final Handler _handler = new Handler();
private static int DATA_INTERVAL = 1 * 60 * 1000;
// GPSTracker class
GPSTracker gps;
double longitude;
double latitude;
Calendar c;
SimpleDateFormat sdf;
String strDate;
Intent intent;
private Timer mTimer = null;
protected LocationManager locationManager;
private Handler handler = new Handler();
private long initial_time;
public static final long NOTIFY_INTERVAL = 60 * 1000;
public static final String BROADCAST_ACTION = "com.example.gpstracking.GPSTrackers";
String address,city,state,country,postalCode,knownName,city2;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
geocoder = new Geocoder(this, Locale.getDefault());
initial_time = SystemClock.uptimeMillis();
intent = new Intent(BROADCAST_ACTION);
handler.removeCallbacks(sendUpdatesToUI);
handler.postDelayed(sendUpdatesToUI, 1000 * 70);
if(mTimer != null) {
mTimer.cancel();
} else {
// recreate new
mTimer = new Timer();
}
// schedule task
mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 0, NOTIFY_INTERVAL);// 1 second
location();
btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
// show location button click event
btnShowLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// create class object
location();
}
});
}
class TimeDisplayTimerTask extends TimerTask {
@Override
public void run() {
// run on another thread
handler.post(new Runnable() {
@Override
public void run() {
// display toast
location();
}
});
}
}
public void location(){
gps = new GPSTracker(AndroidGPSTrackingActivity.this);
// check if GPS enabled
if(gps.canGetLocation()){
latitude = gps.getLatitude();
longitude = gps.getLongitude();
try {
addresses = geocoder.getFromLocation(latitude, longitude, 1);
Log.d("adddd", String.valueOf(addresses));
address = addresses.get(0).getAddressLine(0);
city = addresses.get(0).getAddressLine(1);
state = addresses.get(0).getAddressLine(2);
c = Calendar.getInstance();
sdf= new SimpleDateFormat("dd/MM/yyyy hh:mm a ");
strDate = sdf.format(c.getTime());
} catch (IOException e) {
e.printStackTrace();
}
// \n is for new line
Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude + address + "\n"
+city +" "+ state + "\n" + strDate
, Toast.LENGTH_LONG).show();
_handler.postDelayed(getData, DATA_INTERVAL);
}else{
// can't get location
// GPS or Network is not enabled
// Ask user to enable GPS/network in settings
gps.showSettingsAlert();
}
}
private Runnable sendUpdatesToUI = new Runnable() {
public void run() {
handler.postDelayed(this, 1000 * 60); // 1 seconds
}
};
public void notifyUser() {
NotificationManager notificationManager = (NotificationManager)this.getSystemService(Context.NOTIFICATION_SERVICE);
Intent intent = new Intent(AndroidGPSTrackingActivity.this, AndroidGPSTrackingActivity.class);
//use the flag FLAG_UPDATE_CURRENT to override any notification already there
PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
Notification notification = new Notification(R.drawable.ic_launcher, "Some Text", System.currentTimeMillis());
notification.flags = Notification.FLAG_AUTO_CANCEL | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_SOUND;
notification.setLatestEventInfo(this, city, state, contentIntent);
//10 is a random number I chose to act as the id for this notification
notificationManager.notify(10, notification);
}
@Override
public void onStop() {
super.onStop();
_handler.postDelayed(getData, DATA_INTERVAL);
//write your code here to start your service
}
@Override
public void onDestroy() {
startService(new Intent(this, Service.class));
super.onDestroy();
}
@Override
public void onPause() {
super.onPause();
startService(new Intent(this, GPSTracker.class));
location();
//write your code here to start your service
}
private final Runnable getData = new Runnable()
{
@Override
public void run()
{
location();
notifyUser();
}
};
}
请帮助。
答案 0 :(得分：3)
您必须创建扩展IntentService的后台服务，该服务每1分钟提供一次纬度和经度。
您可以在服务中使用Timer或ScheduledExecutorService每1分钟获取一次。
您已在AndroidGPSTrackingActivity课程中创建了计时器，而不是创建新服务并将所有与计时器相关的代码移至onStartCommand后台服务方法。
在AndroidGPSTrackingActivity开始您的后台服务。要自动重新启动服务，您必须在服务的onStartCommand方法中返回START_STICKY。
要创建Intent服务，请参阅https://developer.android.com/training/run-background-service/create-service.html
我希望它有所帮助！