调用 Intent 时如何保持 MainActivity 运行？
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【中文标题】调用 Intent 时如何保持 MainActivity 运行？【英文标题】：How to keep a MainActivity running when an Intent is called? 【发布时间】：2018-05-11 02:23:42 【问题描述】：我有一个代码，当我调用地图活动时，它会接收纬度和经度并显示在地图上，但是当我在地图上时，onLocationChange 不会运行，因此它不会显示位置该人仅移动第一个属性，我如何更改它以使其不断发送属性？
import android.location.GpsSatellite;
import android.location.GpsStatus;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.content.Intent;
import android.Manifest;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.maps.model.LatLng;
public class MainActivity extends AppCompatActivity implements View.OnClickListener, LocationListener, GpsStatus.Listener
private LocationManager locManager; //Gerente de Localização
private LocationProvider locProvider; //Provedor de Localização
private static final int REQUEST_LOCATION = 2; //Utilizado nas requisições de localização
Intent map;
LatLng Local;
//Inicializado aqui para não dar crash caso o mapa seja chamado antes desses atributos serem inicializados.
double latitude = 0;
double longitude = 0;
//Pacote onde será armazenado o valor do LatLng.
Bundle args = new Bundle();
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Instância dos buttons:
Button map = (Button)findViewById(R.id.button_map);
map.setOnClickListener(this);
Button gnss = (Button)findViewById(R.id.button_gnss);
gnss.setOnClickListener(this);
Button config = (Button)findViewById(R.id.button_config);
config.setOnClickListener(this);
Button credits = (Button)findViewById(R.id.button_credits);
credits.setOnClickListener(this);
//Fim Instância dos Buttons
//O Gerente recebe uma location
locManager = (LocationManager)getSystemService(LOCATION_SERVICE);
@Override
public void onClick(View view)
switch(view.getId())
case R.id.button_map:
Local = new LatLng(latitude, longitude);
//Pacote inicializado com o LatLng
args.putParcelable("Latlng", Local);
//Criar tela relativa ao mapa
map = new Intent(this, MapsActivity.class);
//O pacote é passado para a Intent referente ao mapa
map.putExtra("bundle", args);
startActivity(map);
break;
case R.id.button_gnss:
/*Intent gnss = new Intent(this, GnssActivity.class);
startActivity(gnss);
*/
break;
case R.id.button_config:
Intent config = new Intent(this, SettingsActivity.class);
startActivity(config);
break;
case R.id.button_credits:
Intent credits = new Intent(this, CreditsActivity.class);
startActivity(credits);
break;
@Override
protected void onResume()
super.onResume();
if (ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION) ==
PackageManager.PERMISSION_GRANTED)
// A permissão foi dada
ativaGPS();
else
// Solicite a permissão
ActivityCompat.requestPermissions(this,
new String[]Manifest.permission.ACCESS_FINE_LOCATION,
REQUEST_LOCATION);
@Override
protected void onPause()
super.onPause();
desativaGPS();
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults)
if (requestCode == REQUEST_LOCATION)
if(grantResults.length == 1 && grantResults[0] ==
PackageManager.PERMISSION_GRANTED)
// O usuário acabou de dar a permissão
ativaGPS();
else
// O usuário não deu a permissão solicitada
Toast.makeText(this, "Sua localização não será mostrada", Toast.LENGTH_SHORT).show();
finish();
//Ativa o GPS
public void ativaGPS()
try
locProvider = locManager.getProvider(LocationManager.GPS_PROVIDER);
locManager.requestLocationUpdates(locProvider.getName(), 30000, 1, this);
catch (SecurityException e)
e.printStackTrace();
//Desativa o GPS
public void desativaGPS()
try
locManager.removeUpdates(this);
catch (SecurityException e)
e.printStackTrace();
public void onGpsStatusChanged(int event)
// Alguma mudança no sistema GPS
// A aplicação deverá chamar o método da classe LocationManager para obter informações sobre o status do distema GPS.
TextView coords=(TextView)findViewById(R.id.text_view_coords);
String satInfo="PRN;Azimute;Elevação;SNR;Used in Fix\n";
try
GpsStatus gpsStatus=locManager.getGpsStatus(null);
catch (SecurityException e)
e.printStackTrace();
if (ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION) ==
PackageManager.PERMISSION_GRANTED)
GpsStatus gpsStatus = locManager.getGpsStatus(null);
Iterable<GpsSatellite> sats=gpsStatus.getSatellites();
for (GpsSatellite sat:sats)
// processe as informações de cada satélite
// Informações do sistema estão encapsuladas no objeto gpsStatus
// Alguma mudança no sistema GPS
// Informações do sistema estão encapsuladas no objeto gpsStatus
//Métodos criados automaticamente na implementação do Location Listener !
@Override
public void onLocationChanged(Location location)
TextView coords=(TextView)findViewById(R.id.text_view_coords);
latitude=location.getLatitude();
longitude=location.getLongitude();
//Cordenadas em DD
coords.setText("Latitude"+latitude +"\n"+"Longitude:"+longitude);
/*coords.setText("Latitude:"+Location.convert(latitude,Location.FORMAT_SECONDS)
+"\n" +
"Longitude:"+Location.convert(longitude,Location.FORMAT_SECONDS)); */
//Passar o Bundle referente ao LatLng criado anteriormente.
@Override
public void onStatusChanged(String s, int i, Bundle bundle)
@Override
public void onProviderEnabled(String s)
@Override
public void onProviderDisabled(String s)
// FIM dos Métodos criados automaticamente na implementação do Location Listener !
--------------------------地图活动-------- ----------------------
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback
private GoogleMap mMap;
double latitude;
double longitude;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
Bundle bundle = getIntent().getParcelableExtra("bundle");
LatLng objLatLng = bundle.getParcelable("Latlng");
latitude = objLatLng.latitude;
longitude= objLatLng.longitude;
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
@Override
public void onMapReady(GoogleMap googleMap)
float zoomLevel = 16.0f;
mMap = googleMap;
//Posição atual marcada no mapa referentes a marcação e setagem da posição atual na API do Google Maps
LatLng posAtual = new LatLng(latitude, longitude);
mMap.addMarker(new MarkerOptions().position(posAtual).title("Sua posição atual!"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(posAtual));
//This goes up to 21
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(posAtual, zoomLevel));
【问题讨论】：
【参考方案1】：您是否考虑过将 MapActivity 实现为覆盖 MainActivity 并且可以按需使其可见的片段？
然后，您可以在 MapActivity 中实现一个方法，您可以从 onLocationChanged() 调用该方法，它使所有必要的东西都显示在片段上的当前位置。
看看Fragments
在您的 MapActivity 中，您可以声明类似
public void locationChanged(double latitude, double longtitude)
this.latitude = latitude;
this.longtitude = longtitude
//All necessary code you need to update the location shown on the map
在 MainActivity 你声明
public class MapFragment extends AppCompatActivity implements View.OnClickListener, LocationListener, GpsStatus.Listener
private MapFragment mapFragment;
...
在您的 onCreate() 方法中，您设置片段的视图
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.mapFragment);
当你完成所有这些后，你可以在你的 onLocationChanged() 方法中调用你在 MapFragment 中声明的方法
@Override
public void onLocationChanged(Location location)
TextView coords=(TextView)findViewById(R.id.text_view_coords);
mapFragment.locationChanged(location.getLatitude(), location.getLongitude();
//Rest of your code as necessary
【讨论】：
【参考方案2】：是的，您可以一次运行两个活动，甚至更多。您所要做的就是在后台运行它们，然后您就可以使用 Service 在
查看文档android service documentation
虽然不是同时，但您也可以让活动与服务一起侦听，您可以尝试启动结果意图并在
中接收结果@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) /** you receive the result here**/
在活动结果中接收意图是有效的，因为大多数语音搜索应用、条形码扫描仪和地图都使用这种方法
【讨论】：
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