在应用启动期间获取当前位置

Posted 2023-04-14

【中文标题】在应用启动期间获取当前位置

【英文标题】：Get current location during app launch

【发布时间】：2012-08-30 10:49:43

【问题描述】：

美好的一天！ 我正在开发一个监控用户位置的安卓应用程序。我正在使用 LocationManager 获取用户位置，使用以下方法

public void onLocationChanged(Location theLocation) 

通过上述方法，每当有用户移动时，我都会收到位置坐标。

但是，现在我计划在用户登录应用后立即获取用户的位置。有什么方法可以通过 LocationManager 在我的应用启动后手动获取位置坐标？

【问题讨论】：

应用启动时不一定知道当前位置。所以getLastKnownLocation 可以是null 或非常过时，无论位置提供商如何。

见老post

【参考方案1】：

使用这种技术：

LocationManager locManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

boolean network_enabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

Location location;

if(network_enabled)

   location = locManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

if(location!=null)
   longitude = location.getLongitude();
   latitude = location.getLatitude();
                    

在这种情况下，您甚至不需要使用 GPS，只需移动网络即可。

不要忘记在 Manifest 中授予以下权限：

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

【讨论】：

getLastKnownLocation() 可能返回 null，在这种情况下这段代码会崩溃

它对我来说工作正常，只是集中精力我没有使用 GPS 提供商，我使用的是网络提供商。你测试了吗？？

您不能证明否定断言，例如“从不”。它可能会返回 null，您应该在调用 .getLongitude()

之前通过检查 location 是否为 null 来进行防御性编码

我取消了反对票，但我并不是要给它+1。事实是，“我现在想要位置”的答案是“好吧，很难，你不能总是拥有它，你必须等到 onLocationChanged() 被触发”它是事件驱动的，如果没有 GPS 或网络信号当您打开手机运行应用程序时，您很不走运。无论如何，您添加了空检查，这很好

感谢工作正常，你拯救了我的白天，黑夜等等：D

【参考方案2】：

试试这个代码。希望它会起作用

import android.app.Activity;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;

public class MainActivity extends Activity implements LocationListener 

private LocationManager locationManager;
private String provider;
@Override
public void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    provider = locationManager.getBestProvider(criteria, false);
    Location location = locationManager.getLastKnownLocation(provider);
    if (location != null) 
        System.out.println("Provider " + provider + " has been selected.");
        onLocationChanged(location);
       else 
        System.out.println("Location not avilable");
      



protected void onResume() 
    super.onResume();
    locationManager.requestLocationUpdates(provider, 400, 1, (LocationListener) this);
  

  /* Remove the locationlistener updates when Activity is paused */
  @Override
  protected void onPause() 
    super.onPause();
    locationManager.removeUpdates((LocationListener) this);
  
public void onLocationChanged(Location location) 
    double lat = (double) (location.getLatitude());
    double lng = (double) (location.getLongitude());
    Toast.makeText(getApplicationContext(), lat+"----"+lng,Toast.LENGTH_LONG).show();
    Log.i("Latitude------------", "Lattitude:" +lat);
    Log.i("Longitude-------------", "Longitude:" +lng);
  

@Override
public void onProviderDisabled(String arg0) 
    // TODO Auto-generated method stub



@Override
public void onProviderEnabled(String arg0) 
    // TODO Auto-generated method stub



@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) 
    // TODO Auto-generated method stub


    

必须添加所需的权限

【参考方案3】：

这就是我所做的... 1)mainactiviy.java

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity 

@Override
public void onCreate(Bundle savedInstanceState) 
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button gpsButton = (Button) findViewById(R.id.getloc);

gpsButton.setOnClickListener(new Button.OnClickListener() 
public void onClick(View v)
    LoadCoords();
);


@Override
public boolean onCreateOptionsMenu(Menu menu) 
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;


public void LoadCoords()
EditText locn = (EditText)findViewById(R.id.text1);
EditText locn1 = (EditText)findViewById(R.id.text2);
GPSTracker gps = new GPSTracker(this);
if(gps.canGetLocation)
Double latPoint=gps.getLatitude(); 
Double lngPoint =gps.getLongitude();   

locn.setText(latPoint.toString());
locn1.setText(lngPoint.toString());

另一个文件 2)GPSTracker.java

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;
import android.util.Log;

public class GPSTracker extends Service implements LocationListener
private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

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;

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;
        // First get location from Network Provider
        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;

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;

@Override
public void onLocationChanged(Location location) 


@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;

如果有效请回复...

【讨论】：

别忘了添加权限

权限>

【参考方案4】：

    ActivityCompat.requestPermissions(MapsActivity.this,new String[]Manifest.permission.ACCESS_FINE_LOCATION, 1);

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
    
        /*
        tvLatitud.setText("No se tienen permisos");
        ...
         */

        return;
    else
    
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        latitude = location.getLatitude();
        longitude =  location.getLongitude();