我正在尝试通过WiFi从Android虚拟设备获取当前位置，但是当我调试此程序时，它显示我在getLocation()中的被动网络提供程序中的位置为空。它给了我位置管理器的价值。在此我的gpsProvider和NetworkProvider都返回false值，提供者只是被动。
import java.util.List;
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.support.v4.app.FragmentActivity;
import android.util.Log;
public class ShowLocation extends FragmentActivity
{
Context context;
private LocationManager locationManager=null;
private LocationListener locationListener=null;
private Location location=null;
double latitude,longitude;
boolean gpsStatus=false,NetworkProvider=false,Status=false,Passiveprovider=false;
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
private Criteria criteria=null;
String Provider=null;
public void onCreate(Bundle state)
{
super.onCreate(state);
setContentView(R.layout.fragment_main);
context=getApplicationContext();
if(Status=checkStatus())
{
getLocation();
}
}
public boolean checkStatus()
{
boolean status1=false;
locationManager=(LocationManager)getSystemService(LOCATION_SERVICE);
List<String> provider =locationManager.getAllProviders();
System.out.println("Location Manager ="+provider);
for(String providername : provider)
{
if(providername.equals(LocationManager.GPS_PROVIDER))
{
gpsStatus=locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
status1=true;
}
if(providername.equals(LocationManager.NETWORK_PROVIDER))
{
NetworkProvider=locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
status1=true;
}
if(providername.equals(LocationManager.PASSIVE_PROVIDER))
{
Passiveprovider=locationManager.isProviderEnabled(LocationManager.PASSIVE_PROVIDER);
status1=true;
}
}
System.out.println("Network provider ="+NetworkProvider + "Gps Provider ="+gpsStatus + "PassiveProvider ="+Passiveprovider);
return status1;
}
public void getLocation()
{
locationListener=new LocationLis();
if(gpsStatus)
{
System.out.println("Gps Provider = "+gpsStatus);
Log.d("Gps is on","=" +gpsStatus);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,0,0,locationListener);
criteria=new Criteria();
Provider=locationManager.getBestProvider(criteria, true);
if(locationManager !=null)
{
location=locationManager.getLastKnownLocation(Provider);
if(location != null)
{
latitude=location.getLatitude();
longitude=location.getLongitude();
System.out.println("Gps Provider");
System.out.println(latitude +" "+longitude);
}
}
}
else if(NetworkProvider)
{
System.out.println("NetworkProvider"+NetworkProvider);
Log.d("Network is on", "="+NetworkProvider);
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,0,0,locationListener);
criteria=new Criteria();
Provider=locationManager.getBestProvider(criteria, true);
if(locationManager !=null)
{
location=locationManager.getLastKnownLocation(Provider);
if(location !=null)
{
latitude=location.getLatitude();
longitude=location.getLongitude();
System.out.println("Network Provider");
System.out.println(latitude +" "+longitude);
}
}
}
else if(Passiveprovider)
{
System.out.println("PassiveProvider"+Passiveprovider);
Log.d("Network is on", "="+Passiveprovider);
locationManager.requestLocationUpdates(LocationManager.PASSIVE_PROVIDER,0,0,locationListener);
criteria=new Criteria();
Provider=locationManager.getBestProvider(criteria, true);
// Here Provider is null
if(locationManager !=null)
{
location=locationManager.getLastKnownLocation(Provider);
if(location !=null)
{
latitude=location.getLatitude();
longitude=location.getLongitude();
System.out.println("Network Provider");
System.out.println(latitude +" "+longitude);
}
}
}
else
{
System.out.println("Provider r not available");
}
}
私有类LocationLis实现LocationListener {
@Override
public void onLocationChanged(Location location)
{
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
}
Manifest.xml档案
android:glEsVersion="0x00020000"
android:required="true" />
<uses-feature
android:name="android.hardware.wifi"
android:required="true" />
<permission
android:name="com.Priyank.priyankcurrentlocation.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-permission android:name="com.Priyank.priyankcurrentlocation.MAPS_RECEIVE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.INSTALL_LOCATION_PROVIDER" />
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="I have key with me." />
答案 0 :(得分：0)
允许getLastKnownLocation返回null。这意味着它最近没有找到一个位置，或者它所拥有的位置太旧了它不想返回它。你需要考虑到这种可能性。这是你需要小心使用getLastKnownLocation的两个原因之一（另一个原因是，即使它确实返回了一个值，它也可能是错误的 - 就像几个小时一样，没有新鲜的承诺）。