我不知道如何编写代码来选择可能的网络提供商，或者如果网络不可用，那么GPS提供商。 如何更改代码才能获得此代码。 这是我的第一个Android应用程序，我试图这样做，但我没有成功。
package com.example.googlemapslbs;
import java.util.List;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.widget.Toast;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import com.google.android.gms.maps.CameraUpdateFactory;
import android.location.Criteria;
import android.util.Log;
public class MainActivity extends Activity {
GoogleMap Map;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
// Load map
initilizeMap();
}
catch (Exception e) {
e.printStackTrace();
}
}
private void initilizeMap() {
if (Map == null) {
Map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();
// map type normal (other possible choices: hybrid, terrain, satellite)
Map.setMapType(GoogleMap.MAP_TYPE_NORMAL);
// enable my-location
Map.setMyLocationEnabled(true);
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
//
Criteria criteria = new Criteria();
String provider = locationManager.getBestProvider(criteria, true);
//getting Current Location
Location location = locationManager.getLastKnownLocation(provider);
if(location == null){
LocationListener locationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
double lat= location.getLatitude();
double lng = location.getLongitude();
LatLng ll = new LatLng(lat, lng);
Map.moveCamera(CameraUpdateFactory.newLatLngZoom(ll, 18));
}
@Override
public void onProviderDisabled(String provider) {}
@Override
public void onProviderEnabled(String provider) {}
@Override
public void onStatusChanged(String provider, int status,
Bundle extras) {}
};
//Log.d("APpln", "well hello there >>"+location);
//location updates - requestLocationUpdates(provider, minTime, minDistance, listener)
locationManager.requestLocationUpdates(provider, 20000, 0, locationListener);
}else{
double lat= location.getLatitude();
double lng = location.getLongitude();
LatLng ll = new LatLng(lat, lng);
//modify the map's camera - zoom 18
Map.moveCamera(CameraUpdateFactory.newLatLngZoom(ll, 18));
}
// Define a listener that responds to location updates
LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
// Called when a new location is found by the network location provider.
makeUseOfNewLocation(location);
}
private void makeUseOfNewLocation(Location location) {
double lat = location.getLatitude();
double lng = location.getLongitude();
LatLng ll = new LatLng(lat, lng);
Toast.makeText(getApplicationContext(), "Your Current Location \nLat: " + lat + "\nLng: " + lng, Toast.LENGTH_LONG).show();
}
public void onStatusChanged(String provider, int status, Bundle extras) {}
public void onProviderEnabled(String provider) {}
public void onProviderDisabled(String provider) {}
};
locationManager.requestLocationUpdates(locationManager.getBestProvider(criteria, true), 0, 0, locationListener);
// check if map is created successfully or not
if (Map == null) {
Toast.makeText(getApplicationContext(),
"ups... can not create map", Toast.LENGTH_SHORT)
.show();
}
}
}
@Override
protected void onResume() {
super.onResume();
initilizeMap();
}
}
答案 0 :(得分：1)
我刚刚完成了一个示例项目，用于理解Location Services的用法。我只是发布我的代码，随意使用它来满足您对Location Services工作的需求和理解。此代码将检查最佳可用位置服务提供商，并在设置关闭时将其打开。
public class DSLVFragmentClicks extends Activity implements LocationListener {
private final int BESTAVAILABLEPROVIDERCODE = 1;
private final int BESTPROVIDERCODE = 2;
LocationManager locationManager;
String bestProvider;
String bestAvailableProvider;
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == BESTPROVIDERCODE) {
if (requestCode != Activity.RESULT_OK || locationManager.isProviderEnabled(bestProvider)) {
Toast.makeText(getActivity(), "Error! Location Service " + bestProvider + " not Enabled", Toast.LENGTH_LONG).show();
} else {
getLocation(bestProvider);
}
} else {
if (requestCode != Activity.RESULT_OK || locationManager.isProviderEnabled(bestAvailableProvider)) {
Toast.makeText(getActivity(), "Error! Location Service " + bestAvailableProvider + " not Enabled", Toast.LENGTH_LONG).show();
} else {
getLocation(bestAvailableProvider);
}
}
}
public void getLocation(String usedLocationService) {
Toast.makeText(getActivity(), "getting Location", Toast.LENGTH_SHORT).show();
long updateTime = 0;
float updateDistance = 0;
// finding the current location
locationManager.requestLocationUpdates(usedLocationService, updateTime, updateDistance, this);
}
@Override
public void onCreate(Bundle savedState) {
super.onCreate(savedState);
setContentView(R.layout.main);
// set a Criteria specifying things you want from a particular Location Service
Criteria criteria = new Criteria();
criteria.setSpeedRequired(false);
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setCostAllowed(true);
criteria.setBearingAccuracy(Criteria.ACCURACY_HIGH);
criteria.setAltitudeRequired(false);
locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
// finding best provider without fulfilling the criteria
bestProvider = locationManager.getBestProvider(criteria, false);
// finding best provider which fulfills the criteria
bestAvailableProvider = locationManager.getBestProvider(criteria, true);
String toastMessage = null;
if (bestProvider == null) {
toastMessage = "NO best Provider Found";
} else if (bestAvailableProvider != null && bestAvailableProvider.equals(bestAvailableProvider)) {
boolean enabled = locationManager.isProviderEnabled(bestAvailableProvider);
if (!enabled) {
Toast.makeText(getActivity(), " Please enable " + bestAvailableProvider + " to find your location", Toast.LENGTH_LONG).show();
Intent mainIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivityForResult(mainIntent, BESTAVAILABLEPROVIDERCODE);
} else {
getLocation(bestAvailableProvider);
}
toastMessage = bestAvailableProvider + " used for getting your current location";
} else {
boolean enabled = locationManager.isProviderEnabled(bestProvider);
if (!enabled) {
Toast.makeText(getActivity(), " Please enable " + bestProvider + " to find your location", Toast.LENGTH_LONG).show();
Intent mainIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivityForResult(mainIntent, BESTPROVIDERCODE);
} else {
getLocation(bestProvider);
}
toastMessage = bestProvider + " is used to get your current location";
}
Toast.makeText(getActivity(), toastMessage, Toast.LENGTH_LONG).show();
return true;
}
});
}
@Override
public void onLocationChanged(Location location) {
Log.d("Location Found", location.getLatitude() + " " + location.getLongitude());
// getting the street address from longitute and latitude
Geocoder geocoder = new Geocoder(getActivity(), Locale.getDefault());
String addressString = "not found !!";
try {
List<Address> addressList = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
StringBuilder stringBuilder = new StringBuilder();
if (addressList.size() > 0) {
Address address = addressList.get(0);
for (int i = 0; i < address.getMaxAddressLineIndex(); i++) {
stringBuilder.append(address.getAddressLine(i)).append("\n");
stringBuilder.append(address.getLocality()).append("\n");
stringBuilder.append(address.getPostalCode()).append("\n");
stringBuilder.append(address.getCountryName()).append("\n");
}
addressString = stringBuilder.toString();
locationManager.removeUpdates(this);
}
} catch (IOException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
Toast.makeText(getActivity(), " Your Location is " + addressString, Toast.LENGTH_LONG).show();
}
@Override
public void onStatusChanged(String s, int i, Bundle bundle) {
//To change body of implemented methods use File | Settings | File Templates.
}
@Override
public void onProviderEnabled(String s) {
//To change body of implemented methods use File | Settings | File Templates.
}
@Override
public void onProviderDisabled(String s) {
//To change body of implemented methods use File | Settings | File Templates.
}
}
如果您不理解其中的任何部分，请随时提出。