问题
I have looked about and cannot find any direct threads regarding what I am looking for. I am trying to create an Android application which dials out an emergency number at the push of a button (which I have got working) but cannot get the location (displayed in Longitude and Latitude) to display, I have tried doing it with Toast and EditText boxes. I am new to Android development so wanted to start with something easy, but the LongLat part is being troublesome. Any help would be greatly appreciated.
Below is the code I have been tampering with in order to try and get it to grab the Long and Lat, then in another file I have been trying to use a click listener to assign it to a button so when the button is pressed (in main.xml) it will display the Long and Lat either in a textfield or in toast.
import android.app.Activity;
import android.location.Location;
import android.location.LocationListener;
import android.os.Bundle;
import android.widget.TextView;
import android.content.Context;
import android.location.LocationManager;
import android.location.Criteria;
public class EmergencyLocation extends Activity implements LocationListener {
private TextView latituteField;
private TextView longitudeField;
private LocationManager locationManager;
private String provider;
/** Called when the activity is first created. **/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
latituteField = (TextView) findViewById(R.id.TextView);
longitudeField = (TextView) findViewById(R.id.long_lat);
// Get the location manager
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// Define the criteria how to select the location provider -> use
// default
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
// Initialise the location fields
if (location != null) {
System.out.println("Provider " + provider + " has been selected.");
int lat = (int) (location.getLatitude());
int lng = (int) (location.getLongitude());
latituteField.setText(String.valueOf(lat));
longitudeField.setText(String.valueOf(lng));
} else {
latituteField.setText("Provider not available");
longitudeField.setText("Provider not available");
}
}
private void TextView() {
// TODO Auto-generated method stub
}
@Override
public void onLocationChanged(Location arg0) {
// TODO Auto-generated method stub
}
@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
}}
回答1:
First, you need to set up a LocationManager:
LocationManager manager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
// set preferred provider based on the best accuracy possible
Criteria fineAccuracyCriteria = new Criteria();
fineAccuracyCriteria.setAccuracy(Criteria.ACCURACY_FINE);
String preferredProvider = manager.getBestProvider(fineAccuracyCriteria, true);
Now, you have to create a LocationListener. In this case, it calls the method updateLocation():
LocationListener listener = new LocationListener() {
public void onLocationChanged(Location location) {
// called when a new location is found by the network location provider.
updateLocation(location);
}
public void onStatusChanged(String provider, int status, Bundle extras) {}
public void onProviderEnabled(String provider) {}
public void onProviderDisabled(String provider) {}
};
EDIT:
Then, you have to register the listener with your LocationManager (and try to get the cached location):
manager.requestLocationUpdates(preferredProvider, 0, 0, listener);
// get a fast fix - cached version
updateLocation(manager.getLastKnownLocation());
And finally, the updateLocation() method:
private void updateLocation(Location location) {
if (location == null)
return;
// save location details
latitude = (float) location.getLatitude();
longitude = (float) location.getLongitude();
}
EDIT2:
OK, just saw your code. In order to make it work, just move around a few bits:
/** Called when the activity is first created. **/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
latituteField = (TextView) findViewById(R.id.TextView);
longitudeField = (TextView) findViewById(R.id.long_lat);
// Get the location manager
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// Define the criteria how to select the location provider -> use
// default
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
locationManager.requestLocationUpdates(provider, 0, 0, this);
Location location = locationManager.getLastKnownLocation(provider);
onLocationChanged(location);
}
@Override
protected void onDestroy() {
super.onDestroy();
locationManager.removeUpdates(this);
}
@Override
public void onLocationChanged(Location location) {
if (location != null) {
System.out.println("Provider " + provider + " has been selected.");
int lat = (int) (location.getLatitude());
int lng = (int) (location.getLongitude());
latituteField.setText(String.valueOf(lat));
longitudeField.setText(String.valueOf(lng));
} else {
latituteField.setText("Provider not available");
longitudeField.setText("Provider not available");
}
}
Hope it helps!
回答2:
Quite easy. I use the locationListener as an attribute inside a Location class. Here's how I do it:
package com.rifsoft.android.helper.location;
import com.rifsoft.android.helper.IListener;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
public class Location implements IListener
{
public final static int IDX_LATITIDE = 0;
public final static int IDX_LONGITUDE = 1;
private double[] lastLocation = {0.0, 0.0};
private LocationManager locationManager = null;
private ILocation activity = null;
private LocationListener locationListener = new LocationListener()
{
public void onLocationChanged(android.location.Location location)
{
// TODO: http://developer.android.com/guide/topics/location/obtaining-user-location.html#BestEstimate
lastLocation[IDX_LATITIDE] = location.getLatitude();
lastLocation[IDX_LONGITUDE] = location.getLongitude();
activity.onLocationChange();
}
public void onStatusChanged(String provider, int status, Bundle extras) {}
public void onProviderEnabled(String provider) {}
public void onProviderDisabled(String provider) {}
};
/**
* Constructor, needs LocationManager
* @param activity Activity that will receive the notification when location has changed
* @param locationManager LocationManager
*/
public Location(final ILocation act, LocationManager lm) throws LocationException
{
if (lm == null)
{
throw new LocationException(LocationException.ERR_NULL_LOCATION_MANAGER);
}
if (act == null)
{
throw new LocationException(LocationException.ERR_NULL_ILOCATION);
}
locationManager = lm;
activity = act;
registerListener();
android.location.Location lastCachedLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (lastCachedLocation != null)
{
lastLocation[IDX_LATITIDE] = lastCachedLocation.getLatitude();
lastLocation[IDX_LONGITUDE] = lastCachedLocation.getLatitude();
}
}
/**
* Retuns last known most accurate location as latitude, longitude
* @return Latitude, Longitude
*/
public double[] getLastLocation()
{
return lastLocation;
}
@Override
public void registerListener()
{
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
@Override
public void unRegisterListener()
{
locationManager.removeUpdates(locationListener);
}
}
Then the activity.onLocationChange() goes like
public void onLocationChange()
{
locationUpdated = true;
double[] coordinates = location.getLastLocation();
EditText lon = (EditText) activity.findViewById(R.id.longitude_value);
lon.setText(String.valueOf(coordinates[Location.IDX_LONGITUDE]));
EditText lat = (EditText) activity.findViewById(R.id.latitude_value);
lat.setText(String.valueOf(coordinates[Location.IDX_LATITIDE]));
}
来源：https://stackoverflow.com/questions/8711075/print-longitude-and-latitude-in-textbox-android