获取Android中的当前位置

Question

I have tried following code but not getting current location.
When I manual set location at emulator control then I get such location but not getting current location .I get null location.

• How to get current location?
• Is there any other way to get current location?

This is my code:

package com.p;
import android.app.Activity;
import android.os.Bundle;

import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;

import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
    public class GooglemapActivity extends Activity implements LocationListener {
   private TextView latituteField;
   private TextView longitudeField;
    private LocationManager locationManager;
    private String provider;
        EditText t;
   @Override
   public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
        setContentView(R.layout.main);



        latituteField = (TextView) findViewById(R.id.TextView02);
        longitudeField = (TextView) findViewById(R.id.TextView04);

        // Get the location manager
     locationManager =                  (LocationManager)getSystemService(Context.LOCATION_SERVICE);



    // Define the criteria how to select the locatioin provider -> use
    // default

            Criteria criteria = new Criteria();
           criteria.setAccuracy(Criteria.ACCURACY_FINE);
           criteria.setAltitudeRequired(false);//true if required
           criteria.setBearingRequired(false);//true if required
           criteria.setCostAllowed(true);
            criteria.setPowerRequirement(Criteria.POWER_LOW);
            provider = locationManager.getBestProvider(criteria, true);
            //provider=LocationManager.GPS_PROVIDER;
        Location location = locationManager.getLastKnownLocation(provider);
                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
             /*check provder*/boolean statusOfGPS    =locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);


            if ( statusOfGPS==true) {
        // Initialize the location fields
        if (location != null) {
               System.out.println("Provider " + provider + " has been      selected.");
                   double lat = (double) (location.getLatitude());
                    double lng = (double) (location.getLongitude());
                   latituteField.setText(Double.toString(lat));
                    longitudeField.setText(Double.toString(lng));
                } else {
                      latituteField.setText("Provider is not available");
                      longitudeField.setText("Provider not available");
                }


        }
        else
        {

        latituteField.setText("eeeeeeeee");
        longitudeField.setText("rrrrrrrrr");

        }
    }

    /* Request updates at startup */
    @Override
    protected void onResume() {
        super.onResume();
    locationManager.requestLocationUpdates(provider, 400, 1, this);
    }

    /* Remove the locationlistener updates when Activity is paused */
    @Override
    protected void onPause() {
        super.onPause();
    locationManager.removeUpdates(this);
    }

    public void onLocationChanged(Location location) {
            double lat = (double) (location.getLatitude());
         double lng = (double) (location.getLongitude());
        latituteField.setText(Double.toString(lat));
        longitudeField.setText(Double.toString(lng));
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    public void onProviderEnabled(String provider) {
        Toast.makeText(this, "Enabled new provider " + provider,
            Toast.LENGTH_SHORT).show();

    }

    public void onProviderDisabled(String provider) {
        Toast.makeText(this, "Disabled provider " + provider,
            Toast.LENGTH_SHORT).show();
    }
     }

I have added permissions in manifest.xml as below:

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

Answer 1

You won't get current location in emulator. You can set them through DDMS, and they will be your current location in case of a emulator.

Answer 2

Please, don't try to get last-known-location, most of the time it's stale and useless. Set up locationListener instead and wait for the location updates. This will get you your current location.

You may use this code to start listing for GPS updates and do something with the data you receive. It also prints messages in the log file for easy debugging. Please, note, this function does not return any results, it only starts listening to GPS . Results will be provided some time later in // do something here with the new location data part, when you may save them somewhere.

private void getGpsData() {
    locationManager = (LocationManager) owner.getSystemService(Context.LOCATION_SERVICE);

    locationListener = new LocationListener() {
        public void onLocationChanged(Location location) {
            Log.i(TAG, "location change:" + location.toString());

            String longitude = "Londitude: " + location.getLongitude();
            String latitude = "Latitude: " + location.getLatitude();

            if( location.hasAccuracy() ) {  // good enough?
                // do something here with the new location data
                ....
                //
                Log.i(TAG, "GPS listener done");
                locationManager.removeUpdates(this);    // don't forget this to save battery
            }
        }

        public void onStatusChanged(String provider, int status, Bundle extras) {
            Log.i(TAG, provider + " status:" + status);
        }

        public void onProviderEnabled(String provider) {
            Log.i(TAG, provider + " enabled");
        }

        public void onProviderDisabled(String provider) {
            Log.i(TAG, provider + " disabled");
        }
    };
    Log.i(TAG,"GPS listener started");
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener );
}