Thứ Hai, 25 tháng 6, 2012

Using GPS to get current location – Android tutorial


Today we are going to see how to get our current location from the GPS.
1. Create a new Android project called UseGps, under the folder “Firstdroid.Tutorial.Gps”
2. In order to be able to access the GPS, we will have to add the permission in
the AndroidManifest.xml file:
This is how the complete file looks like
xml version=“1.0″ encoding=“utf-8″?>
<manifest xmlns:android=“http://schemas.android.com/apk/res/android”
package=“Firstdroid.Tutorial.Gps”
android:versionCode=“1″
android:versionName=“1.0″>
<application android:icon=“@drawable/icon” android:label=“@string/app_name”>
<activity android:name=“.UseGps”
android:label=“@string/app_name”>
<intent-filter>
<action android:name=“android.intent.action.MAIN” />
<category android:name=“android.intent.category.LAUNCHER” />
intent-filter>
activity>
application>
“android.permission.ACCESS_FINE_LOCATION”>
manifest>
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to   Now we need add a location listener, so each time the GPS senses a new location, this callback function will be called from the android system.
To do this, we need to add the fallowing code in the OnCreate method:
/* Use the LocationManager class to obtain GPS locations */
LocationManager mlocManager =
(LocationManager)getSystemService(Context.LOCATION_SERVICE);
LocationListener mlocListener new MyLocationListener();
mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, mlocListener);
We will add our own personal Location listener, so we can override some of the functions to do what we want. In our case we will just print a message to the screen in the fallowing cases:
· onLocationChanged ( Location Update )
· onProviderDisabled ( GPS Off )
· onProviderEnabled (GPS On )
And add another mandatory method, which will do nothing.
· onStatusChanged (We are not adding nothing here).
The UseGps.java file should look as fallows:
package Firstdroid.Tutorial.Gps;
import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;
public class UseGps extends Activity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/* Use the LocationManager class to obtain GPS locations */
LocationManager mlocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
LocationListener mlocListener new MyLocationListener();
mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, mlocListener);
}
/* Class My Location Listener */
public class MyLocationListener implements LocationListener
{
@Override
public void onLocationChanged(Location loc)
{
loc.getLatitude();
loc.getLongitude();
String Text = “My current location is: “ +
“Latitud = “ + loc.getLatitude() +
“Longitud = “ + loc.getLongitude();
Toast.makeText( getApplicationContext(),
Text,
Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider)
{
Toast.makeText( getApplicationContext(),
“Gps Disabled”,
Toast.LENGTH_SHORT ).show();
}
@Override
public void onProviderEnabled(String provider)
{
Toast.makeText( getApplicationContext(),
“Gps Enabled”,
Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras)
{
}
}/* End of Class MyLocationListener */
}/* End of UseGps Activity */
Now we want to test our application, for this we have to options:
1 – We can run our application in the Phone.
2 – Run the application with the simulator.
For the second case, to simulate a location update we need to connect to the simulator by telnet, and do the fallowing:
telnet localhost 5554
geo fix 30 28
You should het something like this in the simulator:
I hope this tutorial was helpful for you.

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