Https and Android:

We all know that we have to secure our web service calls and its very easy to intercept these calls if they are not properly secured. But getting this to work on Android is not that straightforward. After some substantial amount of research I found the easy way to get it working and decided to save some time for my co android developers.


private static int NET_TIMEOUT = 30000;
private static int NETWORK_POOL = 4;
DefaultHttpClient client = getClient(ctx);
HttpGet getRequest = new HttpGet(url);

Instead of instantiating the DefaultHttpClient  I implemented my own getClient  which would return the custom HttpClient with the SocketFactory enabled.

private static DefaultHttpClient getClient(Context ctx) {
DefaultHttpClient client;
HttpParams httpParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParams, NET_TIMEOUT);
HttpConnectionParams.setSoTimeout(httpParams, NET_TIMEOUT);
ConnManagerParams.setMaxConnectionsPerRoute(httpParams,new ConnPerRouteBean(NETWORK_POOL));
HttpConnectionParams.setSocketBufferSize(httpParams, 8192);
SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", newSSLSocketFactory(ctx), 443));
ThreadSafeClientConnManager cm = new ThreadSafeClientConnManager(httpParams, registry);
client = new DefaultHttpClient(cm, httpParams);
return client;
}

registry.register(new Scheme(“https”, newSSLSocketFactory(ctx), 443)); is key here .

private static SSLSocketFactory newSSLSocketFactory(Context ctx)
{
try{
KeyStore trusted = KeyStore.getInstance("BKS");
InputStream in = ctx.getResources().openRawResource(R.raw.zynglstore);
try{
trusted.load(in,"changeme".toCharArray());
}finally{
in.close();
}
SSLSocketFactory mySslFactory = new SSLSocketFactory(trusted);
return mySslFactory;
}catch(Exception e){
throw new AssertionError(e);
}
}

Then coming back to the original code .

HttpResponse getResponse = client.execute(getRequest);
final int statusCode = getResponse.getStatusLine().getStatusCode();

Http Post also should work the similar way.

Hope this helps.

I have created the keystore using http://portecle.sourceforge.net/ ..Portcele. This is a very handy tool

Most of the android apps use the location-based services for geo coding to display things on Map. The three main classes that are used are

1.Location — This class represents a geographic location at a particular time

2.Location Manager – This class provides access to Android System Location services (Entry point)

3.LocationListener – This is an interface for receiving notifications from the Location Manager when ever the

location is changed.

The LocationManager needs to be initialized and its done the following way

locationmanager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

After the LocationManager is initialized the LocationProvider needs to be selected.The general way to find the proper location provider is to define the accuracy and the power requirement . This can be done as follows

android.location.Criteria --class is used for that

Criteria criteria = new Criteria();

criteria.setAccuracy(Criteria.ACCURACY_FINE);

criteria.setPowerRequirement(Criteria.POWER_LOW);

String locationProvider = locationmanager.getBestProvider(criteria,true);

so, then how do we retrieve the last Location ,,its simple ..the API provides us with a method called

getLastKnownLocation()

Location location = locationmanager.getLastKnownLocation(locationprovider);

and the latitude and the longitude can be retrieved by using

location.getLatitude() and location.getLongitude()

location.getExtras() can be used to retrieve the satellite information

2. How does the location get updated when ever the location is changed ..

Answer : The LocationListener interface is used to receive notifications when the location is changed.The locationManagers requestLocationUpdates() method needs to be called after the locationprovider is initialized to specify when the current activity is to be notified of changes.

the method requestLocationUpdates() takes the following parameters

1. provider — locationProvider

2. minTIme – The minimum time between updates in milliseconds

3. minDistance – The minimum distance change before updates in meters

4. listener  – the location listener that receive updates

This is called in the onCreateMethod

locationmanager.requestLocationUpdates(locationprovider,3000,3.0,this)

parameters explained :

1.locationprovider — the same locationprovider that’s initialized for the locationmanager

2. 3000 – this is the minimum time in milliseconds that’s required before the location is updated

3. 3.0 – this is the minimum distance in meters

4. the same class that’s calling the method is listening for the LocationChange event

Here is the snippet for the Listener

@Override

public void onLocationChanged(Location newlocation)

{

oldlocation = newlocation;

// logic goes here

}

The LocationListener can be implemented at an Activity Level or it can be implemented as a separate inner  class.

like

private final LocationListener mylocation = new LocationListener() {

@Override

public void onLocationChanged(Location newLocation)

{

oldlocation = newLocation;

//logic goes here

}

GEO CODING: Translating the Address into longitude and latitude .GeoCoder class is used to do this

example :

Method name used ..getFromLocationname()

 String address = "Dallas,Tx"

 GeoCoder geocoder = new GeoCoder(this);

try{

address1 = geocoder.getFromLocationname(address,1);

 if(address1 != null)

{

//create an object in the model called Address

 Address x = address1.get(0);

//logic continues

 }

}Catch(){

}

Reverse GeoCoding: This is quite obvious ..Translating a Location to Address

example:

location = locationManager.getLastKnownLocation(locationprovider);

List<Address> address;

 try

{

// the locale has to be set to english

GeoCoder geocoder = new GeoCoder(this,Locale.ENGLISH);

address = geocoder.getFromLocation(location.getLatitude(),location.getLongitude(),1);

and this returns a list of addresses.

//

Have you ever seen this .Force shut down message on android ..