arka planda sürekli çalışan wifi kontrolü ...

Wifi ve network durumu değiştiğinde yayınlanan BroadcastReceiver  işine yarar.http://stackoverflow.com/questions/10733121/broadcastreceiver-when-wifi-or-3g-network-state-changed

public class WifiReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {     
        ConnectivityManager conMan = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 
        NetworkInfo netInfo = conMan.getActiveNetworkInfo();
        if (netInfo != null && netInfo.getType() == ConnectivityManager.TYPE_WIFI) 
            Log.d("WifiReceiver", "wifi baglantisi mevcut);
        else
            Log.d("WifiReceiver", "wifi bağlantısı yok");    
    }   
};

manifest

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<receiver android:name=".WifiReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
    </intent-filter>
</receiver>