NetworkButton.java

public class NetworkButton extends Button {

    // See Otto's sample application for how BusProvider works. Any mechanism
    // for getting a singleton instance will work.
    Bus bus = BusProvider.get();

    public NetworkButton(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public NetworkButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        bus.register(this);
    }

    @Override
    protected void onDetachedFromWindow() {
        bus.unregister(this);
        super.onDetachedFromWindow();
    }

    @Subscribe
    public void onNetworkStatusUpdated(NetworkStatus status) {
        setEnabled(status.isConnected());
    }
}

NetworkStatusProducerApplication.java

public class NetworkStatusProducerApplication extends Application {

    Bus bus = BusProvider.get();

    NetworkStatus networkStatus;

    @Override
    public void onCreate() {
        super.onCreate();
        updateNetworkStatus();
        bus.register(this);
    }

    public void updateNetworkStatus() {
        final ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        final android.net.NetworkInfo wifi = connMgr
                .getNetworkInfo(ConnectivityManager.TYPE_WIFI);

        final android.net.NetworkInfo mobile = connMgr
                .getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

        boolean wifiConnected = wifi.isAvailable()
                && wifi.getState() == NetworkInfo.State.CONNECTED;

        boolean mobileConnected = mobile.isAvailable()
                && mobile.getState() == NetworkInfo.State.CONNECTED;

        boolean isConnected = wifiConnected || mobileConnected;

        networkStatus = new NetworkStatus(isConnected);

        bus.post(produceNetworkStatus());
    }

    @Produce
    public NetworkStatus produceNetworkStatus() {
        return networkStatus;
    }
    
    public static class NetworkStatus {

        private final boolean connected;

        public NetworkStatus(boolean connected) {
            this.connected = connected;
        }

        public boolean isConnected() {
            return connected;
        }
    }
}

NetworkStatusReceiver.java

public class NetworkStatusReceiver extends BroadcastReceiver {
    
    /** register this receiver with the intents:
     *  <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
     *  <action android:name="android.net.wifi.WIFI_STATE_CHANGED"/>
     */   

    @Override
    public void onReceive(final Context context, final Intent intent) {
        ((NetworkStatusProducerApplication) context.getApplicationContext()).updateNetworkStatus();
    }
}