For the get method:
private void executeReq(URL urlObject) throws IOException{
    HttpURLConnection conn = null;
    conn = (HttpURLConnection) urlObject.openConnection();
    conn.setReadTimeout(100000); //Milliseconds
    conn.setConnectTimeout(150000); //Milliseconds
    conn.setRequestMethod("GET");
    conn.setDoInput(true);
    // Start connect
    conn.connect();
    String response = convertStreamToString(conn.getInputStream());
    Log.d("Response:", response);
}
You may call it with
try {
    String parameters = ""; //
    URL url = new URL("http://alefon.com" + parameters);
    executeReq(url);
}
catch(Exception e){
    //Error
}
To check Internet connectivity, use:
private void checkInternetConnection() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo ni = cm.getActiveNetworkInfo();
    if (null == ni)
        Toast.makeText(this, "no internet connection", Toast.LENGTH_LONG).show();
    else {
         Toast.makeText(this, "Internet Connect is detected .. check access to sire", Toast.LENGTH_LONG).show();
         //Use the code above...
    }
}