joomla2.5 判断当前语言是不是默认语言

$lang_tag = JFactory::getLanguage()->getTag();
$lang_params = JComponentHelper::getParams('com_languages');
$default_lang = $lang_params->get('site');
if($langTag == $default_lang){
//是默认语言
}else{
//不是默认语言
}