php 获取当前站点的访问路径根目录

/**
 * 获取当前站点的访问路径根目录
 * @return [type] [description]
 */
function getSiteUrl() {
$uri=$_SERVER['REQUEST_URI']?$_SERVER['REQUEST_URI']:($_SERVER['PHP_SELF']?$_SERVER['PHP_SELF']:$_SERVER['SCRIPT_NAME']);
 return 'http://'.$_SERVER['HTTP_HOST'].substr($uri, 0, strrpos($uri, '/')+1);
}