使用PHP将相对路径转换成绝对URL

function rel2abs($rel, $base){        if (parse_url($rel, PHP_URL_SCHEME) != '') return $rel;        if ($rel[0]=='#' || $rel[0]=='?') return $base.$rel;        extract(parse_url($base));        $path = preg_replace('#/[^/]*$#', '', $path);        if ($rel[0] == '/') $path = '';        $abs = "$host$path/$rel";        $re = array('#(/.?/)#', '#/(?!..)[^/]+/../#');    for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}        return $scheme.'://'.$abs;}