读取图片字节大小

    //获取图片大小
    public function getimgweight(){

        $url = 'http://cdn.caomall.net/1536240025614144138.jpeg';
        $len = $this->getUriLen($url);
        echo $len;exit;
    }

    function getUriLen($uri,$user='',$pw='')
    {
        ob_start();

        $ch = curl_init($uri);
        curl_setopt($ch, CURLOPT_HEADER, 1);
        curl_setopt($ch, CURLOPT_NOBODY, 1);  //nobody是关键
        if (!empty($user) && !empty($pw))
        {
            $headers = array('Authorization: Basic ' . base64_encode($user.':'.$pw));
            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        }
        $okay = curl_exec($ch);
        curl_close($ch);

        $head = ob_get_contents();
        ob_end_clean();

        $regex = '/Content-Length:\s+(.+)/';
        preg_match($regex, $head, $matches);

//        print_r("<pre>");
//        print_r ($head);
//        print_r ($matches);
//        print_r("</pre>");

        return $matches[1];
    }