/**
     * @param $serverId jssdk檔案上傳返回的serverId
     * @return string 
     */
    public static function savePicToServer($serverId) {
        $accessToken = self::getToken();
        // 要存在你伺服器哪個位置？
        $savePathFile = '/'.date('YmdHis').'.jpg';
        $targetName = $savePathFile;
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
        $fp = fopen($targetName,'wb');
        curl_setopt($ch,CURLOPT_URL,"http://file.api.weixin.qq.com/cgi-bin/media/get?access_token={$accessToken}&media_id={$serverId}");
        curl_setopt($ch,CURLOPT_FILE,$fp);
        curl_setopt($ch,CURLOPT_HEADER,0);
        curl_exec($ch);
        curl_close($ch);
        fclose($fp);

        return PubCommon::serverDomain() . $savePathFile;
    }
 

curl_setopt($ch,CURLOPT_URL,"http://file.api.weixin.qq.com/cgi-bin/media/get?access_token={$accessToken}&media_id={$serverId}");