/**

 * 获取文章第一张图片做为缩略图

 * @param $content

* @return bool|string

*/

private static function thumb($content){

    $contet = stripslashes($content);

    if(preg_match_all("/(src)=(["|‘]?)([^ "‘>]+.(gif|jpg|jpeg|bmp|png))\2/i", $content, $matches)) {

        $str = $matches[3][0];

    $str = substr($str, 6);

            if (preg_match(‘/upload/‘, $str)) {

            return $str;

        }

    }

    return ‘‘;

}