PHP 返回随机字符串

public function random($length = 8)
{
    $chars = 'abcdefghijklmnopqrstuvwxyz0123456789';

    $string = '';

    for ($i = 0; $i < $length; $i++) {
        $string .= $chars[mt_rand(0, strlen($chars) - 1)];
    }

    return $string;
}