simple 控制器中/**     * 生成验证码     * @param viod     */    public function verify()    {        $captcha = new \think\captcha\Captcha();        $captcha->fontSize = 20;        $captcha->length   = 4;        $captcha->codeSet = '0123456789';        $captcha->useNoise = false;        return $captcha->entry();    }