Thinkphp前后端分离项目图形验证码

font = __DIR__ . '/Elephant.ttf';
        $this->charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789';
        $this->codelen = 4;
        $this->width = 150;
        $this->height = 50;
        $this->fontsize = 20;
        $this->createCode();
    }

    //生成随机码
    private function createCode()
    {
        $_len = strlen($this->charset) - 1;
        for ($i = 0; $i < $this->codelen; ++$i) {
            $this->code .= $this->charset[mt_rand(0, $_len)];
        }
    }

    //生成背景
    private function createBg()
    {
        $this->img = imagecreatetruecolor($this->width, $this->height);
        $color = imagecolorallocate($this->img, mt_rand(157, 255), mt_rand(157, 255), mt_rand(157, 255));
        imagefilledrectangle($this->img, 0, $this->height, $this->width, 0, $color);
    }

    //生成文字
    private function createFont()
    {
        $_x = $this->width / $this->codelen;
        for ($i = 0; $i < $this->codelen; ++$i) {
            $this->fontcolor = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
            imagettftext($this->img, $this->fontsize, mt_rand(-30, 30), $_x * $i + mt_rand(1, 5), $this->height / 1.4, $this->fontcolor, $this->font, $this->code[$i]);
        }
    }

    //生成线条、雪花
    private function createLine()
    {
        //线条
        for ($i = 0; $i < 6; ++$i) {
            $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
            imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $color);
        }
        //雪花
        for ($i = 0; $i < 100; ++$i) {
            $color = imagecolorallocate($this->img, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255));
            imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), '*', $color);
        }
    }


    //对外生成
    public function outImg()
    {
        $this->createBg();
        $this->createLine();
        $this->createFont();
        ob_start();
        // 输出图像
        imagepng($this->img);
        $content = ob_get_clean();
        imagedestroy($this->img);
        return response($content, 200, ['Content-Length' => strlen($content)])->contentType('image/png');
    }


    //返回验证码
    public function getCode()
    {
        return $this->code;
    }

    public function get_captcha(){
        //验证码唯一标识
        $uniqid = uniqid((string)mt_rand(100000, 999999));
        //说明:这里生成的链接其实就是指向验证码显示方法
        $src = url('show','','html',true).'?uniqid='.$uniqid;

        $data = [
            'src' => $src,
            'uniqid' => $uniqid,
        ];

        //这里你们可以根据自己封装的api接口返回方法返回数据
        $this->success('获取成功',$data);
    }
    //显示页面
    public function show($uniqid)
    {
        //存缓存,时间短一点，减少压力
        Cache::set('captcha_' . $uniqid, $this->getCode(), 1200);
        //输出图像
        return $this->outImg();
    }

    /**
     * 验证
     * @param $data
     * @return bool
     */
    public function check($data){
        //从缓存中根据uniqid取验证码
        $code = Cache::get('captcha_' . $data['uniqid']);
        if (!$code) {//没取到说明验证码过期
            $this->error('验证码过期,请刷新后重试');
        }
        //对比缓存中的验证码和表单传递过来的验证码是否相等(大小写不敏感)
        if (strcasecmp($data['code'],$code)!=0) {
            $this->error('验证码错误');
        }
        return true;
    }
}

访问get_captcha方法获得下面的数据

{
	"code": 1,
	"msg": "获取成功",
	"time": "1685612554",
	"data": {
		"src": "http://****.com/api/captcha/show.html?uniqid=8830546478680a5c69b",
		"uniqid": "8830546478680a5c69b"
	}
}

请求src中的url获取验证图片

验证

    public function check_verify(){
        $data['code'] = $this->request->post('code');
        $data['uniqid'] = $this->request->post('uniqid');
        $captcha = new Captcha();
        $captcha->check($data);
    }