1、实现效果生成验证验证码 

 

 

 

 2、验证码类CaptchaBase.php

<?php
class CaptchaBase
{
    private $width;
    private $height;
    private $length;
    public function __construct($width, $height, $length)
    {
        $this->width = $width;
        $this->height = $height;
        $this->length = $length;
    }
    public function generate()
    {
        $image = imagecreatetruecolor($this->width, $this->height);
        $background_color = imagecolorallocate($image, 255, 255, 255);
        imagefill($image, 0, 0, $background_color);
        $text_color = imagecolorallocate($image, 0, 0, 0);
        $captcha_string = $this->generateRandomString($this->length);
        $_SESSION['captcha'] = $captcha_string;
        imagestring($image, 5, 5, 5, $captcha_string, $text_color);
        header('Content-Type: image/jpeg');
        imagejpeg($image);
        imagedestroy($image);
    }
    private function generateRandomString($length)
    {
        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $random_string = '';
        for ($i = 0; $i < $length; $i++) {
            $random_string .= $characters[rand(0, strlen($characters) - 1)]." ";
        }
        return trim($random_string);
    }
    public function validate($input)
    {
        $captcha= strtolower(preg_replace('/\s+/', '', $_SESSION['captcha']));
        $input= strtolower(preg_replace('/\s+/', '', $input));
        if ($captcha&& $captcha ==$input) { // 将用户输入和保存的验证码都转换为小写形式进行比较
            return true;
        }
        return false;
    }
}

3、封装function.php

function Code(){
     return new CaptchaBase(80, 30, 4);
}

4、使用和验证indexCrl.php

<?php
class indexCrl{
    //生成验证码
    public function index(){
        echo  Code()->generate();
    }
    //验证验证码
    public function validate(){
      if(Code()->validate($_GET['code'])){
         echo '验证成功';
       }else{
          echo '验证失败';
       }
    }
}