How to implement random number and letter verification code in php

PHP implements verification code of random numbers and letters

You can customize the size, quantity, interference items, etc. of the generated verification code text, or you can also customize it. Defines the font for the validation text. . .

Without further ado, let’s go straight to the code:

<?php
Class Captcha{
        private $_fontfile=&#39;&#39;;
        private $_size=36;
        private $_width=200;
        private $_height=100;
        private $_length=4;
        private $_image=null;
        private $_snow=0;
        private $_pixel=0;
        private $_line=0;
    public function __construct($config=array()){
        if(is_array($config)&&count($config)>0){
            if(isset($config[&#39;fontfile&#39;])&&is_file($config[&#39;fontfile&#39;])&&is_readable($config[&#39;fontfile&#39;])){
                $this->_fontfile=$config[&#39;fontfile&#39;];
            }else{
                return false;
            }
            if(isset($config[&#39;size&#39;])&&$config[&#39;size&#39;]>0){
                $this->_size=(int)$config[&#39;size&#39;];
            }
            if(isset($config[&#39;width&#39;])&&$config[&#39;width&#39;]>0){
                $this->_width=(int)$config[&#39;width&#39;];
            }
            if(isset($config[&#39;height&#39;])&&$config[&#39;height&#39;]>0){
                $this->_height=(int)$config[&#39;height&#39;];
            }
            if(isset($config[&#39;length&#39;])&&$config[&#39;length&#39;]>0){
                $this->_length=(int)$config[&#39;length&#39;];
            }
            if(isset($config[&#39;snow&#39;])&&$config[&#39;snow&#39;]>0){
                $this->_snow=(int)$config[&#39;snow&#39;];
            }
            if(isset($config[&#39;pixel&#39;])&&$config[&#39;pixel&#39;]>0){
                $this->_pixel=(int)$config[&#39;pixel&#39;];
            }
            if(isset($config[&#39;line&#39;])&&$config[&#39;line&#39;]>0){
                $this->_line=(int)$config[&#39;line&#39;];
            }
            $this->_image=imagecreatetruecolor($this->_width,$this->_height);
            return $this->_image;

         }
         else{
            return false;
        }
    }
    public function getCaptcha(){
        $white=imagecolorallocate($this->_image,255,255,255);
        imagefilledrectangle($this->_image,0,0,$this->_width,$this->_height,$white);
        $str=$this->_generateStr($this->_length);
        if(false===$str){
            return false;
        }
        $fontfile=$this->_fontfile;
        for($i=0;$i<$this->_length;$i++){
            $size=$this->_size;
            $angle=mt_rand(-30,30);
            $x=ceil($this->_width/$this->_length)*$i+mt_rand(5,10);
            $y=ceil($this->_height/1.5);
            $color=$this->_getRandColor();
            //针对中文字符截取
            //$text=mb_substr($str,$i,1,&#39;utf-8&#39;);
            $text=$str{$i};
            imagettftext($this->_image, $size, $angle, $x, $y, $color, $fontfile, $text);
        }
        if($this->_snow){
            $this->_getSnow();

        }else{
            if($this->_pixel){
                $this->_getPixel();

            }
            if($this->_line){
                $this->_getLine();
            }
        }
        header(&#39;content-type:image/png&#39;);
        imagepng($this->_image);
        imagedestroy($this->_image);
        return strtolower($str);
    }
    private function _getSnow(){
        for($i=1;$i<=$this->_snow;$i++){
            imagestring($this->_image,mt_rand(1,5),mt_rand(0,$this->_width),mt_rand(0,$this->_height),&#39;*&#39;,$this->_getRandColor());
        }
    }
    private function _getPixel(){
        for($i=1;$i<=$this->_pixel;$i++){
            imagesetpixel($this->_image,mt_rand(0,$this->_width),mt_rand(0,$this->_height),$this->_getRandColor());
        }
    }
    private function _getLine(){
        for($i=1;$i<=$this->_line;$i++){
            imageline($this->_image,mt_rand(0,$this->_width),mt_rand(0,$this->_height),mt_rand(0,$this->_width),mt_rand(0,$this->_height),$this->_getRandColor());

        }
    }
    private function _generateStr($length=4){
        if($length<1 || $length>30){
            return false;
        }
        $chars=array(
            &#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;,&#39;e&#39;,&#39;f&#39;,&#39;g&#39;,&#39;h&#39;,&#39;k&#39;,&#39;m&#39;,&#39;n&#39;,&#39;p&#39;,&#39;x&#39;,&#39;y&#39;,&#39;z&#39;,
            &#39;A&#39;,&#39;B&#39;,&#39;C&#39;,&#39;D&#39;,&#39;E&#39;,&#39;F&#39;,&#39;G&#39;,&#39;H&#39;,&#39;K&#39;,&#39;M&#39;,&#39;N&#39;,&#39;P&#39;,&#39;X&#39;,&#39;Y&#39;,&#39;Z&#39;,
            1,2,3,4,5,6,7,8,9
            );
        $str=join(&#39;&#39;,array_rand(array_flip($chars),$length));
        return $str;
    }
    private function _getRandColor(){
        return imagecolorallocate($this->_image,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
    }
}
?>

2. testCaptcha.php

<?php
require_once &#39;classgd.class.php&#39;;
$config=array(
&#39;fontfile&#39;=>&#39;fonts/simfang.ttf&#39;,   //引入字体文件
//&#39;snow&#39;=>50,
&#39;pixel&#39;=>100,
&#39;line&#39;=>10
    );
$captcha=new Captcha($config);
$captcha->getCaptcha();
?>

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