完美的php生成验证码程序代码

本文章给大家介绍一个非常不错的生成验证码的php程序，首先当用户请求HTTP的时候，服务器端就创建一个唯一的sessionid，这个是session会话ID，然后就去启动GD库或者imagemagick这些画图工具，把程序生成的随机的字符写到一张图片里面，然后显示到客户端,再由用户输入提交数据，然后我们程序把生成验证保存在session中进行比较，这样就完成了验证码的生成与验证了。

•新建一个PHP文件captcha_code_file.php

代码如下

复制代码

//首先开启session session_start(); //定义前台显示验证码长&宽 $image_width = 120; $image_height = 40; $characters_on_image = 6; $font = './monofont.ttf'; //The characters that can be used in the CAPTCHA code. //avoid confusing characters (l 1 and i for example) $possible_letters = '23456789bcdfghjkmnpqrstvwxyz'; $random_dots = 10; $random_lines = 30; $captcha_text_color="0x142864"; $captcha_noice_color = "0x142864"; //定义要生成验证码的字符串 $code = ''; $i = 0; while ($i $code .= substr($possible_letters, mt_rand(0, strlen($possible_letters)-1), 1); $i++; } $font_size = $image_height * 0.75; $image = @imagecreate($image_width, $image_height); /* setting the background, text and noise colours here */ $background_color = imagecolorallocate($image, 255, 255, 255); $arr_text_color = hexrgb($captcha_text_color); $text_color = imagecolorallocate($image, $arr_text_color['red'],         $arr_text_color['green'], $arr_text_color['blue']); $arr_noice_color = hexrgb($captcha_noice_color); $image_noise_color = imagecolorallocate($image, $arr_noice_color['red'],         $arr_noice_color['green'], $arr_noice_color['blue']); /* generating the dots randomly in background */ for( $i=0; $i imagefilledellipse($image, mt_rand(0,$image_width),  mt_rand(0,$image_height), 2, 3, $image_noise_color); } /* generating lines randomly in background of image */ for( $i=0; $i imageline($image, mt_rand(0,$image_width), mt_rand(0,$image_height),  mt_rand(0,$image_width), mt_rand(0,$image_height), $image_noise_color); } /* create a text box and add 6 letters code in it */ $textbox = imagettfbbox($font_size, 0, $font, $code); $x = ($image_width - $textbox[4])/2; $y = ($image_height - $textbox[5])/2; imagettftext($image, $font_size, 0, $x, $y, $text_color, $font , $code); /* Show captcha image in the page html page */ header('Content-Type: image/jpeg');// defining the image type to be shown in browser widow imagejpeg($image);//showing the image imagedestroy($image);//destroying the image instance //设置session，做验证 $_SESSION['6_letters_code'] = $code; function hexrgb ($hexstr) {   $int = hexdec($hexstr);   return array("red" => 0xFF & ($int >> 0x10),                "green" => 0xFF & ($int >> 0x8),                "blue" => 0xFF & $int); }

调用页面显示验证码页面index.php

 代码如下

复制代码

session_start();
if(isset($_REQUEST['Submit'])){
    // code for check server side validation
    if(empty($_SESSION['6_letters_code'] ) ||
        strcasecmp($_SESSION['6_letters_code'], $_POST['6_letters_code']) != 0)
    { 
        $msg="您输入的验证码有误，请重新输入!";
    }else{
        echo "您输入的是正确的!";
        // Captcha verification is Correct. Final Code Execute here!
    }
}   
 ?>

 

   
     
   

   
     
     
   
   
     
     
   
 

验证码Demo:	请输入验证码:                                 如果看不到，请 点我 刷新一下!