完美的php生成验证码程序代码

时间：2015-01-23 来源：西部数据作者：西部数据

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:

//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 < $characters_on_image) {

$code .= substr($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; $i<$random_dots; $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; $i<$random_lines; $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

//开源代码phpfensi.com

$_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:

<?php

session_start();

if(isset($_REQUEST['Submit'])){

    // code for check server side validation

    if(emptyempty($_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!

    }

}

?>

<style type="text/css">

.table{

    font-family:Arial, Helvetica, sans-serif;

    font-size:12px;

    color:#333;

    background-color:#E4E4E4;

}

.table td{

    background-color:#F8F8F8;

}

</style>

<form action="" method="post" name="form1" id="form1" >

  <table width="400" border="0" align="center" cellpadding="5" cellspacing="1">

<?php if(isset($msg)){?>

    <tr>

      <td colspan="2" align="center" valign="top"><?php echo $msg;?></td>

    </tr>

<?php } ?>

    <tr>

      <td align="right" valign="top"> 验证码Demo:</td>

      <td><img src="captcha_code_file.php?rand=<?php echo rand(0,20);?>" id='captchaimg'  onclick="refreshCaptcha();" ><br>

        <label for='message'>请输入验证码:</label>

        <br>

        <input id="6_letters_code" name="6_letters_code" type="text">

        <br>

        如果看不到，请 <a href='javascript： refreshCaptcha();'>点我</a> 刷新一下!

        </p></td>

    </tr>

    <tr>

      <td> </td>

      <td><input name="Submit" type="submit" onclick="return validate();" value="Submit"></td>

    </tr>

  </table>

</form>

<script type='text/javascript'>

//定义的刷新请求

function refreshCaptcha()

{

    var img = document.images['captchaimg'];

    img.src = img.src.substring(0,img.src.lastIndexOf("?"))+"?rand="+Math.random()*1000;

}

</script>