完美的php生成验证码程序代码-php手册-PHP中文网

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 < $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
$_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!
}
}
?>