有需要的朋友，参考下吧。

复制代码 代码如下:

<?php

/**

* 仿QQ验证码

*/

//Session保存路径

$sessSavePath = dirname(__FILE__)."/../data/sessions/";

if(is_writeable($sessSavePath) && is_readable($sessSavePath)){ session_save_path($sessSavePath); }

session_start();

//获取随机字符

$rndstring = '';

for($i=0; $i<4; $i++) $rndstring .= chr(mt_rand(65,90));

$img_height=45; //先定义图片的长、宽

$img_width=10;

//如果支持GD，则绘图

if(function_exists("imagecreate"))

{

//Firefox部份情况会多次请求的问题，5秒内刷新页面将不改变session

$ntime = time();

if(empty($_SESSION['dd_ckstr_last']) || empty($_SESSION['dd_ckstr']) || ($ntime - $_SESSION['dd_ckstr_last'] > 5))

{

$_SESSION['dd_ckstr'] = strtolower($rndstring);

$_SESSION['dd_ckstr_last'] = $ntime;

}

$rndstring = $_SESSION['dd_ckstr'];

$rndcodelen = strlen($rndstring);

//创建图片，并设置背景色

$im = imagecreate(46,20);

ImageColorAllocate($im, 240,243,248);

//干扰线

$lineColor1 = ImageColorAllocate($im, mt_rand(174,218),mt_rand(190,225),mt_rand(217,237));

for($j=1;$j<=2;$j=$j+3)

{

imageline($im,0,$j+mt_rand(1,15),48,$j+mt_rand(1,15),$lineColor1);

}

//输出文字

$fontColor = ImageColorAllocate($im, mt_rand(0,150),mt_rand(0,150),mt_rand(0,150));

for($i=0;$i<$rndcodelen;$i++)

{

$bc = mt_rand(0,1);

$rndstring[$i] = strtoupper($rndstring[$i]);

imagestring($im,mt_rand(3,5),$i*$img_height/4+mt_rand(1,5),mt_rand(1,$img_width/2), $rndstring[$i], $fontColor);

}

header("Pragma:no-cache"r"n");

header("Cache-Control:no-cache"r"n");

header("Expires:0"r"n");

//输出特定类型的图片格式，优先级为 gif -> jpg ->png

if(function_exists("imagepng"))

{

header("content-type:image/png"r"n");

imagepng($im);

}

else

{

header("content-type:image/jpeg"r"n");

imagejpeg($im);

}

ImageDestroy($im);

exit();

}

else

{

//不支持GD，只输出字母 ABCD

$_SESSION['dd_ckstr'] = "abcd";

$_SESSION['dd_ckstr_last'] = '';

header("content-type:image/png"r"n");

header("Pragma:no-cache"r"n");

header("Cache-Control:no-cache"r"n");

header("Expires:0"r"n");

$fp = fopen("data/vdcode.jpg","r");

echo fread($fp,filesize("data/vdcode.jpg"));

fclose($fp);

exit();

}

?>