php仿QQ验证码的实例分析

有需要的朋友，参考下吧。


复制代码 代码如下:

<?php

/**

* 仿qq验证码

*/

//ssion保存路径

$sssavepath = dirname(__file__).”/../data/ssions/”;

if(is_writeable($sssavepath) && is_readable($sssavepath)){ ssion_save_path($sssavepath); }

ssion_start();
口算题二年级
//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，则齐襄王绘图

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ssion

$ntime = time();

if(empty($_ssion[‘dd_ckstr_last’]) || empty($_ssion[‘dd_ckstr’]) || ($ntime – $_ssion[‘dd_ckstr_last’] > 5))

{

$_ssion[‘dd_ckstr’] = str论语是一部什么著作tolower($rndstring);

$_ssion[‘dd_ckstr_last’] = $ntime;

}

$rndstring = $_ssion[‘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);

}

el

{

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

imagejpeg($im);

}

imagedestroy($im);

exit();

}

el

{

//不支持gd，只输出字母 abcd

$_ssion[‘dd_ckstr’] = “abcd”;

$_ssion[‘dd_ckstr_last’] = ”;

header(“content-type:image/png”r&#跳跳兔8221;n”);

header(“pragma:no-cache”r”n”);

header(“cache-control:no-cache”r”n”);

header(“expires:流水对0″r”n”);

$fp = fopen(“data/vdcode.jpg”,”r”);

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

fclo($fp);

exit();

}

?>