php验证码类

<?php
/**
* Created by JetBrains PhpStorm.
* User: 张华
* Date: 14-3-8
* Time: 下午12:21
* QQ: 746502560@qq.com
* To change this template use File | Settings | File Templates.
*/
final class Captcha
{
private $width;
private $height;
private $codeNum;
private $code;
private $im;

public  function __construct($width=80, $height=35, $codeNum=4)
{
$this->width = $width;
$this->height = $height;
$this->codeNum = $codeNum;
}

function showImg()
{
//创建图片
$this->createImg();
//设置干扰元素
$this->setDisturb();
//设置验证码
$this->setCaptcha();
//输出图片
$this->outputImg();
}

public  function  checkCaptcha($captchaVal){
$codeNum=httpRequest::getSession('codeNum');
if($codeNum == $captchaVal){
return true;
}
return false;
}

public  function getCaptcha()
{
return $this->code;
}

private function createImg()
{
$this->im = imagecreatetruecolor($this->width, $this->height);
$bgColor = imagecolorallocate($this->im, 255, 255, 255);
imagefill($this->im, 0, 0, $bgColor);
unset($bgColor);
}

private function setDisturb()
{
$area = ($this->width * $this->height) / 20;
$disturbNum = ($area > 250) ? 250 : $area;
//加入弧线
for ($i = 0; $i <= 5; $i++) {
$color = imagecolorallocate($this->im, rand(128, 255), rand(125, 255), rand(100, 255));
imagearc($this->im, rand(0, $this->width), rand(0, $this->height), rand(30, 300), rand(20, 200), 50, 30, $color);
}
unset($area,$disturbNum,$color);
}

private function createCode()
{
$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";

for ($i = 0; $i < $this->codeNum; $i++) {
$this->code .= $str{rand(0, strlen($str) - 1)};
}
httpRequest::setSession('codeNum',$this->code);
unset($str,$i);
}

private function setCaptcha()
{
$this->createCode();
for ($i = 0; $i < $this->codeNum; $i++) {
$color = imagecolorallocate($this->im, rand(0, 250), rand(0, 250), rand(0, 250));
$size = rand(14, 20);
$x = floor($this->width / $this->codeNum) * $i + 5;
$y = rand(0, $this->height - 20);
imagechar($this->im, $size, $x, $y, $this->code{$i}, $color);
}
unset($color,$size,$x,$y,$i);
}

private function outputImg()
{
if (imagetypes() & IMG_JPG) {
header('Content-type:image/jpeg');
imagejpeg($this->im);
imagedestroy($this->im);
} elseif (imagetypes() & IMG_GIF) {
header('Content-type: image/gif');
imagegif($this->im);
imagedestroy($this->im);
} elseif (imagetype() & IMG_PNG) {
header('Content-type: image/png');
imagepng($this->im);
imagedestroy($this->im);
} else {
die("没有你需要的图像资源类型!");
}
}
public function __destruct(){
$this->width=null;
$this->height=null;
$this->codeNum=null;
$this->code=null;
$this->im=null;
unset($this->width,$this->height,$this->codeNum,$this->code);
}

}