php图片验证码类

<?php/** * 图片验证码类 * 生成图片类型验证码，验证码包含数字和大写字母，session中存放md5加密后的验证码 *  * 使用方法： * $captcha = new Catpcha(); * $captcha->buildAndExportImage(); *  * 作          者: luojing * 创建时间: 2013-3-27 上午11:42:12 */class Captcha {private $width;//宽度private $height; //高度private $codeNum;//验证码字符数量private $image;//验证码图像资源private $sessionKey;//session中保存的名字private $captcha;//验证码字符串const charWidth = 10;//单个字符宽度,根据输出字符大小而变/** * 创建验证码类，初始化相关参数 * @param  $width 图片宽度 * @param  $height 图片高度 * @param  $codeNum 验证码字符数量 * @param  $sessionKey session中保存的名字 */function __construct($width = 50, $height = 20, $codeNum = 4, $sessionKey = 'captcha') {$this->width = $width;$this->height = $height;$this->codeNum = $codeNum;$this->sessionKey = $sessionKey;//保证最小高度和宽度if($height < 20) {$this->height = 20;}if($width < ($codeNum * self::charWidth + 10)) {//左右各保留5像素空隙$this->width = $codeNum * self::charWidth + 10;}}/** * 构造并输出验证码图片 */public  function buildAndExportImage() {$this->createImage();$this->setDisturb();$this->setCaptcha();$this->exportImage();}/** * 构造图像，设置底色 */private function createImage() {//创建图像$this->image = imagecreatetruecolor($this->width, $this->height);  //创建背景色$bg = imagecolorallocate($this->image, mt_rand(220, 255), mt_rand(220, 255), mt_rand(220, 255));  //填充背景色imagefilledrectangle($this->image, 0, 0, $this->width - 1, $this->height - 1, $bg);}/** * 设置干扰元素 */private function setDisturb() {//设置干扰点for($i = 0; $i < 150; $i++) {$color = imagecolorallocate($this->image, mt_rand(150, 200),  mt_rand(150, 200),  mt_rand(150, 200));imagesetpixel($this->image, mt_rand(5, $this->width - 10), mt_rand(5, $this->height - 3), $color);}//设置干扰线for($i = 0; $i < 10; $i++) {$color = imagecolorallocate($this->image, mt_rand(150, 220), mt_rand(150, 220), mt_rand(150, 220));imagearc($this->image, mt_rand(-10, $this->width), mt_rand(-10, $this->height), mt_rand(30, 300), mt_rand(20, 200), 55, 44, $color);}//创建边框色$border = imagecolorallocate($this->image, mt_rand(0, 50), mt_rand(0, 50), mt_rand(0, 50));//画边框imagerectangle($this->image, 0, 0, $this->width - 1, $this->height - 1, $border);}/** * 产生并绘制验证码 */private function setCaptcha() {$str = '23456789ABCDEFGHJKLMNPQRSTUVWXYZ';//生成验证码字符for($i = 0; $i < $this->codeNum; $i++) {$this->captcha .= $str{mt_rand(0, strlen($str) - 1)};}//绘制验证码for($i = 0; $i < strlen($this->captcha); $i++) {$color = imagecolorallocate($this->image, mt_rand(0, 200), mt_rand(0, 200), mt_rand(0, 200));$x = floor(($this->width - 10)/$this->codeNum);$x = $x*$i + floor(($x-self::charWidth)/2) + 5;$y = mt_rand(2, $this->height - 20);imagechar($this->image, 5, $x, $y, $this->captcha{$i}, $color);}}/* * 输出图像,验证码保存到session中 */private function exportImage() {if(imagetypes() & IMG_GIF){header('Content-type:image/gif');imagegif($this->image);} else if(imagetypes() & IMG_PNG){header('Content-type:image/png');           imagepng($this->iamge);} else if(imagetypes() & IMG_JPEG) {header('Content-type:image/jpeg');           imagepng($this->iamge);} else {imagedestroy($this->image);die("Don't support image type!");}//将验证码信息保存到session中，md5加密if(!isset($_SESSION)){    session_start();} $_SESSION[$this->sessionKey] = md5($this->captcha);        imagedestroy($this->image);  }function __destruct() {unset($this->width, $this->height, $this->codeNum,$this->captcha);}}