php图片验证码种

<?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);	}}