php图片验证码类

[php] 
<?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); 
        } 
    } 
    

补充：Web开发 , php ,

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