php ci框架验证码实例

<?php  
class Captcha_code 
{ 
    var $width=60; 
    var $num=4; 
    var $height=20; 
    var $name=randcode; 
 
    public function __construct($conf="") 
    { 
        if($conf!="") 
        { 
            foreach($conf as $key=>$value) 
            { 
                $this->$key=$value; 
            } 
        } 
    } 
     
    function show() 
    { 
        Header("Content-type: image/gif"); 
        /* 
        * 初始化 
        */ 
        $border = 0; //是否要边框 1要:0不要 
        $how = $this->num; //验证码位数 
        $w = $this->width; //图片宽度 
        $h = $this->height; //图片高度 
        $fontsize = 5; //字体大小 
        $alpha = "abcdefghijkmnopqrstuvwxyz"; //验证码内容1:字母 
        $number = "023456789"; //验证码内容2:数字 
        $randcode = ""; //验证码字符串初始化 
        srand((double)microtime()*1000000); //初始化随机数种子 
         
        $im = ImageCreate($w, $h); //创建验证图片 
         
        /* 
        * 绘制基本框架 
        */ 
        $bgcolor = ImageColorAllocate($im, 255, 255, 255); //设置背景颜色 
        ImageFill($im, 0, 0, $bgcolor); //填充背景色 
        if($border) 
        { 
            $black = ImageColorAllocate($im, 0, 0, 0); //设置边框颜色 
            ImageRectangle($im, 0, 0, $w-1, $h-1, $black);//绘制边框 
        } 
         
        /* 
        * 逐位产生随机字符 
        */ 
        for($i=0; $i<$how; $i++) 
        {    
            $alpha_or_number = mt_rand(0, 1); //字母还是数字 
            $str = $alpha_or_number ? $alpha : $number; 
            $which = mt_rand(0, strlen($str)-1); //取哪个字符 
            $code = substr($str, $which, 1); //取字符 
            $j = !$i ? 4 : $j+15; //绘字符位置 
            $color3 = ImageColorAllocate($im, mt_rand(0,100), mt_rand(0,100), mt_rand(0,100)); //字符随即颜色 
            ImageChar($im, $fontsize, $j, 3, $code, $color3); //绘字符 
            $randcode .= $code; //逐位加入验证码字符串 
        } 
         
        /* 
        * 添加干扰 
        */ 
        for($i=0; $i<5; $i++)//绘背景干扰线 
        {    
            $color1 = ImageColorAllocate($im, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255)); //干扰线颜色 
            ImageArc($im, mt_rand(-5,$w), mt_rand(-5,$h), mt_rand(20,300), mt_rand(20,200), 55, 44, $color1); //干扰线 
        }    
        for($i=0; $i<$how*15; $i++)//绘背景干扰点 
        {    
            $color2 = ImageColorAllocate($im, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255)); //干扰点颜色  
            ImageSetPixel($im, mt_rand(0,$w), mt_rand(0,$h), $color2); //干扰点 
        } 
         
        //把验证码字符串写入session 
         
        //$this->session->set_userdata(array($this->name=>$randcode)); 
         
        $_SESSION[$this->name]=$randcode; 
        /*绘图结束*/ 
        Imagegif($im); 
        ImageDestroy($im); 
        /*绘图结束*/ 
    } 
} 
?> 

调用php代码：
function verify_image() { 
 
    $conf[name] = verify_code; //作为配置参数 
    $this->load->library(lib_captcha, $conf); 
    $this->lib_captcha->show(); 
    $yzm_session = $this->session->userdata(verify_code); 
    echo $yzm_session; 
} 

html代码：
<dl> 
<dt>验证码：</dt> 
<dd> 
<input type="text" name="verify_text" id="verify_text" class="yzma" value=""> 
<img src="/user/verify_image" alt="验证码" id="verify_code" class="yz_img" /> 
<a href="javascript:changeCode();" class="change_yz">换一张</a> 
</dd> 
<dd class="tips_wrong"><b>验证码不正确</b></dd> 
<dd class="tips_correct"></dd> 
</dl> 

js代码：
function changeCode()
{ 
    FS.query("#verify_code").src ="/user/verify_image?r=" + Math.random(); 
 }