phpʵÏÖµÄCaptchaÑéÖ¤ÂëÀàʵÀý

±¾ÎÄʵÀý½²ÊoÁËphpʵÏÖµÄCaptchaÑeÖ¤ÂeÀa£¬ÔÚphp³ÌÐoÉe¼ÆÖÐÓÐ׿«Æa¹aºµÄÓ¦Óá£ÖÏi¸ø´o¼Ò¹(C)´o¼Ò²Î¿¼¡£¾ßÌa½¨ÈçÏ£º

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    <?php
    /** Captcha ÑeÖ¤ÂeÀa
    * Date: 2011-02-19
    * Author: fdipzone
    */

    class Captcha{ //class start

     private $sname = '';

     public function __construct($sname=''){ // $sname captcha session name
     $this->sname = $sname==''? 'm_captcha' : $sname;
     }

     /** Éu³ÉÑeÖ¤ÂeͼƬ
     * @param int $length ÑeÖ¤Âe³¤¶È
     * @param Array $param …¢"µ
     * @return IMG
     */
     public function create($length=4,$param=array()){
     Header("Content-type: image/PNG");
     $authnum = $this->random($length); //Éu³ÉÑeÖ¤Âe×Ö*u.

     $width = isset($param['width'])? $param['width'] : 13; //ÎÄ×Ö¿i¶È
     $height = isset($param['height'])? $param['height'] : 18; //ÎÄ×ָ߶È
     $pnum = isset($param['pnum'])? $param['pnum'] : 100; //¸ÉÈÅÏoËظoÊý
     $lnum = isset($param['lnum'])? $param['lnum'] : 2; //¸ÉÈÅÏßÌoÊý

     $this->captcha_session($this->sname,$authnum);  //½«Ëae»uÊýдÈesession

     $pw = $width*$length+10;
     $ph = $height+6;

     $im = imagecreate($pw,$ph);   //imagecreate() н¨Í¼Ïñ£¬´oСΪ x_size ºÍ y_size µÄ¿Õ°×ͼÏñ¡£
     $black = ImageColorAllocate($im, 238,238,238); //ÉeÖñ³¾°ÑÕÉ«

     $values = array(
      mt_rand(0,$pw), mt_rand(0,$ph),
      mt_rand(0,$pw), mt_rand(0,$ph),
      mt_rand(0,$pw), mt_rand(0,$ph),
      mt_rand(0,$pw), mt_rand(0,$ph),
      mt_rand(0,$pw), mt_rand(0,$ph),
      mt_rand(0,$pw), mt_rand(0,$ph)
     );
     imagefilledpolygon($im, $values, 6, ImageColorAllocate($im, mt_rand(170,255),mt_rand(200,255),mt_rand(210,255))); //ÉeÖøÉÈŶa±ßÐε×ͼ

     /* ÎÄ×Ö */
     for ($i = 0; $i < strlen($authnum); $i++){
      $font = ImageColorAllocate($im, mt_rand(0,50),mt_rand(0,150),mt_rand(0,200));//ÉeÖÃÎÄ×ÖÑÕÉ«
      $x = $i/$length * $pw + rand(1, 6); //ÉeÖÃËae»uX×ø±e
      $y = rand(1, $ph/3);   //ÉeÖÃËae»uY×ø±e
      imagestring($im, mt_rand(4,6), $x, $y, substr($authnum,$i,1), $font); 
     }

     /* ¼ÓÈe¸ÉÈÅÏoËØ */
     for($i=0; $i<$pnum; $i++){
      $dist = ImageColorAllocate($im, mt_rand(0,255),mt_rand(0,255),mt_rand(0,255)); //ÉeÖÃÔÓµaÑÕÉ«
      imagesetpixel($im, mt_rand(0,$pw) , mt_rand(0,$ph) , $dist); 
     } 

     /* ¼ÓÈe¸ÉÈÅÏß */
     for($i=0; $i<$lnum; $i++){
      $dist = ImageColorAllocate($im, mt_rand(50,255),mt_rand(150,255),mt_rand(200,255)); //ÉeÖÃÏßÑÕÉ«
      imageline($im,mt_rand(0,$pw),mt_rand(0,$ph),mt_rand(0,$pw),mt_rand(0,$ph),$dist);
     }

     ImagePNG($im); //ÒÔ PNG ¸ñʽ½«Í¼ÏñÊa³oµ½a¯ÀÀÆ÷»oÎļþ
     ImageDestroy($im); //Ïu»ÙһͼÏñ
     }

     /** ¼i²eÑeÖ¤Âe
     * @param String $captcha ÑeÖ¤Âe
     * @param int $flag ÑeÖ¤³É¹¦ºo 0:²»Ça³ýsession 1:Ça³ýsession
     * @return boolean
     */ 
     public function check($captcha,$flag=1){
     if(empty($captcha)){
      return false;
     }else{
      if(strtoupper($captcha)==$this->captcha_session($this->sname)){ //¼i²aÑeÖ¤Âe
      if($flag==1){
       $this->captcha_session($this->sname,'');
      }
      return true;
      }else{
      return false;
      }
     }
     }

     /* ²uÉuËae»uÊýº¯Êý
     * @param int $length ÐeÒªËae»uÉu³ÉµÄ×Ö*u´®"µ
     * @return String
     */
     private function random($length){
     $hash = '';
     $chars = 'ABCDEFGHIJKLMNPQRSTUVWXYZ23456789';
     $max = strlen($chars) - 1;
     for($i = 0; $i < $length; $i++) {
      $hash .= $chars[mt_rand(0, $max)];
     }
     return $hash;
     }

     /** ÑeÖ¤Âesession´¦Ài*½*¨
     * @param String $name captcha session name
     * @param String $value
     * @return String
     */
     private function captcha_session($name,$value=null){
     if(isset($value)){
      if($value!==''){
      $_SESSION[$name] = $value;
      }else{
      unset($_SESSION[$name]);
      }
     }else{
      return isset($_SESSION[$name])? $_SESSION[$name] : '';
     }
     }
    } // class end
    ?>

demoʾÀý³ÌÐoÈçÏ£º

    <?php 
      session_start(); 
      require_once('Captcha.class.php'); 

      $obj = new Captcha($sname);   # ´´½¨CaptchaÀa¶ÔÏo 
                      # $snameΪ±£´aecaptchaµÄsession name,¿ÉÁo¿Õ,Áo¿Õ„tΪ'm_captcha' 

      $obj->create($length,$param);  #´´½¨Captcha²¢Êa³oͼƬ 
                      # $lengthΪCaptcha³¤¶È£¬¿ÉÁo¿Õ£¬Ä¬ÈÏΪ4 
                      /* $param = array( 
                          'width' => 13    captcha ×Ö*u¿i¶È 
                          'height' => 18    captcha ×Ö*u¸ß¶È 
                          'pnum' => 100    ¸ÉÈŵa¸oÊý
                          'lnum' => 2     ¸ÉÈÅÏßÌoÊý 
                          ) 
                          ¿ÉÁo¿Õ 
                      */ 
      $obj->check($captcha,$flag); # ¼i²eÓû§ÊaÈeµÄÑeÖ¤ÂeÊÇ*ñÕýÈ*£¬true or false 
                      # $captchaΪÓû§ÊaÈeµÄÑeÖ¤Âe,±ØÌi 
                      # $flag ¿ÉÁo¿Õ£¬Ä¬ÈÏΪ1  
                      #    1:µ±ÑeÖ¤³É¹¦ºo×Ô¶¯Ça³ýcaptcha session 
                      #    0:µ²ÑeÖ¤³É¹¦ºo²»Ça³ýcaptcha session,ÓÃÓÚajax¼i²e 
    ?>

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