PHP实现简单实用的验证码类

本文实例讲述了PHP实现简单实用的验证码类。分享给大家供大家参考。具体如下：

    <?php
    /**
    * @version 1.0
    * @author  bolted snail
    * @date 2011-10-15
    * @PHP验证码类
    * 使用方法：
    * $image=new Captcha();
    * $image->config('宽度','高度','字符个数','验证码session索引');
    * $image->create();//这样就会向浏览器输出一张图片
    * //所有参数都可以省略，
    * 默认是：宽80 高20 字符数4 验证码session索引captcha_code
    * 第四个参数即把验证码存到$_SESSION['captcha_code']
    * 最简单使用示例:
    * $image=new Captcha();
    * $image->create();//这样就会向浏览器输出一张图片
    */
    class Captcha
    {
    private $width=80,$height=20,$codenum=4;
    public $checkcode;   //产生的验证码
    private $checkimage;  //验证码图片 
    private $disturbColor = ''; //干扰像素
    private $session_flag='captcha_code';//存到session中的索引
    //尝试开始session
    function __construct(){
      @session_start();
    }
    /*
    * 参数：（宽度，高度，字符个数）
    */
    function config($width='80',$height='20',$codenum='4',$session_flag='captcha_code')
    { 
      $this->width=$width;
      $this->height=$height;
      $this->codenum=$codenum;
      $this->session_flag=$session_flag;
    }
    function create()
    {
      //输出头
      $this->outFileHeader();
      //产生验证码
      $this->createCode();
      //产生图片
      $this->createImage();
      //设置干扰像素
      $this->setDisturbColor();
      //往图片上写验证码
      $this->writeCheckCodeToImage();
      imagepng($this->checkimage);
      imagedestroy($this->checkimage);
      $_SESSION[$this->session_flag]=$this->checkcode;
    }
    /*
      * @brief 输出头
      */
    private function outFileHeader()
    {
      header ("Content-type: image/png");
    }
    /**
      * 产生验证码
      */
    private function createCode()
    {
      $this->checkcode = strtoupper(substr(md5(rand()),0,$this->codenum));
    }
    /**
      * 产生验证码图片
      */
    private function createImage()
    {
      $this->checkimage = @imagecreate($this->width,$this->height);
      $back = imagecolorallocate($this->checkimage,255,255,255); 
      $border = imagecolorallocate($this->checkimage,0,0,0); 
      imagefilledrectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$back); // 白色底
      imagerectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$border);  // 黑色边框
    }
    /**
      * 设置图片的干扰像素 
      */
    private function setDisturbColor()
    {
      for ($i=0;$i<=200;$i++)
      {
      $this->disturbColor = imagecolorallocate($this->checkimage, rand(0,255), rand(0,255), rand(0,255));
      imagesetpixel($this->checkimage,rand(2,128),rand(2,38),$this->disturbColor);
      }
    }
    /**
      *
      * 在验证码图片上逐个画上验证码
      *
      */
    private function writeCheckCodeToImage()
    {
      for ($i=0;$i<$this->codenum;$i++)
      {
      $bg_color = imagecolorallocate ($this->checkimage, rand(0,255), rand(0,128), rand(0,255));
      $x = floor($this->width/$this->codenum)*$i;
      $y = rand(0,$this->height-15);
      imagechar ($this->checkimage, rand(5,8), $x+5, $y, $this->checkcode[$i], $bg_color);
      }
    }
    function __destruct()
    {
      unset($this->width,$this->height,$this->codenum,$this->session_flag);
    }
    }
    ?>

希望本文所述对大家的php程序设计有所帮助。