php验证码类

<?php
/**
* @file
* @version  1.0
* @author   网海浪子
* @date  2006-3-30
* @email sxf02615@163.com
* @brief    验证码文件类
*
*/
?>
<?php
class CCheckCodeFile
{
 //验证码位数
 private $mCheckCodeNum  = 4;

 //产生的验证码
 private $mCheckCode   = '';
 
 //验证码的图片
 private $mCheckImage  = '';

 //干扰像素
 private $mDisturbColor  = '';

 //验证码的图片宽度
 private $mCheckImageWidth = '80';

 //验证码的图片宽度
 private $mCheckImageHeight  = '20';

 /**
 *
 * @brief  输出头
 *
 */
 private function OutFileHeader()
 {
  header ("Content-type: image/png");
 }

 /**
 *
 * @brief  产生验证码
 *
 */
 private function CreateCheckCode()
 {
  $this->mCheckCode = strtoupper(substr(md5(rand()),0,$this->mCheckCodeNum));
  return $this->mCheckCode;
 }

 /**
 *
 * @brief  产生验证码图片
 *
 */
 private function CreateImage()
 {
  $this->mCheckImage = @imagecreate ($this->mCheckImageWidth,$this->mCheckImageHeight);
  imagecolorallocate ($this->mCheckImage, 200, 200, 200);
  return $this->mCheckImage;
 }

 /**
 *
 * @brief  设置图片的干扰像素
 *
 */
 private function SetDisturbColor()
 {
  for ($i=0;$i<=128;$i++)
  {
   $this->mDisturbColor = imagecolorallocate ($this->mCheckImage, rand(0,255), rand(0,255), rand(0,255));
   imagesetpixel($this->mCheckImage,rand(2,128),rand(2,38),$this->mDisturbColor);
  }
 }

 /**
 *
 * @brief  设置验证码图片的大小
 *
 * @param  $width  宽
 *
 * @param  $height 高
 *
 */
 public function SetCheckImageWH($width,$height)
 {
  if($width==''||$height=='')return false;
  $this->mCheckImageWidth  = $width;
  $this->mCheckImageHeight = $height;
  return true;
 }

 /**
 *
 * @brief  在验证码图片上逐个画上验证码
 *
 */
 private function WriteCheckCodeToImage()
 {
  for ($i=0;$i<=$this->mCheckCodeNum;$i++)
  {
   $bg_color = imagecolorallocate ($this->mCheckImage, rand(0,255), rand(0,128), rand(0,255));
   $x = floor($this->mCheckImageWidth/$this->mCheckCodeNum)*$i;
   $y = rand(0,$this->mCheckImageHeight-15);
   imagechar ($this->mCheckImage, 5, $x, $y, $this->mCheckCode[$i], $bg_color);
  }
 }

 /**
 *
 * @brief  输出验证码图片
 *
 */
 public function OutCheckImage()
 {
  $this ->OutFileHeader();
  $this ->CreateCheckCode();
  $this ->CreateImage();
  $this ->SetDisturbColor();
  $this ->WriteCheckCodeToImage();
  imagepng($this->mCheckImage);
  imagedestroy($this->mCheckImage);
 }
}
$c_check_code_image = new CCheckCodeFile();
//$c_check_code_image ->SetCheckImageWH(100,50);//设置显示验证码图片的尺寸
$c_check_code_image ->OutCheckImage();
?>

itlearner注：能产生随机的英文字母和数字，不错!