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：

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;
}

private function outFileHeader()
{
  header ("Content-type: image/png");
}

private function createCode()
{
  $this->checkcode = strtoupper(substr(md5(rand()),0,$this->codenum));
}

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
}

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);
  }
}

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。