很实用的一个php验证码类

<?php

class ImageCode{
 private $width;//验证码图片宽度
 private $height;//验证码图片高度
 private $codeNum;//验证码字符个数
 private $checkCode;//验证码字符
 private $image;//验证码画布
 function __construct($width=60,$height=20,$codeNum=4){
  $this->width=$width;
  $this->height=$height;
  $this->codeNum=$codeNum;
  $this->checkCode=$this->createCheckCode();
 }
 
 function getcreateImage(){
  $this->getcreateImage();
  $this->outputText();
  $this->setDisturbColor();
  $this->outputImage();
 }
 function getCheckCode(){
  return $this->checkCode;
 }
 
 private function getCreateImage(){
  $this->image=imagecreatetruecolor($this->width,$this->height);
  $black=imagecolorallocate($this->image,255,255,255,0);
  $border=imagecolorallocate($this->image,255,255,255,255);
  imagefilledrectangle($this->image,0,0,$this->width-1,$this->height-1,$border);
 }

 private function createCheckCode(){
  for($i=0;$i<$this->codeNum;$i){
   $number=rand(0,2);
   switch($number){
    case 0:
     $rand_number=rand(48,57);//数字
     break;
    case 1:
     $rand_number=rand(65,90);//大写字母
     break;
    case 2:
     $rand_number=rand(97,122);
     break;
   }
   $asc=sprintf("%c",$rand_number);
   $asc_number=$asc_number.$asc;
  }
  return $asc_number;
 }

 private function setDisturbColor(){
  for($i=0;$i<=100;$i++){
   $color=imagecolorallocate($this->image,255,255,255);
   imagesetpixel($this->image,rand(1,$this->width-2),rand(1,$this->height-2),$color);
  }
 }

 private function outputImage(){
  if(imagetypes()&IMG_GIF){
   header("Content_type:image/gif");
   imagegif($this->image);
  }elseif(imagetypes()&IMG_JGP){
   header("Content_type:image/jpeg");
   imagejpeg($this->image,"",0.5);
  }else{
   die("PHP不支持图像创建");
  }
 }

 function __destruct(){
  imagedestroy($this->image);
 }
}

?>