php实现点击可刷新验证码

 width=$width; $this->height=$height; $this->codenum=$codenum; } function outImg() { //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); } 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->hei<span style="color:transparent">来源gaodai#ma#com搞*代#码网</span>ght); $back = imagecolorallocate($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 ($i=0;$idisturbColor = 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;$icodenum;$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, $y, $this->checkcode[$i], $bg_color); } } function __destruct() { unset($this->width,$this->height,$this->codenum); } } ?> 

 outImg(); $_SESSION['validationcode'] = $image->checkcode; //存贮验证码到 $_SESSION 中 ?>

 ?php session_start(); $test = $_POST['test']; $test = strtoupper(trim($test)); $submit = $_POST['submit']; if(isset($submit)){ if($test==$_SESSION['validationcode']){ echo 'true'; } else { echo 'false'; } } ?>   <title>Image</title>  <br />