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 $session_flag='captcha_code';//存到session中的索引//尝试开始sessionfunction __construct(){ @session_start();}/** 参数：（宽度，高度，字符个数）*/function config($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。