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：
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<?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 $session_flag='captcha_code';//存到session中的索引
//尝试开始session
function __construct(){
@session_start();
}
/*
* 参数：（宽度，高度，字符个数）
*/
function config($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);
}
}
?>
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希望本文所述对大家的php程序设计有所帮助。