PHP实现简单实用的验证码类_php技巧

<?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);}}?>

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