验证码

captcha.php

<?php

/**
 * @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);
  }
}
?>

引入类 yanzhengma.php

<?php 
require_once('captcha.php');
$image =  new Captcha();
$image ->create();

<?php 
ob_start();
session_start();
if(!empty($_POST)){
    $answer = $_POST['answer'];
    $captcha = $_SESSION['captcha_code'];
    if($answer !== $captcha){
        echo "<script>alert('验证码错误');history.go(-1);</script>";
        die;
    }



?>


<form name="login1" method="post" action=" " onsubmit="return checklogin1();">            
            <ul class="loginRegist" style="margin-top: 85px;">
                <li>
                    <span class="titleOne" style=""> 
                        <label for="username">账户</label>
                    </span>
                    <span style=" 200px;position: relative;" class="titleInput">
                        <input id="username" name="username" class="regUserName" type="text" value="" placeholder="" />
                    </span>
                
                </li>               
                <li>
                    <span class="titleOne" style="">
                        <label for="password">密码</label>
                    </span>
                    <span class="titleInput" style="position: relative;">
                        <input id="password" name="password"  type="password" placeholder="" maxlength="32" /> 
                    </span>
                    
                </li>
               
                <li>
                    <span class="titleOne"><label for="username">问题验证</label></span>
                    <span style=" 370px;display: inline-block;text-align: left;">
                        <span class="titleInput"><input name="answer" id="answer"  class="codeInput" type="text"/></span>
                        <!-- <a class="msgCodeBindBtnA" style="color: rgb(153, 153, 153);font-size: 13px;">23+51=？</a> -->
                        <img src="diaocaptcha.php" alt="验证码" onclick="this.src='diaocaptcha.php?='+Math.random()" />
                    </span>
                </li>               
            </ul>
            <div class="registCue">
                 <input class="regeditButton disagree" type="submit" value="登   陆">
            </div>
</form>