PHP封装的验证码工具类定义与用法示例

//验证码宽度
private $width;
//验证码高度
private $height;
//验证的个数
private $length;
//干扰点个数
private $dots;
//干扰点的类型
private $type;
//干扰线个数
private $lines;
//文字
private $font;

<?php
//创建验证码工具类
class captcha {
 //验证码的各种参数
 //验证码宽度
 private $width;
 //验证码高度
 private $height;
 //验证的个数
 private $length;
 //干扰点个数
 private $dots;
 //干扰点的类型
 private $type;
 //干扰线个数
 private $lines;
 //文字
 private $font;
 //验证码属性的构造方法
 public function __construct($arr = array ()) {
  //将属性赋值
  $this->width = isset ($arr['width']) ? trim($arr['width']) : '270';
  $this->height = isset ($arr['height']) ? trim($arr['height']) : '30';
  $this->length = isset ($arr['length']) ? trim($arr['length']) : '4';
  $this->dots = isset ($arr['dots']) ? trim($arr['dots']) : '81';
  $this->type = isset ($arr['type']) ? trim($arr['type']) : '';
  $this->lines = isset ($arr['lines']) ? trim($arr['lines']) : '5';
  $this->font = isset ($arr['font']) ? trim($arr['font']) : './cambriab.ttf';
 }
 //创建验证码的方法
 public function captcha() {
  //创建画布
  $img = imagecreatetruecolor($this->width, $this->height);
  //填充颜色
  //颜色资源
  $color = imagecolorallocate($img, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255));
  //填充背景
  imagefill($img, 0, 0, $color);
  //添加干扰点
  for ($i = 0; $i < $this->dots; $i++) {
   //颜色资源
   $dots_color = imagecolorallocate($img, mt_rand(150, 200), mt_rand(150, 200), mt_rand(150, 200));
   //插入干扰点
   imagestring($img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), $this->type, $dots_color);
  }
  //添加干扰线
  for ($i = 0; $i < $this->lines; $i++) {
   //颜色资源
   $line_color = imagecolorallocate($img, mt_rand(150, 200), mt_rand(150, 200), mt_rand(150, 200));
   //插入干扰线
   imageline($img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $line_color);
  }
  //获取验证码，然后插入验证文字
  //文字高度
  $size = mt_rand(18, 20);
  //获取验证码
  $str = $this->captchastring();
  for ($i = 0; $i < strlen($str); $i++) {
   //颜色资源
   $str_color = imagecolorallocate($img, mt_rand(50, 150), mt_rand(50, 150), mt_rand(50, 150));
   //插入验证码
   imagettftext($img, $size, mt_rand(-45, 45), $this->width / ($this->length + 2)  ($i +1), (($this->height - $size) / 2) + $size, $str_color, $this->font, $str[$i]);
  }
  //将得到的验证码存入SESSION中，便于以后的验证码判断
  @ session_start();
  $_SESSION['captcha'] = $str;
  //输出图片
  header("content-type:image/png");
  imagepng($img);
  //清除资源
  imagedestroy($img);
 }
 //获取随机的验证内容:A-Z,a-z,1-9
 private function captchaString() {
  //获取四个随机的字符串
  $str = "";
  for ($i = 0; $i < $this->length; $i++) {
   switch (mt_rand(1, 3)) {
    case 1 :
     $str .= chr(mt_rand(49, 57));
     break;
    case 2 :
     $str .= chr(mt_rand(97, 122));
     break;
    case 3 :
     $str .= chr(mt_rand(65, 90));
     break;
   }
  }
  return $str;
 }
 //判断验证码
 public static function checkCaptcha($captcha) {
  @ session_start();
  return strtoupper($captcha) === strtoupper($_SESSION['captcha']);
 }
}
//使用方法
$img = new captcha();//这里采用默认参数
$img->captcha();
?>