本文實例為大家分享了一個實用的php驗證碼類，供大家參考，具體內(nèi)容如下

//驗證碼類
class ValidateCode {
     private $charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789';//隨機因子
     private $code;//驗證碼
     private $codelen = 4;//驗證碼長度
     private $width = 130;//寬度
     private $height = 50;//高度
     private $img;//圖形資源句柄
     private $font;//指定的字體
     private $fontsize = 20;//指定字體大小
     private $fontcolor;//指定字體顏色
     //構(gòu)造方法初始化
     public function __construct() {
        $this->font = dirname(__FILE__).'/font/elephant.ttf';//注意字體路徑要寫對，否則顯示不了圖片
     }
     //生成隨機碼
     private function createCode() {
         $_len = strlen($this->charset)-1;
         for ($i=0;$i<$this->codelen;$i++) {
             $this->code .= $this->charset[mt_rand(0,$_len)];
         }
     }
     //生成背景
     private function createBg() {
         $this->img = imagecreatetruecolor($this->width, $this->height);
         $color = imagecolorallocate($this->img, mt_rand(157,255), mt_rand(157,255), mt_rand(157,255));
         imagefilledrectangle($this->img,0,$this->height,$this->width,0,$color);
     }
     //生成文字
     private function createFont() {
         $_x = $this->width / $this->codelen;
         for ($i=0;$i<$this->codelen;$i++) {
            $this->fontcolor = imagecolorallocate($this->img,mt_rand(0,156),mt_rand(0,156),mt_rand(0,156));
            imagettftext($this->img,$this->fontsize,mt_rand(-30,30),$_x*$i+mt_rand(1,5),$this->height / 1.4,$this->fontcolor,$this->font,$this->code[$i]);
         }
     }
     //生成線條、雪花
     private function createLine() {
         //線條
         for ($i=0;$i<6;$i++) {
            $color = imagecolorallocate($this->img,mt_rand(0,156),mt_rand(0,156),mt_rand(0,156));
            imageline($this->img,mt_rand(0,$this->width),mt_rand(0,$this->height),mt_rand(0,$this->width),mt_rand(0,$this->height),$color);
         }
         //雪花
         for ($i=0;$i<100;$i++) {
            $color = imagecolorallocate($this->img,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255));
            imagestring($this->img,mt_rand(1,5),mt_rand(0,$this->width),mt_rand(0,$this->height),'*',$color);
         }
     }
     //輸出
     private function outPut() {
         header('Content-type:image/png');
         imagepng($this->img);
         imagedestroy($this->img);
     }
     //對外生成
     public function doimg() {
         $this->createBg();
         $this->createCode();
         $this->createLine();
         $this->createFont();
         $this->outPut();
     }
     //獲取驗證碼
     public function getCode() {
        return strtolower($this->code);
     }
}

使用方法：

1、先把驗證碼類保存為一個名為 ValidateCode.class.php 的文件；

2、新建一個名為 captcha.php 的文件進行調(diào)用該類；

captcha.php

session_start();
require './ValidateCode.class.php'; //先把類包含進來，實際路徑根據(jù)實際情況進行修改。
$_vc = new ValidateCode(); //實例化一個對象
$_vc->doimg();
$_SESSION['authnum_session'] = $_vc->getCode();//驗證碼保存到SESSION中

html部分代碼如下

<div class="control-group">
    <label class="control-label">驗證碼：</label>
    <div class="controls">
       <input type="text" name="validate" value="" style="width:10%">
       <img id="verify_img" src="captcha.php" alt="驗證碼" onclick="refreshVerify()">
       <a href="javascript:refreshVerify()">點擊刷新</a>
       <script>
            function refreshVerify() {
                var ts = Date.parse(new Date())/1000;
                var img = document.getElementById('verify_img');
                img.src = "captcha.php?id="+ts;
            }
        </script>
    </div>
</div>

驗證部分可以這樣寫：

session_start();
if($_SESSION['authnum_session']!=strtolower(trim($_POST['validate'])))
{
        echo '驗證碼錯誤請重新輸入！';
        exit;
}