一个好用的PHP验证码类实例分享

分享一个好用的php验证码类，包括调用示例。
说明：
如果不适用指定的字体，那么就用imagestring()函数，如果需要遇到指定的字体，就要用到imagettftext()函数。字体的位置在c盘下windows/fonts.

参考了网上的php 生成验证码的方法，以及php 图片验证码和php 中文验证码的生成方法。用到了php gd库的相关知识。

1，生成验证码的类 verificationcode.class.php

<?php 
    class verificationcode{ 
        private $charset="abcdefghjkmnpqrstuvwxyzabcdefghjkmnpqrstuvwxyz23456789";  //随机因子 
        private $code;  //验证码 
        private $codelen=4; //验证码长度 
        private $width=110; //宽度 
        private $height=30; //高度 
        private $img;   //图像资源句柄 
        private $font;  //制定字体 
        private $fontsize=25;   //字体大小 
        private $fontcolor; //字体颜色 
        public function __construct(){ 
            $this->font="calibriz.ttf"; 
        } 
        //生成验证码 
        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),$i*$x+mt_rand(1,5),$this->height/1.4,$this->fontcolor,$this->font,$this->code[$i]);  // www.jb51.net
                //imagestring($this->img,5,$i*$x+mt_rand(1,5),5,$this->code[$i],$this->fontcolor); 
            } 
        } 
        //生成线条、雪花 
        private function createdisturb(){ 
            for ($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,$this->width),mt_rand(0,$this->width),mt_rand(0,$this->width),$color); 
            } 
            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); 
            } 
        } 
        //输出 
        private function output(){ 
            header("content-type:image/png"); 
            imagepng($this->img); 
            imagedestroy($this->img); 
        } 
        public function showcode(){ 
            $this->createbg(); 
            $this->createcode(); 
            $this->createdisturb(); 
            $this->createfont(); 
            $this->output(); 
        } 
        //获取验证码 
        public function getcode(){ 
            return strtolower($this->code); 
        } 
    } 
?>

code.php

<?php 
    session_start(); 
    require_once 'verificationcode.class.php'; 
    $code=new verificationcode(); 
    $_session['code']=$code->getcode(); 
    $code->showcode(); 
?> 

验证码:<input type="text" name="code" /><img src="code.php" onclick="javascript:this.src='code.php?time='+math.random();" />