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
复制代码 代码如下:
<?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

复制代码 代码如下:
<?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();" />