PHP生成验证码类，下面就是类代码

<?php
/************************************************************************
//FILE:ImageCode
//DONE:生成动态验证码类
************************************************************************/
class ImageCode{
private width; //验证码图片宽度
private height; //验证码图片高度
private codeNum; //验证码字符个数
private checkCode; //验证码字符
private image; //验证码画布
/************************************************************************
// Function:构造函数
// Done:成员属性初始化
************************************************************************/
function __construct(width=60,height=20,codeNum=4)
{
this->width = width;
this->height = height;
this->codeNum = codeNum;
this->checkCode = this->createCheckCode();
}
function showImage()
{
this->getcreateImage();
this->outputText();
this->setDisturbColor();
this->outputImage();
}
function getCheckCode()
{
return this->chekCode;
}
private function getCreateImage()
{
this->image = imagecreatetruecolor(this->width,this->height);
back = imagecolorallocate(this->image,255,255,255);
border = imagecolorallocate(this->image,255,255,255);
imagefilledrectangle(this->image,0,0,this->width-1,this->height-1,border);
//使用纯白色填充矩形框，这里用的话后面干扰码失效
/*如果想用干扰码的话使用下面的*/
//imagerectangle(this->image,0,0,this->width-1,this->height-1,border);
}
private function createCheckCode()
{
for(i=0;i<this->codeNum;i++)
{
number = rand(0,2);
switch(number)
{
case 0: rand_number = rand(48,57); break;//数字
case 1: rand_number = rand(65,90);break;//大写字母
case 2: rand_number = rand(97,122);break;//小写字母
}
asc = sprintf("%c",rand_number);
asc_number = asc_number.asc;
}
return asc_number;
}
private function setDisturbColor()//干扰吗设置
{
for(i=0;i<=100;i++)
{
//color = imagecolorallocate(this->image,rand(0,255),rand(0,255),rand(0,255));
color = imagecolorallocate(this->image,255,255,255);
imagesetpixel(this->image,rand(1,this->width-2),rand(1,this->height-2),color);
}
//color = imagecolorallocate(this->image,0,0,0);
//imagesetpixel(this->image,rand(1,this->width-2),rand(1,this->height-2),color);


}
private function outputText()
{
//随机颜色、随机摆放、随机字符串向图像输出
for(i=0;i<=this->codeNum;i++)
{
bg_color = imagecolorallocate(this->image,rand(0,255),rand(0,128),rand(0,255));
x = floor(this->width/this->codeNum)*i+3;
y = rand(0,this->height-15);
imagechar(this->image,5,x,y,this->checkCode[i],bg_color);
}
}

private function outputImage()
{
if(imagetypes()&IMG_GIF)
{
header("Content_type:image/gif");
imagegif(this->image);
}
elseif(imagetypes()&IMG_JPG)
{

header("Content-type:image/jpeg");
imagejpeg(this->image,"",0.5);
}
elseif(imagetypes()&IMG_PNG)
{
header("Content-type:image/png");
imagejpeg(this->image);
}
elseif(imagetypes()&IMG_WBMP)
{
header("Content-type:image/vnd.wap.wbmp");
imagejpeg(this->image);
}
else
{
die("PHP不支持图像创建");
}
}

function __destruct()
{
imagedestroy(this->image);
}
}

/*显示*/
/*******************************************************************
session_start();
image = new ImageCode(60,20,4);
image->showImage();
_SESSION['ImageCode'] = image->getCheckCode();
*******************************************************************/

?>