效果：

myvcode.class.PHP：封装创建验证码的类

PHP/** file:myvcode.class.PHP* 验证码类,类名Vcode*/class Vcode{private $width; /*验证码宽度*/private $height; /*验证码高度*/private $codeNum; /*验证码字符个数*/private $checkCode; /*验证码字符*/private $image; /*验证码资源*/private $pixNum; /*绘制干扰点的个数*/private $lineNum; /*绘制干扰线的条数*/

/**构造方法实例化验证码对象，并初始化数据 int $width 设置默认宽度 int $height 设置默认高度 int $codeNum 设置验证码中的字符个数 int $pixNum 设置干扰点的个数 int $lineNum 设置干扰线的数量*/function __construct($width=80,$height=40,$codeNum=4,$pixNum=40,$lineNum=5){$this->width = $width;$this->height = $height;$this->codeNum = $codeNum;$this->pixNum = $pixNum;$this->lineNum = $lineNum;}/*内部私有方法,创建图像资源*/private function getCreateImage(){$this->image = imagecreatetruecolor($this->width,$this->height);$white = imagecolorallocate($this->image,0xff,0xff);imagefill($this->image,$white);$black = imagecolorallocate($this->image,0);imagerectangle($this->image,$this->width-1,$this->height-1,$black);}/*内部私有方法,绘制字符，去掉o0Llz和012*/private function createCheckCode(){$code = '3456789abcdefghijkmnpqrstuvwxyABCDEFGHIJKMNPQRSTUVWXY';$this->checkCode = "";for($i=0; $i<$this->codeNum;$i++){$char = $code{rand(0,strlen($code) - 1)};$this->checkCode .= $char;$fontColor = imagecolorallocate($this->image,rand(0,128),128));$fontSize = rand(3,5);$x = rand(0,$this->width-imagefontwidth($fontSize));$y = rand(0,$this->height-imagefontheight($fontSize));imagechar($this->image,$fontSize,$x,$y,$char,$fontColor);}}/*内部私有方法设置干扰元素*/private function setDisturbColor(){/*绘制干扰点*/for($i=0; $i<$this->pixNum; $i++){$color = imagecolorallocate($this->image,255),255));imagesetpixel($this->image,rand(1,$this->width-2),$this->height-2),$color);}/*绘制干扰线*/for($i=0; $i<$this->lineNum; $i++){$color = imagecolorallocate($this->image,255));imageline($this->image,$this->width / 2),$this->height / 2),rand($this->width / 2,$this->width – 2),rand($this->height / 2,$this->height – 2),$color);

}}/*开启session保存 利用echo 输出图像*/function __toString(){$_SESSION['code'] = strtoupper($this->checkCode);$this->getCreateImage();$this->createCheckCode();$this->setDisturbColor();$this->outputImg();}/*内部私有方法输出图像*/private function outputImg(){header("content-type:image/png");imagepng($this->image);}/*析构方法，释放对象*/function __destruct(){imagedestroy($this->image);}}?>

imgcode.PHP输出图像

test.html:同过img标签引用

PHP;"> PHP">

可以加一个a标签，用js实现换一张效果：

/*局部刷新换验证码*/ function changeCode() { var imgcode = document.getElementById(‘code'); var change = document.getElementById(‘change'); change.onclick = function() { /*必须加后面的参数才能刷新*/ imgcode.src='code.PHP?tm'+Math.random(); } }

code和change分别是img和a的id