使用PHP生成验证码-面向对象方式

使用PHP生成验证码图像大致需要以下几个步骤：

1、创建图片并填充背景

2、生成随机验证码

3、生成干扰线和雪花

4、生成验证码文字

5、输出

<?php
//验证码类
class ValidateCode {
//随机因子
private $charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789';
private $code;//验证码
private $codelen = 4;//验证码长度
private $width = 130;//宽度
private $height = 50;//高度
private $img;//图像资源句柄
private $font;//字体
private $fontcolor;//字体颜色
private $fontsize = 20;//字体大小

public function __construct(){
$this->font = ROOT_PATH.'/font/elephant.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),$_x*$i+mt_rand(1,5),$this->height / 1.4,$this->fontcolor,$this->font,$this->code[$i]);
}
}

//生成线条和雪花
private function createLine(){
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);
}
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);
}

//对外生成
public function doimg(){
$this->createBg();
$this->createCode();
$this->createLine();
$this->createFont();
$this->outPut();
}

//获取验证码
public function getCode(){
return strtolower($this->code);
}
}

?>

然后再写一个PHP文件调用这个类的方法

<?php
require substr(dirname(__FILE__), 0, -7).'/init.inc.php';
$_vc = new ValidateCode();
$_vc->doimg();
$_SESSION['code'] = $_vc->getCode();
?>

最后在页面上直接调用就可以了

<img src="../config/code.php" onclick="javascript:this.src='../config/code.php?tm='+Math.random();" />