1.验证码代码如下，新建一个含如下代码的php文件，此处取名为validatecode.php：
<?php
/*
* validatecode.php
*/
class validatecode {
private $charset = '0123456789';
private $code;
private $codelen = 4;
private $width = 163;
private $height = 30;
private $img;
private $font;
private $fontsize = 20;
private $fontcolor;
public function __construct($size) {
$this->font = dirname(__file__) . '/t1.ttf';
$this->codelen = $size;
$this->charset = str_repeat($this->charset, 4);
}
private function createcode() {
$_len = strlen($this->charset)-1;
for ($i=0;$i<$this->codelen;$i++) {
$this->code .= $this->charset[mt_rand(0,$_len)];
}
}
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);
}
private function createfont() {
$_x = ($this->width - 10) / $this->codelen;
for ($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[$i]);
}
}
private function createline() {
for ($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);
}
}
private function output() {
header('content-type:image/png');
imagepng($this->img);
imagedestroy($this->img);
}
public function doimg() {
$this->createbg();
$this->createcode();
$this->createline();
$this->createfont();
$this->output();
}
public function getcode() {
return strtolower($this->code);
}
}
?>
2.新建一个生成验证码的页面，此处取名为code.php，然后引入上面的php代码，实例化类，调用上面的doimg方法。
<?php
include("validatecode.php");
$obj = new validatecode(4);
$obj->doimg();
?>
3.上面的步骤做完后，就可以在其它页面通过img标签的src属性调用code.php。
<html>
<meta charset=utf8>
<head><title>验证码</title></head>
<body>
<form action="">
用户名：<input type="text" name="username"><br>
用户密码：<input type="password" name="userpwd"><br>
验证码：<input type="text" name="code"><img src="code.php" alt="yzm" onclick="this.src='code.php?id='+math.random()" width="90px">
</form>
</body>
</html>
这样就完成了。
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