效果：
myvcode.class.php：封装创建验证码的类
1: <?php
2: /*
3: * file:myvcode.class.php
4: * 验证码类,类名Vcode
5: */
6: class Vcode
7: {
8: private $width; /*验证码宽度*/
9: private $height; /*验证码高度*/
10: private $codeNum; /*验证码字符个数*/
11: private $checkCode; /*验证码字符*/
12: private $image; /*验证码资源*/
13: private $pixNum; /*绘制干扰点的个数*/
14: private $lineNum; /*绘制干扰线的条数*/
15:
16: /*
17: *构造方法实例化验证码对象，并初始化数据
18: *@param int $width 设置默认宽度
19: *@param int $height 设置默认高度
20: *@param int $codeNum 设置验证码中的字符个数
21: *@param int $pixNum 设置干扰点的个数
22: *@param int $lineNum 设置干扰线的数量
23: */
24: function __construct($width=80,$height=40,$codeNum=4,$pixNum=40,$lineNum=5)
25: {
26: $this->width = $width;
27: $this->height = $height;
28: $this->codeNum = $codeNum;
29: $this->pixNum = $pixNum;
30: $this->lineNum = $lineNum;
31: }
32: /*内部私有方法,创建图像资源*/
33: private function getCreateImage()
34: {
35: $this->image = imagecreatetruecolor($this->width, $this->height);
36: $white = imagecolorallocate($this->image,0xff,0xff,0xff);
37: imagefill($this->image, 0, 0, $white);
38: $black = imagecolorallocate($this->image,0,0,0);
39: imagerectangle($this->image, 0, 0, $this->width-1, $this->height-1, $black);
40: }
41: /*内部私有方法,绘制字符，去掉o0Llz和012*/
42: private function createCheckCode()
43: {
44: $code = '3456789abcdefghijkmnpqrstuvwxyABCDEFGHIJKMNPQRSTUVWXY';
45: $this->checkCode = "";
46: for($i=0; $i<$this->codeNum;$i++)
47: {
48: $char = $code{rand(0,strlen($code) - 1)};
49: $this->checkCode .= $char;
50: $fontColor = imagecolorallocate($this->image, rand(0,128), rand(0,128),rand(0,128));
51: $fontSize = rand(3,5);
52: $x = rand(0,$this->width-imagefontwidth($fontSize));
53: $y = rand(0,$this->height-imagefontheight($fontSize));
54: imagechar($this->image, $fontSize, $x, $y, $char, $fontColor);
55: }
56: }
57: /*内部私有方法设置干扰元素*/
58: private function setDisturbColor()
59: {
60: /*绘制干扰点*/
61: for($i=0; $i<$this->pixNum; $i++)
62: {
63: $color = imagecolorallocate($this->image, rand(0,255), rand(0,255), rand(0,255));
64: imagesetpixel($this->image, rand(1,$this->width-2), rand(1,$this->height-2), $color);
65: }
66: /*绘制干扰线*/
67: for($i=0; $i<$this->lineNum; $i++)
68: {
69: $color = imagecolorallocate($this->image, rand(0,255), rand(0,255), rand(0,255));
70: imageline($this->image, rand(1,$this->width / 2), rand(1,$this->height / 2),
rand($this->width / 2,$this->width – 2), rand($this->height / 2,$this->height – 2), $color);
71: }
72: }
73: /*开启session保存 利用echo 输出图像*/
74: function __toString()
75: {
76: $_SESSION['code'] = strtoupper($this->checkCode);
77: $this->getCreateImage();
78: $this->createCheckCode();
79: $this->setDisturbColor();
80: $this->outputImg();
81: }
82: /*内部私有方法输出图像*/
83: private function outputImg()
84: {
85: header("content-type:image/png");
86: imagepng($this->image);
87: }
88: /*析构方法，释放对象*/
89: function __destruct()
90: {
91: imagedestroy($this->image);
92: }
93: }
94: ?>
imgcode.php输出图像
1: <?php
2: session_start();
3: require_once('myvcode.class.php');
4: echo new Vcode();
5: ?>
test.html:同过img标签引用
1: <img src="imgcode.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