本文目录一览：
求一个php验证码及如何使用的例子?
以前项目中的东西
在没有GB库的情况下也可以生成验证码
关键部分做出了注释
img src="image.php"
?php
//存为文件 image.php
error_reporting(E_ALL ^ E_NOTICE);
require_once('image.class.php');
$image_model = new Image();
//可以在此处更改属性达到验证码不同大小的图片
$image_model-outputBrowser();
?
?php
/*
* \验证码生成类 存为文件image.class.php
* \如果不支持GD库，则采用像素画法
* \详见
*/
class Image
{
var $img_height = 20; //图片的长
var $img_width = 68; //图片的宽
var $img_cache = ''; //图像信息缓存
var $check_number = ''; //验证码
var $lenght = 4; //验证码位数
var $is_gd = false;
//'----------以下为不支持GD需要的变量
var $pixels = '';
var $digits = '';
var $lines = '';
var $data = '';
var $chunk = '';
var $crc_table = '';
function Image()
{
session_start();
session_register("check_number");
$this-session = $_SESSION;
$this-is_gd = function_exists('gd_info') ? true : false;
$this-getCheckNumber();
if( $this-is_gd ):
$this-getFromGD();
else:
$this-getFromCode();
endif;
}
//'----浏览器输出
function outputBrowser()
{
if( $this-is_gd )
{
Header("Content-type: image/png"); //告诉浏览器，下面的数据是图片，而不要按文字显示
Imagepng($this-img_cache); //生成png格式。。。嘿嘿效果蛮像回事的嘛。。。
ImageDestroy($this-img_cache);
}
else echo($this-img_cache);
}
//'----文件输出
function outputFile($filename=null)
{
if(!$filename)$filename=time().'.png';
$fp = fopen($filename, 'w+');
fwrite($fp, $this-img_cache);
fclose($fp);
}
//'----得到验证码
function getCheckNumber()
{
//srand(microtime() * 100000);//PHP420后，srand不是必须的
for($Tmpa=0;$Tmpa$this-lenght;$Tmpa++)
{
$this-check_number.= $this-is_gd ? dechex(rand(0,15)) : rand(0,3);
}
unset($Tmpa);
$this-session['check_number'] = strtoupper($this-check_number);
}
//'----用GD库生成
function getFromGD()
{
//$black = '';
$this-img_cache = imageCreate($this-img_width,$this-img_height); //生成图片
//图片底色，ImageColorAllocate第1次定义颜色PHP就认为是底色了
$black = ImageColorAllocate($this-img_cache, 255,255,255);
//下面该生成雪花背景了，其实就是在图片上生成一些符号
//先用100个做测试
/*
for ($i=1; $i=15; $i++)
{
imageString($this-img_cache,1,mt_rand(1,$this-img_height-10),mt_rand(1,$this-img_width-10),".",
imageColorAllocate($this-img_cache,mt_rand(100,255),mt_rand(0,250),mt_rand(0,200)));
//哈，看到了吧，其实也不是雪花，就是生成＊号而已。为了使它们看起来"杂乱无章、5颜6色"，就得在1个1个生成它们的时候，让它们的位置、颜色，甚至大小都用随机数，rand()或mt_rand都可以完成。
}
*/
//上面生成了背景，现在就该把已经生成的随机数放上来了。道理和上面差不多，随机数1个1个地放，同时让他们的位置、大小、颜色都用成随机数~~
//为了区别于背景，这里的颜色不超过200，上面的不小于200
imagettftext($this-img_cache, 20, 0, 10, 20, $black, "./html/VINERITC.TTF", "AC67");
for ($i=0;$istrlen($this-session['check_number']);$i++)
{
imagettftext($this-img_cache, 14, rand(0,30), $i*$this-img_width/4 + 3, 17, imageColorAllocate($this-img_cache,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200)), "./html/VINERITC.TTF", $this-session['check_number'][$i]);
}
for($i=0;$i100;$i++)//加入干扰象素
{
imagesetpixel($this-img_cache, rand()%70 , rand()%30 , imageColorAllocate($this-img_cache,mt_rand(100,255),mt_rand(0,250),mt_rand(0,200)));
}
$black = ImageColorAllocate($this-img_cache, 0,0,0); //定义需要的黑色
//先成一黑色的矩形把图片包围
ImageRectangle($this-img_cache,0,0, $this-img_width-1,$this-img_height-1, $black);
}
//End Function getGD
#-----------------------------------------------------------------------------------------------------------------------
function set_4pixel($r, $g, $b, $x, $y)
{
$ofs = 3 * ($this-img_width * $y + $x);
$this-pixels[$ofs] = chr($r);
$this-pixels[$ofs + 1] = chr($g);
$this-pixels[$ofs + 2] = chr($b);
$this-pixels[$ofs + 3] = chr($r);
$this-pixels[$ofs + 4] = chr($g);
$this-pixels[$ofs + 5] = chr($b);
$ofs += 3 * $this-img_width;
$this-pixels[$ofs] = chr($r);
$this-pixels[$ofs + 1] = chr($g);
$this-pixels[$ofs + 2] = chr($b);
$this-pixels[$ofs + 3] = chr($r);
$this-pixels[$ofs + 4] = chr($g);
$this-pixels[$ofs + 5] = chr($b);
}
//生成数字图象的函数
function draw2digits($x, $y, $number)
{
//$this-draw_digit($x, $y, intval($number / 10) );
$this-draw_digit($x + 11, $y, $number % 10);
}
function draw_digit($x, $y, $digit)
{
$digit = $this-digits[$digit];
$m = 8;
for($b = 1, $i = 0; $i 7; $i++, $b *= 2)
{
if(($b $digit) == $b)
{
$j = $i * 4;
$x0 = $this-lines[$j] * $m + $x;
$y0 = $this-lines[$j + 1] * $m + $y;
$x1 = $this-lines[$j + 2] * $m + $x;
$y1 = $this-lines[$j + 3] * $m + $y;
if($x0 == $x1)
{
$ofs = 3 * ($this-img_width * $y0 + $x0);
for($h = $y0; $h = $y1; $h++, $ofs += 3 * $this-img_width)
{
$this-pixels[$ofs] = chr(0);
$this-pixels[$ofs + 1] = chr(0);
$this-pixels[$ofs + 2] = chr(0);
}
}
else
{
$ofs = 3 * ($this-img_width * $y0 + $x0);
for($w = $x0; $w = $x1; $w++)
{
$this-pixels[$ofs++] = chr(0);
$this-pixels[$ofs++] = chr(0);
$this-pixels[$ofs++] = chr(0);
}
}
}//End if
}//End for
}
//将文字加入到图象中
function add_chunk($type)
{
// chunk :为层
// length: 4 字节: 用来计算 chunk
// chunk type: 4 字节
// chunk data: length bytes
// CRC: 4 字节: 循环冗余码校验
// copy data and create CRC checksum
$len = strlen($this-data);
$this-chunk = pack("c*", ($len 24) 255,
($len 16) 255,
($len 8) 255,
$len 255);
$this-chunk .= $type;
$this-chunk .= $this-data;
//calculate a CRC checksum with the bytes chunk[4..len-1]
$z = 16777215;
$z |= 255 24;
$c = $z;
for ($n = 4; $n strlen($this-chunk); $n++) {
$c8 = ($c 8) 0xffffff;
$c = $this-crc_table[($c ^ ord($this-chunk[$n])) 0xff] ^ $c8;
}
$crc = $c ^ $z;
$this-chunk .= chr(($crc 24) 255);
$this-chunk .= chr(($crc 16) 255);
$this-chunk .= chr(($crc 8) 255);
$this-chunk .= chr($crc 255);
//将结果加到$img_cache中
$this-img_cache .= $this-chunk;
}
//主程序
function getFromCode()
{
//填充
for($h = 0; $h $this-img_height; $h++)
{
for($w = 0; $w $this-img_width; $w++)
{
$r = 100 / $this-img_width * $w + 155;
$g = 100 / $this-img_height * $h + 155;
$b = 255 - (100 / ($this-img_width + $this-img_height) * ($w + $h));
$this-pixels .= chr($r);
$this-pixels .= chr($g);
$this-pixels .= chr($b);
}
}
$this-digits = array(95, 5, 118, 117, 45, 121, 123, 69, 127, 125);
$this-lines = array(1, 1, 1, 2, 0, 1, 0, 2, 1, 0, 1, 1, 0, 0, 0, 1, 0, 2, 1, 2, 0, 1, 1, 1, 0, 0, 1, 0);
for($i=0; $i$this-lenght; $i++)
{
$this-draw2digits($i*13, 2, $this-check_number[$i]);
}
//$this-set_4pixel(0, 0, 0, 26, 7);
//$this-set_4pixel(0, 0, 0, 26, 13);
//$this-set_4pixel(0, 0, 0, 52, 7);
//$this-set_4pixel(0, 0, 0, 52, 13);
//创建循环冗余码校验表
$z = -306674912;// = 0xedb88320
for ($n = 0; $n 256; $n++)
{
$c = $n;
for ($k = 0; $k 8; $k++)
{
$c2 = ($c 1) 0x7fffffff;
if($c 1) $c = $z ^ ($c2);
else $c = $c2;
}
$this-crc_table[$n] = $c;
}
// PNG file signature
$this-img_cache = pack("c*", 137,80,78,71,13,10,26,10);
// IHDR chunk data:
// width: 4 bytes
// height: 4 bytes
// bit depth: 1 byte (8 bits per RGB value)
// color type: 1 byte (2 = RGB)
// compression method: 1 byte (0 = deflate/inflate)
// filter method: 1 byte (0 = adaptive filtering)
// interlace method: 1 byte (0 = no interlace)
$this-data = pack("c*", ($this-img_width24) 255,
($this-img_width 16) 255,
($this-img_width 8) 255,
$this-img_width 255,
($this-img_height 24) 255,
($this-img_height 16) 255,
($this-img_height 8) 255,
$this-img_height 255, 8, 2, 0, 0, 0);
$this-add_chunk("IHDR");
//以下不敢乱翻译，请自行参考
// scanline:
// filter byte: 0 = none
// RGB bytes for the line
// the scanline is compressed with "zlib", method 8 (RFC-1950):
// compression method/flags code: 1 byte ($78 = method 8, 32k window)
// additional flags/check bits: 1 byte ($01: FCHECK = 1, FDICT = 0, FLEVEL = 0)
// compressed data blocks: n bytes
// one block (RFC-1951):
// bit 0: BFINAL: 1 for the last block
// bit 1 and 2: BTYPE: 0 for no compression
// next 2 bytes: LEN (LSB first)
// next 2 bytes: one's complement of LEN
// LEN bytes uncompressed data
// check value: 4 bytes (Adler-32 checksum of the uncompressed data)
$len = ($this-img_width * 3 + 1) * $this-img_height;
$this-data = pack("c*", 0x78, 0x01, 1, $len 255, ($len8) 255, 255 - ($len 255), 255 - (($len 8) 255) );
$start = strlen($this-data);
$i2 = 0;
for($h = 0; $h $this-img_height; $h++)
{
$this-data .= chr(0);
for($w = 0; $w $this-img_width * 3; $w++)
{
$this-data .= $this-pixels[$i2++];
}
}
//calculate a Adler32 checksum with the bytes data[start..len-1]
$s1 = 1;
$s2 = 0;
for ($n = $start; $n strlen($this-data); $n++)
{
$s1 = ($s1 + ord($this-data[$n])) % 65521;
$s2 = ($s2 + $s1) % 65521;
}
$adler = ($s2 16) | $s1;
$this-data .= chr(($adler 24) 255);
$this-data .= chr(($adler 16) 255);
$this-data .= chr(($adler 8) 255);
$this-data .= chr($adler 255);
$this-add_chunk("IDAT");
//IEND: marks the end of the PNG-file
$this-data = "";
$this-add_chunk("IEND");
//列印图象
//echo($this-img_cache);
}
}//End Class
?
怎么用PHP写个验证码
首先，当用户打开页面时随机产生一个session，然后根据这个值生成验证码图片。
第二，将验证码图片显示到表单上。
第三，当用户提交时表单时，比较session里的值与表单中验证码的值进行比较。
简单的实现过程：
复杂的验证码图片生成：
php验证码怎么实现
1. 新建code.php验证码生成文件
在此之前必须打开php的GD库，修改php.ini文件的配置，取消extension=php_gd2.dll前面的分号。代码如下：
?php
session_start();
//生成验证码图片
Header("Content-type: image/PNG");
$im = imagecreate(44,18);
$back = ImageColorAllocate($im, 245,245,245);
imagefill($im,0,0,$back); //背景
srand((double)microtime()*1000000);
//生成4位数字
for($i=0;$i4;$i++){
$font = ImageColorAllocate($im, rand(100,255),rand(0,100),rand(100,255));
$authnum=rand(1,9);
$vcodes.=$authnum;
imagestring($im, 5, 2+$i*10, 1, $authnum, $font);
}
for($i=0;$i100;$i++) //加入干扰象素
{
$randcolor = ImageColorallocate($im,rand(0,255),rand(0,255),rand(0,255));
imagesetpixel($im, rand()p , rand()0 , $randcolor);
}
ImagePNG($im);
ImageDestroy($im);
$_SESSION['Checknum'] = $vcodes;
?
2. 显示验证码图片
在需要显示验证码的页面中加入
input type="text" name="passcode"
img src="code.php"
3.判断并获取验证码的值
验证码是通过第一步骤代码中的$_SESSION['Checknum'] = $vcodes;赋的值，所以验证码的值存在$_SESSION['Checknum']当中。在验证页面，使用以下代码，
...
session_start();//启动会话
$code=$_POST["passcode"];
if( $code == $_SESSION["Checknum"])
{...}即可完成验证码登录。
运行截图：
望采纳，谢谢
