PHP验证码登录实例学习

<?php
/**
 * 验证码程序
 * edit www.jb200.com
*/
session_start();
function random($length, $numeric = 0) {
    mt_srand((double)microtime() * 1000000);
    if($numeric) {
        $hash = sprintf('%0'.$length.'d', mt_rand(0, pow(10, $length) - 1));
    } else {
        $hash = '';
        $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz';
        $max = strlen($chars) - 1;
        for($i = 0; $i < $length; $i++) {
            $hash .= $chars[mt_rand(0, $max)];
        }
    }
    return $hash;
}

$seccode = random(4, 1);

$_SESSION['seccode'] = $seccode;
$seccode = sprintf('%04d', $seccode);

if(!$nocacheheaders) {
    @header("Expires: -1");
    @header("Cache-Control: no-store, private, post-check=0, pre-check=0, max-age=0", FALSE);
    @header("Pragma: no-cache");
}

if(function_exists('imagecreate') && function_exists('imagecolorset') && function_exists('imagecopyresized') && function_exists('imagecolorallocate') && function_exists('imagesetpixel') && function_exists('imagechar') && function_exists('imagecreatefromgif') && function_exists('imagepng')) {

    $im = imagecreate(62, 25);
    $backgroundcolor = imagecolorallocate ($im, 255, 255, 255);

    $numorder = array(1, 2, 3, 4);
    shuffle($numorder);
    $numorder = array_flip($numorder);

    for($i = 1; $i <= 4; $i++) {
        $imcodefile = 'seccode/'.$seccode[$numorder[$i]].'.gif';
        $x = $numorder[$i] * 13 + mt_rand(0, 4) - 2;
        $y = mt_rand(0, 3);
        if(file_exists($imcodefile)) {
            $imcode = imagecreatefromgif($imcodefile);
            $data = getimagesize($imcodefile);
            imagecolorset($imcode, 0 ,mt_rand(50, 255), mt_rand(50, 128), mt_rand(50, 255));
            imagecopyresized($im, $imcode, $x, $y, 0, 0, $data[0] + mt_rand(0, 6) - 3, $data[1] + mt_rand(0, 6) - 3, $data[0], $data[1]);
        } else {
            $text_color = imagecolorallocate($im, mt_rand(50, 255), mt_rand(50, 128), mt_rand(50, 255));
            imagechar($im, 5, $x + 5, $y + 3, $seccode[$numorder[$i]], $text_color);
        }
    }

    $linenums = mt_rand(10, 32);
    for($i=0; $i <= $linenums; $i++) {
        $linecolor = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
        $linex = mt_rand(0, 62);
        $liney = mt_rand(0, 25);
        imageline($im, $linex, $liney, $linex + mt_rand(0, 4) - 2, $liney + mt_rand(0, 4) - 2, $linecolor);
    }

    for($i=0; $i <= 64; $i++) {
        $pointcolor = imagecolorallocate($im, mt_rand(50, 255), mt_rand(50, 255), mt_rand(50, 255));
        imagesetpixel($im, mt_rand(0, 62), mt_rand(0, 25), $pointcolor);
    }

    $bordercolor = imagecolorallocate($im , 150, 150, 150);
    imagerectangle($im, 0, 0, 61, 24, $bordercolor);

    header('Content-type: image/png');
    imagepng($im);
    imagedestroy($im);

} else {

    $numbers = array
        (
        0 => array('3c','66','66','66','66','66','66','66','66','3c'),
        1 => array('1c','0c','0c','0c','0c','0c','0c','0c','1c','0c'),
        2 => array('7e','60','60','30','18','0c','06','06','66','3c'),
        3 => array('3c','66','06','06','06','1c','06','06','66','3c'),
        4 => array('1e','0c','7e','4c','2c','2c','1c','1c','0c','0c'),
        5 => array('3c','66','06','06','06','7c','60','60','60','7e'),
        6 => array('3c','66','66','66','66','7c','60','60','30','1c'),
        7 => array('30','30','18','18','0c','0c','06','06','66','7e'),
        8 => array('3c','66','66','66','66','3c','66','66','66','3c'),
        9 => array('38','0c','06','06','3e','66','66','66','66','3c')
        );

    for($i = 0; $i < 10; $i++) {
        for($j = 0; $j < 6; $j++) {
            $a1 = substr('012', mt_rand(0, 2), 1).substr('012345', mt_rand(0, 5), 1);
            $a2 = substr('012345', mt_rand(0, 5), 1).substr('0123', mt_rand(0, 3), 1);
            mt_rand(0, 1) == 1 ? array_push($numbers[$i], $a1) : array_unshift($numbers[$i], $a1);
            mt_rand(0, 1) == 0 ? array_push($numbers[$i], $a1) : array_unshift($numbers[$i], $a2);
        }
    }

    $bitmap = array();
    for($i = 0; $i < 20; $i++) {
        for($j = 0; $j < 4; $j++) {
            $n = substr($seccode, $j, 1);
            $bytes = $numbers[$n][$i];
            $a = mt_rand(0, 14);
            switch($a) {
                case 1: str_replace('9', '8', $bytes); break;
                case 3: str_replace('c', 'e', $bytes); break;
                case 6: str_replace('3', 'b', $bytes); break;
                case 8: str_replace('8', '9', $bytes); break;
                case 0: str_replace('e', 'f', $bytes); break;
            }
            array_push($bitmap, $bytes);
        }
    }

    for($i = 0; $i < 8; $i++) {
        $a = substr('012', mt_rand(0, 2), 1) . substr('012345', mt_rand(0, 5), 1);
        array_unshift($bitmap, $a);
        array_push($bitmap, $a);
    }

    $image = pack('H*', '424d9e000000000000003e000000280000002000000018000000010001000000'.
            '0000600000000000000000000000000000000000000000000000FFFFFF00'.implode('', $bitmap));

    header('Content-Type: image/bmp');
    echo $image;
}
?>

<html>
<head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head>
<title>login登录界页-www.jb200.com</title>
<style type="text/css">
<!--
.textbox {
height: 18px;
width: 100px;
}
.text {
font-size: 14px;
vertical-align: bottom;
color: #0000FF;
}
.style1 {
font-size: 18px;
color: #0000FF;
font-family: "幼圆";
}
-->
</style>
</head>
<body>
<table width="200">
<tr><td align="center" valign="bottom" class="style1" bgcolor="#C7D3F9">请输入验证码</td>
</tr>
</table>
<form method="post" action="login.php">
<table width="200" border="0" bgcolor="C7D3F9">
  <tr>
    <td class="text">验证码：</td>
    <td align="right" valign="bottom"><input type="text" name="auth" class="textbox"></td>
  </tr>
</table>
<img src="ttt.php?act=yes" align="middle">
<table width="200"><tr><td align="right"><input type="button" value="看不清楚验证码" onclick="window.location.reload();"><input name="submit" type="submit" value="Submit"></td></tr></table>
</form>
</body>
</html>

<?php
session_start();
$auth = $_POST['auth'];
if($_SESSION['seccode'] == $auth)
{
  print '
  <script language=javascript>
   alert("登录成功！");
  </script>';
}else
{
  print '
  <script language=javascript>
   alert("登录失败，请重新登录！");
   self.window.location="login.html";
  </script>';
}
?>