php 验证码

来源: 慕课网教程

产生一张图片

<?php
$image = imagecreatetruecolor(300,200);
$white = imagecolorallocate($image, 255,255,255);
$black = imagecolorallocate($image, 0, 0, 0);

imagefill($image, 0, 0, $white);
header(‘content-type: image/png‘);
imagepng($image);
imagedestroy($image);
?>

<?php
$filename = dirname(__FILE__).DIRECTORY_SEPARATOR.‘pic0.jpg‘;
$contents = file_get_contents($filename);
header(‘content-type: image/jpg‘);
echo $contents;
?>

添加数字

<?php
$image = imagecreatetruecolor(300,200);
$white = imagecolorallocate($image, 255,255,255);
$black = imagecolorallocate($image, 0, 0, 0);
imagefill($image, 0, 0, $white);

// 随机数字
for ($i = 0; $i < 4; $i++) {
    $fontsize = 6;
    $fontcontent = rand(0, 9);
    $fontcolor = imagecolorallocate($image, rand(0, 120), rand(0, 120), rand(0, 120));
    $x = $i * 100/4 + rand(5, 10);
    $y = rand(5, 10);
    imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);
}
header(‘content-type: image/png‘);
imagepng($image);
imagedestroy($image);
?>

干扰点和干扰线

for ($i = 0; $i < 150; $i++) {
    $pointcolor = imagecolorallocate($image, rand(50, 200), rand(50, 200), rand(50, 200));
    imagesetpixel($image, rand(1, 99), rand(1, 29), $pointcolor);
}

for ($i = 0; $i < 4; $i++) {
    $linecolor = imagecolorallocate($image, rand(150, 200), rand(150, 200), rand(150, 200));
    imageline($image, rand(1, 99), rand(1, 20), rand(1, 99), rand(1, 20), $linecolor);
}

实现字母和数字的验证码

$data = ‘3456789abcdefghjkmnpqrstuvwxy‘;   // 去掉 0 和 o, 1 和 l
$len = strlen($data);
for ($i = 0; $i < 4; $i++) {
    $fontsize = 8;
    $fontcontent = $data[rand(0, $len)];
    $fontcolor = imagecolorallocate($image, rand(0, 120), rand(0, 120), rand(0, 120));
    $x = $i * 100/4 + rand(5, 10);
    $y = rand(5, 10);
    imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);
}

验证登陆

verify.php

<?php
session_start();
$image = imagecreatetruecolor(100,30);
$white = imagecolorallocate($image, 255,255,255);
$black = imagecolorallocate($image, 0, 0, 0);
imagefill($image, 0, 0, $white);

$captch_code = ‘‘;

$data = ‘3456789abcdefghjkmnpqrstuvwxy‘;
$len = strlen($data);
for ($i = 0; $i < 4; $i++) {
    $fontsize = 8;
    $fontcontent = $data[rand(0, $len)];
    $captch_code .= $fontcontent;
    $fontcolor = imagecolorallocate($image, rand(0, 120), rand(0, 120), rand(0, 120));
    $x = $i * 100/4 + rand(5, 10);
    $y = rand(5, 10);
    imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);
}

$_SESSION[‘authcode‘] = $captch_code;

for ($i = 0; $i < 150; $i++) {
    $pointcolor = imagecolorallocate($image, rand(50, 200), rand(50, 200), rand(50, 200));
    imagesetpixel($image, rand(1, 99), rand(1, 29), $pointcolor);
}

for ($i = 0; $i < 4; $i++) {
    $linecolor = imagecolorallocate($image, rand(150, 200), rand(150, 200), rand(150, 200));
    imageline($image, rand(1, 99), rand(1, 20), rand(1, 99), rand(1, 20), $linecolor);
}

header(‘content-type: image/png‘);
imagepng($image);
imagedestroy($image);
?>

form.php

<?php
if (isset($_REQUEST[‘authcode‘])) {
    session_start();

    if (strtolower($_REQUEST[‘authcode‘]) == $_SESSION[‘authcode‘]) {
        echo ‘<font color="#00C"> succees </font>‘;
    } else {
        echo ‘<font color="#C00"> fail </font>‘;
    }
    exit();
}
?>

<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8" />
    <title>test</title>
  </head>
  <body>
    <form method="post" action="<?php echo $_SERVER[PHP_SELF]; ?>">
      <p>验证码图片: <img border="1" src="./verify.php?r=<?php echo rand(); ?>" width="120px"></p>
      <p><input type="text" size="10" name="authcode" value=""></p>
      <p><input type="submit" value="submit"> </p>
    </form>
  </body>
</html>

实现刷新

<?php
if (isset($_REQUEST[‘authcode‘])) {
    session_start();

    if ($_REQUEST[‘authcode‘] == $_SESSION[‘authcode‘]) {
        echo ‘<font color="#00C"> succees </font>‘;
    } else {
        echo ‘<font color="#C00"> fail </font>‘;
    }
    exit();
}
?>

<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8" />
    <title>test</title>
  </head>
  <body>
    <form method="post" action="<?php echo $_SERVER[PHP_SELF]; ?>">
      <p>
        验证码图片: <img id="captcha_img" border="1" src="./verify.php?r=<?php echo rand(); ?>" width="120px">
        <a href="javascript:void(0)" onclick="document.getElementById(‘captcha_img‘).src=‘./verify.php?r=‘+Math.random()">换一个?</a>
      </p>
      <p><input type="text" size="10" name="authcode" value=""></p>
      <p><input type="submit" value="submit"> </p>
    </form>
  </body>
</html>

图片验证码

form_img.php

<?php
session_start();

$table = array(
    ‘pic0‘ => ‘dog‘,
    ‘pic1‘ => ‘cat‘,
    ‘pic2‘ => ‘fish‘,
    ‘pic3‘ => ‘bird‘,
);

$index = rand(0, 3);

$value = $table[‘pic‘.$index];
$_SESSION[‘authcode‘] = $value;

$filename = dirname(__FILE__).DIRECTORY_SEPARATOR.‘pic‘.$index.‘.jpg‘;
$contents = file_get_contents($filename);
header(‘content-type: image/jpg‘);
echo $contents;
?>


<?php
if (isset($_REQUEST[‘authcode‘])) {
    session_start();
    if ($_REQUEST[‘authcode‘] == $_SESSION[‘authcode‘]) {
        echo ‘<font color= "#f00";>succeed</font>‘;
    } else {
        echo ‘<font color= "#00f";>fail</font>‘;
    }
    exit();
}
?>

<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8" />
    <title>test</title>
  </head>
  <body>
    <form methos="post" action="<?php echo $_SERVER[PHP_SELF]; ?>">
      <p>图片: <img id="captcha_img" src="./verify_img.php?r=<?php echo rand(); ?>" width="200" height="100">
        <a href="javascript:void(0)" onclick="document.getElementById(‘captcha_img‘).src=‘./verify_img.php?r=‘+Math.random()">换一个</a>
      </p>
      <p><input type="text" name="authcode" size="10"></p>
      <input type="submit" value="submit">
    </form>
  </body>
</html>

verify_img.php

<?php
session_start();

$table = array(
    ‘pic0‘ => ‘dog‘,
    ‘pic1‘ => ‘cat‘,
    ‘pic2‘ => ‘fish‘,
    ‘pic3‘ => ‘bird‘,
);

$index = rand(0, 3);

$value = $table[‘pic‘.$index];
$_SESSION[‘authcode‘] = $value;
$filename = dirname(__FILE__).DIRECTORY_SEPARATOR.‘pic‘.$index.‘.jpg‘;
$contents = file_get_contents($filename);
header(‘content-type: image/jpg‘);
echo $contents;
?>