php模拟登陆 验证码

<?php
session_start();

// 模拟登录处理
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $username = $_POST['username'];
    $password = $_POST['password'];
    $captcha = $_POST['captcha'];

    // 验证验证码
    if (strtolower($captcha) != strtolower($_SESSION['captcha'])) {
        die("验证码错误");
    }

    // 验证用户名和密码（这里假设用户名为admin，密码为password）
    if ($username == 'admin' && $password == 'password') {
        echo "登录成功";
    } else {
        echo "用户名或密码错误";
    }
}

// 生成验证码
$captcha = substr(md5(uniqid(mt_rand(), true)), 0, 5);
$_SESSION['captcha'] = $captcha;

$image = imagecreatetruecolor(100, 30);
$bgColor = imagecolorallocate($image, 255, 255, 255);
$textColor = imagecolorallocate($image, 0, 0, 0);

imagefilledrectangle($image, 0, 0, 100, 30, $bgColor);
imagestring($image, 5, 20, 5, $captcha, $textColor);

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