php 登录实现
登录功能实现步骤
数据库准备
创建用户表存储用户名和密码（密码需加密存储）
CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(50) NOT NULL UNIQUE,
password VARCHAR(255) NOT NULL,
created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);前端表单设计
创建登录表单页面(login.html)
<form action="login.php" method="post">
<input type="text" name="username" placeholder="用户名" required>
<input type="password" name="password" placeholder="密码" required>
<button type="submit">登录</button>
</form>后端处理逻辑
创建登录处理脚本(login.php)
<?php
session_start();
$db = new PDO('mysql:host=localhost;dbname=your_db', 'username', 'password');
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
$username = $_POST['username'];
$password = $_POST['password'];
$stmt = $db->prepare("SELECT * FROM users WHERE username = ?");
$stmt->execute([$username]);
$user = $stmt->fetch();
if ($user && password_verify($password, $user['password'])) {
$_SESSION['user_id'] = $user['id'];
$_SESSION['username'] = $user['username'];
header('Location: dashboard.php');
exit;
} else {
$error = "用户名或密码错误";
}
}
?>密码加密处理
注册时应使用password_hash()加密
$hashedPassword = password_hash($plainPassword, PASSWORD_DEFAULT);会话管理
登录成功后跳转到受保护页面(dashboard.php)
<?php
session_start();
if (!isset($_SESSION['user_id'])) {
header('Location: login.php');
exit;
}
?>
<h1>欢迎, <?php echo htmlspecialchars($_SESSION['username']); ?></h1>安全增强措施
添加CSRF防护
if (empty($_POST['csrf_token']) || $_POST['csrf_token'] !== $_SESSION['csrf_token']) {
die('CSRF验证失败');
}添加登录尝试限制
if ($_SESSION['login_attempts'] > 3) {
die('尝试次数过多，请稍后再试');
}退出功能实现
创建退出脚本(logout.php)
<?php
session_start();
session_destroy();
header('Location: login.php');
?>
