php如何实现登录验证
实现PHP登录验证的方法
数据库准备
创建用户表存储用户名和密码（建议使用哈希加密存储）
CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(50) NOT NULL UNIQUE,
password VARCHAR(255) NOT NULL
);登录表单设计
HTML表单提交用户名和密码
<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>密码验证逻辑
使用password_hash()创建和password_verify()验证密码
// 注册时哈希密码
$hashedPassword = password_hash($plainPassword, PASSWORD_DEFAULT);
// 登录时验证
if (password_verify($inputPassword, $storedHash)) {
// 验证成功
}会话管理
成功登录后创建会话
session_start();
$_SESSION['user_id'] = $user['id'];
$_SESSION['username'] = $user['username'];安全防护措施
防止SQL注入使用预处理语句
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
$stmt->execute([$username]);
$user = $stmt->fetch();完整登录处理示例
session_start();
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
$username = trim($_POST['username']);
$password = $_POST['password'];
$pdo = new PDO('mysql:host=localhost;dbname=test', 'user', 'pass');
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
$stmt->execute([$username]);
$user = $stmt->fetch();
if ($user && password_verify($password, $user['password'])) {
$_SESSION['user_id'] = $user['id'];
header('Location: dashboard.php');
exit;
} else {
$error = "用户名或密码错误";
}
}登录状态检查
session_start();
if (!isset($_SESSION['user_id'])) {
header('Location: login.php');
exit;
}退出登录实现
session_start();
session_destroy();
header('Location: login.php');
exit;
