PHP Development Guide: How to Implement Website Access Control

PHP Development Guide: How to Implement Website Access Control

When developing a website, it is crucial to protect user data and ensure the security of sensitive information. A common and effective method is to restrict different users' access to different pages through website access control. This article will introduce how to use PHP to implement website access control and provide some code examples to help you get started quickly.

Step 1: Create a database table

First, we need to create a database table to store user information and permissions. The following is an example MySQL database table structure:

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) NOT NULL,
  `password` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `username` (`username`)
);

CREATE TABLE `permissions` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `page` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `user_id` (`user_id`)
);

In the above example, we created two tables: users and permissions. The users table is used to store the user's login information, and the permissions table is used to store the user's access permissions to different pages.

Step 2: Create a login function

Next, we need to create a login function so that users can verify their identity and obtain corresponding access rights. The following is a simple login page and backend processing code example:

<!-- login.html -->
<h2>用户登录</h2>
<form action="login.php" method="POST">
  <label for="username">用户名：</label>
  <input type="text" id="username" name="username" required><br>
  <label for="password">密码：</label>
  <input type="password" id="password" name="password" required><br>
  <input type="submit" value="登录">
</form>

// login.php
<?php
session_start();
$servername = "localhost";
$username = "root";
$password = "123456";
$dbname = "your_database_name";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 从登录表单获取用户名和密码
$username = $_POST['username'];
$password = $_POST['password'];

// 在用户表中验证用户信息
$sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = $conn->query($sql);

// 如果存在匹配的用户记录，则认为登录成功，把用户信息存入session
if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    $_SESSION['user_id'] = $row['id'];
    $_SESSION['username'] = $row['username'];
    header("Location: index.php"); // 重定向到首页
} else {
    echo "用户名或密码错误";
}

$conn->close();
?>

Step three: Check user access rights

Once the user successfully logs in and his information is stored in the session, we can Check the user's access rights on every page that requires access. The following is an example access control code:

// index.php
<?php
session_start();
// 检查用户是否登录
if (!isset($_SESSION['user_id'])) {
    header("Location: login.html"); // 重定向到登录页面
    exit();
}

// 创建数据库连接
$servername = "localhost";
$username = "root";
$password = "123456";
$dbname = "your_database_name";
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 获取当前页面的URL
$page = $_SERVER['PHP_SELF'];

// 检查当前用户是否具有访问当前页面的权限
$user_id = $_SESSION['user_id'];
$sql = "SELECT * FROM permissions WHERE user_id='$user_id' AND page='$page'";
$result = $conn->query($sql);

// 如果没有匹配的访问权限，则重定向到没有权限的页面
if ($result->num_rows == 0) {
    header("Location: no_permission.html");
    exit();
}

$conn->close();
?>

Using the above code, we can use include 'index.php'; on each page that requires access control to check user access permissions.

Summary

By using PHP to implement website access control, we can ensure that only users with corresponding permissions can access sensitive pages. In this article, we introduce how to create a database table to store user information and permissions, and provide corresponding code examples to implement login functionality and access control. I hope this article will be helpful to you in implementing website access control during development.

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