PHP and FTP: Create a multi-user file sharing system

PHP and FTP: Create a file sharing system suitable for multiple users

With the development and popularity of the Internet, more and more people begin to need to share files between different devices. To meet this need, it is important to create a file sharing system that works for multiple users. In this article, we will build such a system using PHP and FTP and provide some sample code.

First, let us understand FTP. FTP (File Transfer Protocol) is a protocol used for file transfer on the network. It allows users to connect to an FTP server through an FTP client and upload or download files. In our file sharing system, FTP will play an important role in handling the operations of users uploading and downloading files.

In order to implement a multi-user file sharing system, we first need to create a membership system to enable users to register, log in and manage their files. The following is a simple PHP code example for user registration function:

<?php
// 连接到数据库
$conn = mysqli_connect('localhost', 'username', 'password', 'database_name');

// 注册函数
function register($username, $password) {
   global $conn;
   
   // 检查用户名是否已经存在
   $query = "SELECT * FROM users WHERE username='$username'";
   $result = mysqli_query($conn, $query);
   if (mysqli_num_rows($result) > 0) {
      return false;
   }
   
   // 创建新用户
   $query = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
   mysqli_query($conn, $query);
   
   return true;
}

// 注册表单提交后的处理
if (isset($_POST['register'])) {
   $username = $_POST['username'];
   $password = $_POST['password'];
   
   if (register($username, $password)) {
      echo "注册成功！";
   } else {
      echo "用户名已存在！";
   }
}
?>

The register function in the above code is used to insert the user's registration information into the database. After the registration form is submitted, we get the username and password in the form and call the register function to register the new user.

Let’s look at a sample code for user login:

<?php
// 用户登录函数
function login($username, $password) {
   global $conn;
   
   // 检查用户名和密码是否正确
   $query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
   $result = mysqli_query($conn, $query);
   if (mysqli_num_rows($result) == 1) {
      return true;
   }
   
   return false;
}

// 登录表单提交后的处理
if (isset($_POST['login'])) {
   $username = $_POST['username'];
   $password = $_POST['password'];
   
   if (login($username, $password)) {
      echo "登录成功！";
   } else {
      echo "用户名或密码错误！";
   }
}
?>

In the above code, the login function is used to verify whether the user name and password entered by the user are correct. If the verification is successful, the user will be redirected to the main interface of the file sharing system.

Once the user successfully logs in, they will be able to upload and download files. In order to achieve this function, we need to use an FTP client to communicate with the FTP server. The following is a sample code using PHP FTP functions for uploading files:

<?php
// 上传文件函数
function uploadFile($localPath, $remotePath) {
   // 建立FTP连接
   $ftp = ftp_connect('ftp.example.com');
   ftp_login($ftp, 'username', 'password');
   
   // 上传文件
   ftp_put($ftp, $remotePath, $localPath, FTP_BINARY);
   
   // 关闭FTP连接
   ftp_close($ftp);
}

// 处理上传请求
if (isset($_FILES['file'])) {
   $file = $_FILES['file'];
   $localPath = $file['tmp_name'];
   $remotePath = '/path/to/ftp/folder/' . $file['name'];
   
   uploadFile($localPath, $remotePath);
   echo "文件上传成功！";
}
?>

In the above code, we have used the ftp_connect function to connect to the FTP server and the ftp_login function for authentication. We then use the ftp_put function to actually upload the file.

In addition to uploading files, we also need to implement the function of downloading files. The following is a sample code for downloading files from an FTP server:

<?php
// 下载文件函数
function downloadFile($remotePath, $localPath) {
   // 建立FTP连接
   $ftp = ftp_connect('ftp.example.com');
   ftp_login($ftp, 'username', 'password');
   
   // 下载文件
   ftp_get($ftp, $localPath, $remotePath, FTP_BINARY);
   
   // 关闭FTP连接
   ftp_close($ftp);
}

// 处理下载请求
if (isset($_GET['file'])) {
   $remotePath = '/path/to/ftp/folder/' . $_GET['file'];
   $localPath = '/path/to/local/folder/' . $_GET['file'];
   
   downloadFile($remotePath, $localPath);
   echo "文件下载成功！";
}
?>

In the above code, we use the ftp_get function to download files from the FTP server and specify a local path to save the downloaded file.

With the above sample code, we can create a basic multi-user file sharing system. Users can register, log in and upload and download their files. Using FTP as the file transfer protocol ensures the safe transfer of files. Of course, this is just a simple example, and you can extend it to more complex functions based on actual needs.

Summary:
This article introduces how to use PHP and FTP to create a file sharing system suitable for multiple users. We demonstrate some key code examples, including user registration, user login, file upload, and file download functionality. This code can help you build a basic file sharing system and expand further from there. Hope this article helps you!

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