如何利用PHP与FTP协议进行文件传输通信

<?php
$ftp_server = "ftp.example.com";
$ftp_username = "username";
$ftp_password = "password";

// 连接FTP服务器
$ftp_conn = ftp_connect($ftp_server);

// 登录FTP服务器
$login = ftp_login($ftp_conn, $ftp_username, $ftp_password);

// 判断连接和登录是否成功
if ($ftp_conn && $login) {
    echo "已成功连接并登录到FTP服务器";
} else {
    echo "连接或登录失败";
}

// 关闭FTP连接
ftp_close($ftp_conn);
?>

<?php
$local_file = "path/to/local_file.txt";
$remote_file = "path/to/remote_file.txt";

if (ftp_put($ftp_conn, $remote_file, $local_file, FTP_ASCII)) {
    echo "文件上传成功";
} else {
    echo "文件上传失败";
}
?>

<?php
$local_file = "path/to/local_file.txt";
$remote_file = "path/to/remote_file.txt";

if (ftp_get($ftp_conn, $local_file, $remote_file, FTP_ASCII)) {
    echo "文件下载成功";
} else {
    echo "文件下载失败";
}
?>

<?php
$directory = "path/to/ftp_directory/";

$file_list = ftp_nlist($ftp_conn, $directory);

foreach ($file_list as $file) {
    echo $file . "<br>";
}
?>

<?php
$remote_file = "path/to/remote_file.txt";

if (ftp_delete($ftp_conn, $remote_file)) {
    echo "文件删除成功";
} else {
    echo "文件删除失败";
}
?>