: Crucial for non-text files (images, zip files). It prevents corruption during transfer.
import org.apache.commons.net.ftp.FTP; import org.apache.commons.net.ftp.FTPClient; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; public class FtpDownloader { public static void main(String[] args) { String server = "://example.com"; int port = 21; String user = "username"; String password = "password"; String remoteFile = "/remote/path/file.txt"; String localFile = "C:/local/path/downloaded_file.txt"; FTPClient ftpClient = new FTPClient(); try { // 1. Connect and login ftpClient.connect(server, port); ftpClient.login(user, password); ftpClient.enterLocalPassiveMode(); // Important for firewalls ftpClient.setFileType(FTP.BINARY_FILE_TYPE); // Ensure binary transfer // 2. Download file try (OutputStream outputStream = new FileOutputStream(localFile)) { boolean success = ftpClient.retrieveFile(remoteFile, outputStream); if (success) { System.out.println("File downloaded successfully."); } else { System.out.println("Failed to download file."); } } // 3. Logout and disconnect ftpClient.logout(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (ftpClient.isConnected()) { ftpClient.disconnect(); } } catch (IOException ex) { ex.printStackTrace(); } } } } Use code with caution. Key Components of the Example:
Plain FTP sends credentials and data in plain text, which is insecure. For sensitive data, use . Instead of FTPClient , use FTPSClient :
: A convenient method that handles the input stream from the server and writes it to the provided OutputStream . 3. Securing FTP Downloads (FTPS)
This article provides a comprehensive guide to downloading FTP files using Java, featuring best practices, secure connections, and code examples. 1. Prerequisites and Setup