Sometimes we need to create structure of a local directory on a remote FTP server, without uploading files to the server. That means creating a copy structure of the local directory on the server by creating only directories, not uploading files.

Based on the code presented in the article: How to upload a directory to a FTP server, by making some slightly modifications, we create a cut-down version of the utility class as follows:

import java.io.File;
import java.io.IOException;

import org.apache.commons.net.ftp.FTPClient;

/**
 * This utility class provides a method for uploading only structure of a
 * directory from local computer to a remote FTP server, based on Apache Commons
 * Net library.
 *
 * @author www.codejava.net
 *
 */
public class FTPUploadUtil {
	/**
	 * Upload structure of a directory (without uploading files) to a FTP
	 * server.
	 *
	 * @param ftpClient
	 *            an instance of org.apache.commons.net.ftp.FTPClient class.
	 * @param remoteDirPath
	 *            Path of the destination directory on the server.
	 * @param localParentDir
	 *            Path of the local directory being uploaded.
	 * @param remoteParentDir
	 *            Path of the parent directory of the current directory on the
	 *            server (used by recursive calls).
	 * @throws IOException
	 *             if any network or IO error occurred.
	 */
	public static void uploadDirStructure(FTPClient ftpClient,
			String remoteDirPath, String localParentDir, String remoteParentDir)
			throws IOException {

		File localDir = new File(localParentDir);
		File[] subFiles = localDir.listFiles();
		if (subFiles != null && subFiles.length > 0) {
			for (File item : subFiles) {
				if (item.isDirectory()) {
					String remoteFilePath = remoteDirPath + "/"
							+ remoteParentDir + "/" + item.getName();
					if (remoteParentDir.equals("")) {
						remoteFilePath = remoteDirPath + "/" + item.getName();
					}

					// create directory on the server
					boolean created = ftpClient.makeDirectory(remoteFilePath);
					if (created) {
						System.out.println("CREATED the directory: "
								+ remoteFilePath);
					} else {
						System.out.println("COULD NOT create the directory: "
								+ remoteFilePath);
					}

					// upload the sub directory
					String parent = remoteParentDir + "/" + item.getName();
					if (remoteParentDir.equals("")) {
						parent = item.getName();
					}

					localParentDir = item.getAbsolutePath();
					uploadDirStructure(ftpClient, remoteDirPath, localParentDir,
							parent);
				}
			}
		}
	}
}

Here is code of the test program:

import java.io.IOException;

import org.apache.commons.net.ftp.FTPClient;

public class UploadDirectoryStructureTest {

	public static void main(String[] args) {
		String server = "www.codejava.net";
		int port = 21;
		String user = "username";
		String pass = "password";

		FTPClient ftpClient = new FTPClient();

		try {
			// connect and login to the server
			ftpClient.connect(server, port);
			ftpClient.login(user, pass);

			// use local passive mode to pass firewall
			ftpClient.enterLocalPassiveMode();

			System.out.println("Connected");

			String remoteDirPath = "/Upload";
			String localDirPath = "D:/Test";

			FTPUploadUtil.uploadDirStructure(ftpClient, remoteDirPath,
					localDirPath, "");

			// log out and disconnect from the server
			ftpClient.logout();
			ftpClient.disconnect();

			System.out.println("Disconnected");
		} catch (IOException ex) {
			ex.printStackTrace();
		}
	}
}

Compile the utility class and the test program:

javac -cp commons-net-3.6.jar;. UploadDirectoryStructureTest.java

Run the test program:

java -cp commons-net-3.6.jar;. UploadDirectoryStructureTest

If the local directory D:/Test has the following structure:

Then the test program will output the following:

 

NOTES:Download the latest distribution of the Apache Commons Net library here.

 

Related Java FTP File Upload Tutorials:

• Upload files to FTP server using URLConnection class
• How to upload a directory to a FTP server
• Swing application to upload files to FTP server with progress bar

 

Other Java File Upload Tutorials:

• Java Servlet File Upload Example
• Spring MVC File Upload Tutorial
• Struts File Upload Example
• Java Upload files to database (Servlet + JSP + MySQL)

 

Other Java FTP Tutorials:

• Connect and login to a FTP server
• Java FTP create directory example
• Java FTP example - Change working directory
• Java FTP list files and directories example
• Java FTP file download tutorial and example
• Java FTP delete file example
• Java FTP example - Search for files and directories