In this article, we are going to develop an example of how to remove a non-empty directory (which includes sub directories and files) on a remote FTP server, using API of the Apache Commons Net library.

To delete all content of a non-empty directory, it’s important to list all content of the directory, its sub directories, sub directories of sub directories, and so on (listing recursively). The solution is a combination of the techniques which are described in the following articles:

• • List files and directories recursively.
  • Remove an empty directory.
  • Delete a file.

For the purpose of reusability, we implement a static method in a utility class as follows:

import java.io.IOException;

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

/**
 * This utility class implements a method that removes a non-empty directory
 * on a FTP server.
 * @author www.codejava.net
 */
public class FTPUtil {

	/**
	 * Removes a non-empty directory by delete all its sub files and
	 * sub directories recursively. And finally remove the directory.
	 */
	public static void removeDirectory(FTPClient ftpClient, String parentDir,
			String currentDir) throws IOException {
		String dirToList = parentDir;
		if (!currentDir.equals("")) {
			dirToList += "/" + currentDir;
		}

		FTPFile[] subFiles = ftpClient.listFiles(dirToList);

		if (subFiles != null && subFiles.length > 0) {
			for (FTPFile aFile : subFiles) {
				String currentFileName = aFile.getName();
				if (currentFileName.equals(".") || currentFileName.equals("..")) {
					// skip parent directory and the directory itself
					continue;
				}
				String filePath = parentDir + "/" + currentDir + "/"
						+ currentFileName;
				if (currentDir.equals("")) {
					filePath = parentDir + "/" + currentFileName;
				}

				if (aFile.isDirectory()) {
					// remove the sub directory
					removeDirectory(ftpClient, dirToList, currentFileName);
				} else {
					// delete the file
					boolean deleted = ftpClient.deleteFile(filePath);
					if (deleted) {
						System.out.println("DELETED the file: " + filePath);
					} else {
						System.out.println("CANNOT delete the file: "
								+ filePath);
					}
				}
			}

			// finally, remove the directory itself
			boolean removed = ftpClient.removeDirectory(dirToList);
			if (removed) {
				System.out.println("REMOVED the directory: " + dirToList);
			} else {
				System.out.println("CANNOT remove the directory: " + dirToList);
			}
		}
	}
}

Notice that the method removeDirectory() is using recursive algorithm, which invokes itself if the file being listed is also a directory. That allows the method to work with directory structure in any depth level (only limited to the memory).

Here is a test program that connects to a FTP server, remove the directory “/Test” and disconnects from the server:

import java.io.IOException;

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

/**
 * This program demonstrates how to remove a non-empty directory on a FTP
 * server, using Apache Commons Net FTP library.
 *
 * @author www.codejava.net
 *
 */
public class FTPRemoveNonEmptyDir {

	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 dirPath = "/Test";

			FTPUtil.removeDirectory(ftpClient, dirPath, "");

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

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

 

NOTES:Remember to change the server address, username and password according to your own FTP account.

Compile the utility class:

javac -cp commons-net-VERSION.jar FTPUtil.java

Compile the test program:

javac -cp commons-net-VERSION.jar;. FTPRemoveNonEmptyDir.java

Run the test program:

java -cp commons-net-VERSION.jar;. FTPRemoveNonEmptyDir

Where commons-net-VERSION.jar is runtime library of the Apache Commons Net. You can download the latest distribution of this library here.

Supposing the directory “/Test” on the FTP server we want to remove has the following structure:

Then the program would produce the following output:

Related Java FTP Tutorials:

• Determine if a directory or file exists on FTP server
• Java FTP create directory example
• Java FTP example - Change working directory
• Remove an empty directory on a FTP server
• Rename file or directory on FTP server

 

Other Java FTP Tutorials:

• Connect and login to a FTP server
• Java FTP list files and directories example
• Java FTP file download tutorial and example
• Java FTP file upload tutorial and example
• Java FTP delete file example
• Java FTP example - Search for files and directories
• How to upload a directory to a FTP server
• How to download a complete folder from a FTP server