Вы можете использовать java.net
API:
URL url =
new URL("ftp://user:pass@ftp.example.com/file.zip");
URLConnection connection = url.openConnection();
BufferedInputStream in =
new BufferedInputStream(connection.getInputStream());
FileOutputStream out =
new FileOutputStream("file.zip");
int read = 0;
byte[] data = new byte[1024];
while ((read = in.read(data)) >= 0) {
out.write(data, 0, read);
}
out.close();
in.close();