title: Resume a Java FTP file download
body: <p>I'm developing, in Java, an application that has to download from a server to client some very large files. So far I'm using the apache commons-net:</p>
  
  <pre><code>FileOutputStream out = new FileOutputStream(file);
  client.retrieveFile(filename, out);
  </code></pre>
  
  <p>The connection commonly fails before the client finishes downloading the file. I need a way to resume the download of the file from the point where the connection failed, without downloading the whole file again, is it possible?</p>