In Java when does a URL connection close?

try {
  URL url = new URL("http://foo.bar");
  URLConnection conn = url.openConnection();
  // use the connection
}
catch (Exception e) {
  // any clean up here?
}

/**
 * rewriting for static resources
 *
 * @param path the path, with the leading /
 */
public static String stat(final String path) {
    try {
        final URL resource = ServletActionContext.getServletContext().getResource(path);
        final URLConnection connection = resource.openConnection();
        final long l = connection.getLastModified();
        return STATIC_CONTENT_PREFIX + path + "?" + l;
    } catch (MalformedURLException e) {
        throw new RuntimeException(e);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}