private Collection<? extends CRL> getCRLs(String crlf) throws IOException, CRLException,
			CertificateException {

		File crlFile = new File(crlf);
		if (!crlFile.isAbsolute()) {
			crlFile = new File(System.getProperty("catalina.base"), crlf);
		}
		Collection<? extends CRL> crls = null;
		InputStream is = null;
		try {
			CertificateFactory cf = CertificateFactory.getInstance("X.509");
			is = new FileInputStream(crlFile);
			crls = cf.generateCRLs(is);
		} catch (IOException iex) {
			throw iex;
		} catch (CRLException crle) {
			throw crle;
		} catch (CertificateException ce) {
			throw ce;
		} finally {
			if (is != null) {
				try {
					is.close();
				} catch (Exception ex) {
				}
			}
		}
		return crls;
	}