/** * Determine if a host is reachable by attempting to resolve the host name, and then attempting to * open a connection. * * @param hostName Name of the host to connect to. * @return {@code true} if a the host is reachable, {@code false} if the host name cannot be * resolved, or if opening a connection to the host fails. */ protected static boolean isHostReachable(String hostName) { try { // Assume host is unreachable if we can't get its dns entry without getting an exception //noinspection ResultOfMethodCallIgnored InetAddress.getByName(hostName); } catch (UnknownHostException e) { String message = Logging.getMessage("NetworkStatus.UnreachableTestHost", hostName); Logging.verbose(message); return false; } catch (Exception e) { String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName); Logging.verbose(message); return false; } // Was able to get internet address, but host still might not be reachable because the address // might have been // cached earlier when it was available. So need to try something else. URLConnection connection = null; try { URL url = new URL("http://" + hostName); Proxy proxy = WWIO.configureProxy(); if (proxy != null) connection = url.openConnection(proxy); else connection = url.openConnection(); connection.setConnectTimeout(2000); connection.setReadTimeout(2000); String ct = connection.getContentType(); if (ct != null) return true; } catch (IOException e) { String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName); Logging.info(message); } finally { if (connection instanceof HttpURLConnection) ((HttpURLConnection) connection).disconnect(); } return false; }