/**
* 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 bool 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.logger().fine(message);
return(false);
}
catch (Exception e)
{
String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName);
Logging.logger().info(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.logger().info(message);
}
finally
{
if (connection != null && connection is HttpURLConnection)
{
((HttpURLConnection)connection).disconnect();
}
}
return(false);
}
