Q:

Java Proxy Authentication

I have a Java webapp, running in Tomcat 6, that loads RSS feeds from remote URLs. 
I use Rome to handle the RSS feeds and different formats for me.  The connection part looks like like that :
try{
  feedSource = new URL(rssObject.getAsset());
}catch(MalformedURLException mue){
  logger.error(...);
  throw mue;
}

try{
    URLConnection connection = feedSource.openConnection();
    feed = new SyndFeedInput().build(new XmlReader(connection));
}catch(Exception){handle...}

The code works fine, except at this new client, where they use a proxy. 
In order to use the proxy, I set the http.proxyHost and proxyPort system properties :
System.setProperty("http.proxyHost", proxyHost);
System.setProperty("http.proxyPort", proxyPort);
System.setProperty("https.proxyHost", proxyHost);
System.setProperty("https.proxyPort", proxyPort);

HTTP GET is made to the proxy alright, but now I get a HTTP 502 error (bad gateway or something similar). 
Analysing the HTTP exchange with Wireshark, I noticed that the proxy is requiring authentication.  It sends a HTTP 507.  Java is somehow trying to authenticate but it uses the wrong username and passwords.  It seems to use the host name as the username, as for the password I don't know. 
So I tried to implement the Authenticator method of specifying a username+password :
Authenticator.setDefault(new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                logger.info(MessageFormat.format("Generating PasswordAuthentitcation for proxy authentication, using username={0} and password={1}.",  username, password));
                return new PasswordAuthentication(username, password.toCharArray());
            }
        });

Now my problem is that it is ignored.  The getPasswordAuthentication method is never called.  I don't see the logging statement in the log file and using Wireshark I can see that it still uses the host name as the user name. 
Why ?  It seems that java somehow tries to authenticate by itself without consulting the Authenticator. 
The proxy seems to be a MS device that uses NTLM for authentication.  Is there some built-in mechanism in java to handle this ?  The machine on which the app runs is Win Server 2008 R2. 

A:

We did the same here for authenticating on a NTLM based proxy. 
The authentication on the proxy is actually a normal HTTP Basic Authentication. 
We used the following method:
protected URLConnection newURLConnection(URL pURL) throws IOException {
    URLConnection urlConnection = super.newURLConnection(pURL);

    String auth = new String(Base64.base64Encode(new String("username:password").getBytes()));
    auth = "Basic " + auth;
    urlConnection.setRequestProperty("Proxy-Connection","Keep-Alive");
    urlConnection.setRequestProperty("Proxy-Authorization",auth);
    return urlConnection;
}

That, together with the proxy jvm settings, did the trick. 
See http://en.wikipedia.org/wiki/Basic_access_authentication.