Apache HttpClient 4.1 - Proxy Authentication

For Basic-Auth it looks like this:

DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getCredentialsProvider().setCredentials(
    new AuthScope("PROXY HOST", 8080),
    new UsernamePasswordCredentials("username", "password"));

HttpHost targetHost = new HttpHost("TARGET HOST", 443, "https");
HttpHost proxy = new HttpHost("PROXY HOST", 8080);

httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);

AFAIK NTLM is not supported out of the box. But you might be able to manage that using NTCredentials and maybe overloading DefaultProxyAuthenticationHandler.

For anyone looking for the answer for 4.3...its fairly new and their example didn't use the new HttpClientBuilder...so this is how I implemented this in that version:

NTCredentials ntCreds = new NTCredentials(ntUsername, ntPassword,localMachineName, domainName );

CredentialsProvider credsProvider = new BasicCredentialsProvider();
credsProvider.setCredentials( new AuthScope(proxyHost,proxyPort), ntCreds );
HttpClientBuilder clientBuilder = HttpClientBuilder.create();

clientBuilder.useSystemProperties();
clientBuilder.setProxy(new HttpHost(pxInfo.getProxyURL(), pxInfo.getProxyPort()));
clientBuilder.setDefaultCredentialsProvider(credsProvider);
clientBuilder.setProxyAuthenticationStrategy(new ProxyAuthenticationStrategy());

CloseableHttpClient client = clientBuilder.build();