HttpClient Authentication Doument: 
http://hc.apache.org/httpclient-3.x/authentication.html

HttpClient支持使用代理服务器以及身份认证

1、代理服务器的设置很简单： 
HttpClient client = new HttpClient(); 
client.getHostConfiguration().setProxy(host, port);

2、身份验证： 
HttpClient client = new HttpClient(); 
client.getParams().setAuthenticationPreemptive(true); 
Credentials defaultcreds = new UsernamePasswordCredentials("username", "password"); 
client.getState().setCredentials(AuthScope.ANY, defaultcreds);