I am trying to connect to solr using solrj. My solr instance runs in jetty and is protected with basic authentication. I found these links that contain relevant information.
You need to add the JAR solr-solrj-4.0.0.jar for HttpClientUtil.
Then use the below code:
HttpSolrServer solrServer = new HttpSolrServer("http://localhost:8080/solr/"+url);
HttpClientUtil.setBasicAuth((DefaultHttpClient) solrServer.getHttpClient(), "USERNAME", "PASSWORD");
That worked for me on Jdk 1.6 and tomcat 6