Use lucene index in java application - lucene

Question

Recently i stared working on solr. I have created index in solr and i want to query on it through my java application. I don't want to use solr.war in my application. How can i use it through solrj api or lucene java api? My thinking is to add those index in project context and use it. I gone through some examples/tutorials but did not find any on how to work with already created index. Please tell me a proper solution for it or any link specifying the solution will be appreciated.

Answer 1

You can use Lucene apis to create/update and search on an index.
As solr is based on lucene, the underlying index is the lucene index.
Lucene exposes classes as IndexWriter and IndexSearcher, which would help you interact with index.
Example for searching over an solr/lucene index -
Directory index = FSDirectory.open(new File("/path/to/index"));
IndexSearcher searcher = new IndexSearcher(index, true);
TopScoreDocCollector collector = TopScoreDocCollector.create(10, true);
searcher.search(q, collector);
ScoreDoc[] hits = collector.topDocs().scoreDocs;
Should be able to find examples on this.

Answer 2

Yes, you can use a Solr-created index with Lucene, there's nothing particular about it because Solr itself uses Lucene. So all Lucene documentation applies unchanged.
Or if you don't want to use Solr as a server you can use it embedded in your Java application.

Answer 3

I made it this way..
String realPath = request.getRealPath("/");
StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
Directory index = FSDirectory.open(new File(realPath+"/index"));
IndexSearcher indexSearcher = new IndexSearcher(index, true);
TopScoreDocCollector collector = TopScoreDocCollector.create(2000, true);
QueryParser query = new QueryParser(Version.LUCENE_CURRENT, "name", analyzer);
Query q = null;
try {
q = query.parse("*:*");
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
indexSearcher.search(q, collector);
ScoreDoc[] scoreDoc = collector.topDocs().scoreDocs;