Get matched terms from Lucene query

Question

Given a Lucene search query like: +(letter:A letter:B letter:C) +(style:Capital), how can I tell which of the three letters actually matched any given document?

Answer 1

Although the sample is in c#, Lucene APIs are very similar(some upper/lower case differences). I don't think it would be hard to translate to java.

This is the usage

List terms = new List();    //will be filled with non-matched terms
List hitTerms = new List(); //will be filled with matched terms
GetHitTerms(query, searcher,docId, hitTerms,terms);

And here is the method

void GetHitTerms(Query query,IndexSearcher searcher,int docId,List hitTerms,Listrest)
{
    if (query is TermQuery)
    {
        if (searcher.Explain(query, docId).IsMatch() == true) 
            hitTerms.Add((query as TermQuery).GetTerm());
        else
            rest.Add((query as TermQuery).GetTerm());
        return;
    }

    if (query is BooleanQuery)
    {
        BooleanClause[] clauses = (query as BooleanQuery).GetClauses();
        if (clauses == null) return;

        foreach (BooleanClause bc in clauses)
        {
            GetHitTerms(bc.GetQuery(), searcher, docId,hitTerms,rest);
        }
        return;
    }

    if (query is MultiTermQuery)
    {
        if (!(query is FuzzyQuery)) //FuzzQuery doesn't support SetRewriteMethod
            (query as MultiTermQuery).SetRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE);

        GetHitTerms(query.Rewrite(searcher.GetIndexReader()), searcher, docId,hitTerms,rest);
    }
}