org.apache.lucene.search.highlight

Class QueryTermScorer

  • All Implemented Interfaces:
    Scorer


    public class QueryTermScorer
    extends Object
    implements Scorer
    Scorer implementation which scores text fragments by the number of unique query terms found. This class uses the QueryTermExtractor class to process determine the query terms and their boosts to be used.
    • Constructor Detail

      • QueryTermScorer

        public QueryTermScorer(Query query)
        Parameters:
        query - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
      • QueryTermScorer

        public QueryTermScorer(Query query,
                               String fieldName)
        Parameters:
        query - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
        fieldName - the Field name which is used to match Query terms
      • QueryTermScorer

        public QueryTermScorer(Query query,
                               IndexReader reader,
                               String fieldName)
        Parameters:
        query - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
        reader - used to compute IDF which can be used to a) score selected fragments better b) use graded highlights eg set font color intensity
        fieldName - the field on which Inverse Document Frequency (IDF) calculations are based
    • Method Detail

      • init

        public TokenStream init(TokenStream tokenStream)
        Description copied from interface: Scorer
        Called to init the Scorer with a TokenStream. You can grab references to the attributes you are interested in here and access them from Scorer.getTokenScore().
        Specified by:
        init in interface Scorer
        Parameters:
        tokenStream - the TokenStream that will be scored.
        Returns:
        either a TokenStream that the Highlighter should continue using (eg if you read the tokenSream in this method) or null to continue using the same TokenStream that was passed in.
      • startFragment

        public void startFragment(TextFragment newFragment)
        Description copied from interface: Scorer
        Called when a new fragment is started for consideration.
        Specified by:
        startFragment in interface Scorer
        Parameters:
        newFragment - the fragment that will be scored next
      • getTokenScore

        public float getTokenScore()
        Description copied from interface: Scorer
        Called for each token in the current fragment. The Highlighter will increment the TokenStream passed to init on every call.
        Specified by:
        getTokenScore in interface Scorer
        Returns:
        a score which is passed to the Highlighter class to influence the mark-up of the text (this return value is NOT used to score the fragment)
      • getMaxTermWeight

        public float getMaxTermWeight()
        Returns:
        The highest weighted term (useful for passing to GradientFormatter to set top end of coloring scale.