Class BoostQuery


  • public final class BoostQuery
    extends Query
    A Query wrapper that allows to give a boost to the wrapped query. Boost values that are less than one will give less importance to this query compared to other ones while values that are greater than one will give more importance to the scores returned by this query.

    More complex boosts can be applied by using FunctionScoreQuery in the lucene-queries module

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private float boost  
      private Query query  
    • Constructor Summary

      Constructors 
      Constructor Description
      BoostQuery​(Query query, float boost)
      Sole constructor: wrap query in such a way that the produced scores will be boosted by boost.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Weight createWeight​(IndexSearcher searcher, ScoreMode scoreMode, float boost)
      Expert: Constructs an appropriate Weight implementation for this query.
      boolean equals​(java.lang.Object other)
      Override and implement query instance equivalence properly in a subclass.
      private boolean equalsTo​(BoostQuery other)  
      float getBoost()
      Return the applied boost.
      Query getQuery()
      Return the wrapped Query.
      int hashCode()
      Override and implement query hash code properly in a subclass.
      Query rewrite​(IndexReader reader)
      Expert: called to re-write queries into primitive queries.
      java.lang.String toString​(java.lang.String field)
      Prints a query to a string, with field assumed to be the default field and omitted.
      void visit​(QueryVisitor visitor)
      Recurse through the query tree, visiting any child queries
      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait
    • Field Detail

      • query

        private final Query query
      • boost

        private final float boost
    • Constructor Detail

      • BoostQuery

        public BoostQuery​(Query query,
                          float boost)
        Sole constructor: wrap query in such a way that the produced scores will be boosted by boost.
    • Method Detail

      • getQuery

        public Query getQuery()
        Return the wrapped Query.
      • getBoost

        public float getBoost()
        Return the applied boost.
      • equals

        public boolean equals​(java.lang.Object other)
        Description copied from class: Query
        Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly.

        Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.

        Specified by:
        equals in class Query
        See Also:
        Query.sameClassAs(Object), Query.classHash()
      • equalsTo

        private boolean equalsTo​(BoostQuery other)
      • hashCode

        public int hashCode()
        Description copied from class: Query
        Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.
        Specified by:
        hashCode in class Query
        See Also:
        Query.equals(Object)
      • rewrite

        public Query rewrite​(IndexReader reader)
                      throws java.io.IOException
        Description copied from class: Query
        Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

        Callers are expected to call rewrite multiple times if necessary, until the rewritten query is the same as the original query.

        Overrides:
        rewrite in class Query
        Throws:
        java.io.IOException
        See Also:
        IndexSearcher.rewrite(Query)
      • visit

        public void visit​(QueryVisitor visitor)
        Description copied from class: Query
        Recurse through the query tree, visiting any child queries
        Specified by:
        visit in class Query
        Parameters:
        visitor - a QueryVisitor to be called by each query in the tree
      • toString

        public java.lang.String toString​(java.lang.String field)
        Description copied from class: Query
        Prints a query to a string, with field assumed to be the default field and omitted.
        Specified by:
        toString in class Query
      • createWeight

        public Weight createWeight​(IndexSearcher searcher,
                                   ScoreMode scoreMode,
                                   float boost)
                            throws java.io.IOException
        Description copied from class: Query
        Expert: Constructs an appropriate Weight implementation for this query.

        Only implemented by primitive queries, which re-write to themselves.

        Overrides:
        createWeight in class Query
        scoreMode - How the produced scorers will be consumed.
        boost - The boost that is propagated by the parent queries.
        Throws:
        java.io.IOException