org.apache.lucene.search
Class ConstantScoreQuery

java.lang.Object
  extended by org.apache.lucene.search.Query
      extended by org.apache.lucene.search.ConstantScoreQuery
All Implemented Interfaces:
Serializable, Cloneable

public class ConstantScoreQuery
extends Query

A query that wraps another query or a filter and simply returns a constant score equal to the query boost for every document that matches the filter or query. For queries it therefore simply strips of all scores and returns a constant one.

NOTE: if the wrapped filter is an instance of CachingWrapperFilter, you'll likely want to enforce deletions in the filter (using either CachingWrapperFilter.DeletesMode.RECACHE or CachingWrapperFilter.DeletesMode.DYNAMIC).

See Also:
Serialized Form

Nested Class Summary
protected  class ConstantScoreQuery.ConstantScorer
           
protected  class ConstantScoreQuery.ConstantWeight
           
 
Field Summary
protected  Filter filter
           
protected  Query query
           
 
Constructor Summary
ConstantScoreQuery(Filter filter)
          Wraps a Filter as a Query.
ConstantScoreQuery(Query query)
          Strips off scores from the passed in Query.
 
Method Summary
 Weight createWeight(Searcher searcher)
          Expert: Constructs an appropriate Weight implementation for this query.
 boolean equals(Object o)
           
 void extractTerms(Set<Term> terms)
          Expert: adds all terms occurring in this query to the terms set.
 Filter getFilter()
          Returns the encapsulated filter, returns null if a query is wrapped.
 Query getQuery()
          Returns the encapsulated query, returns null if a filter is wrapped.
 int hashCode()
           
 Query rewrite(IndexReader reader)
          Expert: called to re-write queries into primitive queries.
 String toString(String field)
          Prints a query to a string, with field assumed to be the default field and omitted.
 
Methods inherited from class org.apache.lucene.search.Query
clone, combine, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

filter

protected final Filter filter

query

protected final Query query
Constructor Detail

ConstantScoreQuery

public ConstantScoreQuery(Query query)
Strips off scores from the passed in Query. The hits will get a constant score dependent on the boost factor of this query.


ConstantScoreQuery

public ConstantScoreQuery(Filter filter)
Wraps a Filter as a Query. The hits will get a constant score dependent on the boost factor of this query. If you simply want to strip off scores from a Query, no longer use new ConstantScoreQuery(new QueryWrapperFilter(query)), instead use ConstantScoreQuery(Query)!

Method Detail

getFilter

public Filter getFilter()
Returns the encapsulated filter, returns null if a query is wrapped.


getQuery

public Query getQuery()
Returns the encapsulated query, returns null if a filter is wrapped.


rewrite

public Query rewrite(IndexReader reader)
              throws 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.

Overrides:
rewrite in class Query
Throws:
IOException

extractTerms

public void extractTerms(Set<Term> terms)
Description copied from class: Query
Expert: adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten form.

Overrides:
extractTerms in class Query

createWeight

public Weight createWeight(Searcher searcher)
                    throws 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
Throws:
IOException

toString

public String toString(String field)
Description copied from class: Query
Prints a query to a string, with field assumed to be the default field and omitted.

The representation used is one that is supposed to be readable by QueryParser. However, there are the following limitations:

Specified by:
toString in class Query

equals

public boolean equals(Object o)
Overrides:
equals in class Query

hashCode

public int hashCode()
Overrides:
hashCode in class Query


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