org.apache.lucene.search

Class ConstantScoreQuery

java.lang.Object

org.apache.lucene.search.Query

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

Nested Classes

Modifier and Type	Class and Description
protected class	ConstantScoreQuery.ConstantScorer
protected class	ConstantScoreQuery.ConstantWeight

Field Summary

Fields

Modifier and Type	Field and Description
protected Filter	filter
protected Query	query

Constructor Summary

Constructors

Constructor and Description
ConstantScoreQuery(Filter filter) Wraps a Filter as a Query.
ConstantScoreQuery(Query query) Strips off scores from the passed in Query.

Method Summary

Methods

Modifier and Type	Method and Description
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:

• If the query was created by the parser, the printed representation may not be exactly what was parsed. For example, characters that need to be escaped will be represented without the required backslash.
• Some of the more complicated queries (e.g. span queries) don't have a representation that can be parsed by QueryParser.

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