org.apache.lucene.search
Class Query

java.lang.Object
  org.apache.lucene.search.Query

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

BooleanQuery, BoostingQuery, ConstantScoreQuery, ConstantScoreRangeQuery, CustomScoreQuery, DisjunctionMaxQuery, FilteredQuery, FuzzyLikeThisQuery, MatchAllDocsQuery, MoreLikeThisQuery, MultiPhraseQuery, MultiTermQuery, PhraseQuery, PrefixQuery, RangeQuery, SpanQuery, TermQuery, ValueSourceQuery

public abstract class Query
extends Object
implements Serializable, Cloneable

The abstract base class for queries.

Instantiable subclasses are:

• TermQuery
• MultiTermQuery
• BooleanQuery
• WildcardQuery
• PhraseQuery
• PrefixQuery
• MultiPhraseQuery
• FuzzyQuery
• RangeQuery
• SpanQuery

A parser for queries is contained in:

• QueryParser

See Also:

Serialized Form

Constructor Summary

Query()

Method Summary

Object	clone() Returns a clone of this query.
Query	combine(Query[] queries) Expert: called when re-writing queries under MultiSearcher.
protected Weight	createWeight(Searcher searcher) Expert: Constructs an appropriate Weight implementation for this query.
void	extractTerms(Set terms) Expert: adds all terms occuring in this query to the terms set.
float	getBoost() Gets the boost for this clause.
Similarity	getSimilarity(Searcher searcher) Expert: Returns the Similarity implementation to be used for this query.
static Query	mergeBooleanQueries(Query[] queries) Expert: merges the clauses of a set of BooleanQuery's into a single BooleanQuery.
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
void	setBoost(float b) Sets the boost for this query clause to b.
String	toString() Prints a query to a string.
abstract String	toString(String field) Prints a query to a string, with field assumed to be the default field and omitted.
Weight	weight(Searcher searcher) Expert: Constructs and initializes a Weight for a top-level query.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Query

public Query()

Method Detail

setBoost

public void setBoost(float b)

Sets the boost for this query clause to b. Documents matching this clause will (in addition to the normal weightings) have their score multiplied by b.

getBoost

public float getBoost()

Gets the boost for this clause. Documents matching this clause will (in addition to the normal weightings) have their score multiplied by b. The boost is 1.0 by default.

toString

public abstract String toString(String field)

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.

toString

public String toString()

Prints a query to a string.

Overrides:

toString in class Object

createWeight

protected Weight createWeight(Searcher searcher)
                       throws IOException

Expert: Constructs an appropriate Weight implementation for this query.

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

Throws:

IOException

weight

public Weight weight(Searcher searcher)
              throws IOException

Expert: Constructs and initializes a Weight for a top-level query.

Throws:

IOException

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

Throws:

IOException

combine

public Query combine(Query[] queries)

Expert: called when re-writing queries under MultiSearcher. Create a single query suitable for use by all subsearchers (in 1-1 correspondence with queries). This is an optimization of the OR of all queries. We handle the common optimization cases of equal queries and overlapping clauses of boolean OR queries (as generated by MultiTermQuery.rewrite() and RangeQuery.rewrite()). Be careful overriding this method as queries[0] determines which method will be called and is not necessarily of the same type as the other queries.

extractTerms

public void extractTerms(Set terms)

Expert: adds all terms occuring in this query to the terms set. Only works if this query is in its rewritten form.

Throws:

UnsupportedOperationException - if this query is not yet rewritten

mergeBooleanQueries

public static Query mergeBooleanQueries(Query[] queries)

Expert: merges the clauses of a set of BooleanQuery's into a single BooleanQuery.

A utility for use by combine(Query[]) implementations.

getSimilarity

public Similarity getSimilarity(Searcher searcher)

Expert: Returns the Similarity implementation to be used for this query. Subclasses may override this method to specify their own Similarity implementation, perhaps one that delegates through that of the Searcher. By default the Searcher's Similarity implementation is returned.

clone

public Object clone()

Returns a clone of this query.

Overrides:

clone in class Object