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