org.apache.lucene.search

Class Searcher

java.lang.Object

org.apache.lucene.search.Searcher

All Implemented Interfaces:

Remote, Searchable

Direct Known Subclasses:

IndexSearcher, MultiSearcher

public abstract class Searcher
extends Object
implements Searchable

An abstract base class for search implementations. Implements the main search methods.

Note that you can only access Hits from a Searcher as long as it is not yet closed, otherwise an IOException will be thrown.

Constructor Summary

Constructors

Constructor and Description
Searcher()

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	close() Frees resources associated with this Searcher.
protected Weight	createWeight(Query query) creates a weight for query
abstract Document	doc(int i) Expert: Returns the stored fields of document i.
abstract int	docFreq(Term term) Expert: Returns the number of documents containing term.
int[]	docFreqs(Term[] terms) Expert: For each term in the terms array, calculates the number of documents containing term.
Explanation	explain(Query query, int doc) Returns an Explanation that describes how doc scored against query.
abstract Explanation	explain(Weight weight, int doc) Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.
Similarity	getSimilarity() Expert: Return the Similarity implementation used by this Searcher.
abstract int	maxDoc() Expert: Returns one greater than the largest possible document number.
abstract Query	rewrite(Query query) Expert: called to re-write queries into primitive queries.
Hits	search(Query query) Returns the documents matching query.
Hits	search(Query query, Filter filter) Returns the documents matching query and filter.
void	search(Query query, Filter filter, HitCollector results) Lower-level search API.
TopDocs	search(Query query, Filter filter, int n) Expert: Low-level search implementation.
TopFieldDocs	search(Query query, Filter filter, int n, Sort sort) Expert: Low-level search implementation with arbitrary sorting.
Hits	search(Query query, Filter filter, Sort sort) Returns documents matching query and filter, sorted by sort.
void	search(Query query, HitCollector results) Lower-level search API.
Hits	search(Query query, Sort sort) Returns documents matching query sorted by sort.
abstract void	search(Weight weight, Filter filter, HitCollector results) Lower-level search API.
abstract TopDocs	search(Weight weight, Filter filter, int n) Expert: Low-level search implementation.
abstract TopFieldDocs	search(Weight weight, Filter filter, int n, Sort sort) Expert: Low-level search implementation with arbitrary sorting.
void	setSimilarity(Similarity similarity) Expert: Set the Similarity implementation used by this Searcher.

Methods inherited from class java.lang.Object

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

Constructor Detail

Searcher

public Searcher()

Method Detail

search

public final Hits search(Query query)
                  throws IOException

Returns the documents matching query.

Throws:

BooleanQuery.TooManyClauses

IOException

search

public Hits search(Query query,
          Filter filter)
            throws IOException

Returns the documents matching query and filter.

Throws:

BooleanQuery.TooManyClauses

IOException

search

public Hits search(Query query,
          Sort sort)
            throws IOException

Returns documents matching query sorted by sort.

Throws:

BooleanQuery.TooManyClauses

IOException

search

public Hits search(Query query,
          Filter filter,
          Sort sort)
            throws IOException

Returns documents matching query and filter, sorted by sort.

Throws:

BooleanQuery.TooManyClauses

IOException

search

public TopFieldDocs search(Query query,
                  Filter filter,
                  int n,
                  Sort sort)
                    throws IOException

Expert: Low-level search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.

Applications should usually call search(Query,Filter,Sort) instead.

Specified by:

search in interface Searchable

Throws:

BooleanQuery.TooManyClauses

IOException

search

public void search(Query query,
          HitCollector results)
            throws IOException

Lower-level search API.

HitCollector.collect(int,float) is called for every non-zero scoring document.

Applications should only use this if they need all of the matching documents. The high-level search API (search(Query)) is usually more efficient, as it skips non-high-scoring hits.

Note: The score passed to this method is a raw score. In other words, the score will not necessarily be a float whose value is between 0 and 1.

Throws:

BooleanQuery.TooManyClauses

IOException

search

public void search(Query query,
          Filter filter,
          HitCollector results)
            throws IOException

Lower-level search API.

HitCollector.collect(int,float) is called for every non-zero scoring document.
HitCollector-based access to remote indexes is discouraged.

Applications should only use this if they need all of the matching documents. The high-level search API (search(Query)) is usually more efficient, as it skips non-high-scoring hits.

Specified by:

search in interface Searchable

Parameters:

query - to match documents

filter - if non-null, a bitset used to eliminate some documents

results - to receive hits

Throws:

BooleanQuery.TooManyClauses

IOException

search

public TopDocs search(Query query,
             Filter filter,
             int n)
               throws IOException

Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null.

Called by Hits.

Applications should usually call search(Query) or search(Query,Filter) instead.

Specified by:

search in interface Searchable

Throws:

BooleanQuery.TooManyClauses

IOException

explain

public Explanation explain(Query query,
                  int doc)
                    throws IOException

Returns an Explanation that describes how doc scored against query.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Specified by:

explain in interface Searchable

Throws:

IOException

setSimilarity

public void setSimilarity(Similarity similarity)

Expert: Set the Similarity implementation used by this Searcher.

See Also:

Similarity.setDefault(Similarity)

getSimilarity

public Similarity getSimilarity()

Expert: Return the Similarity implementation used by this Searcher.

This defaults to the current value of Similarity.getDefault().

createWeight

protected Weight createWeight(Query query)
                       throws IOException

creates a weight for query

Returns:

new weight

Throws:

IOException

docFreqs

public int[] docFreqs(Term[] terms)
               throws IOException

Description copied from interface: Searchable

Expert: For each term in the terms array, calculates the number of documents containing term. Returns an array with these document frequencies. Used to minimize number of remote calls.

Specified by:

docFreqs in interface Searchable

Throws:

IOException

search

public abstract void search(Weight weight,
          Filter filter,
          HitCollector results)
                     throws IOException

Description copied from interface: Searchable

Lower-level search API.

HitCollector.collect(int,float) is called for every non-zero scoring document.
HitCollector-based access to remote indexes is discouraged.

Applications should only use this if they need all of the matching documents. The high-level search API (search(Query)) is usually more efficient, as it skips non-high-scoring hits.

Specified by:

search in interface Searchable

Parameters:

weight - to match documents

filter - if non-null, a bitset used to eliminate some documents

results - to receive hits

Throws:

IOException

close

public abstract void close()
                    throws IOException

Description copied from interface: Searchable

Frees resources associated with this Searcher. Be careful not to call this method while you are still using objects like Hits.

Specified by:

close in interface Searchable

Throws:

IOException

docFreq

public abstract int docFreq(Term term)
                     throws IOException

Description copied from interface: Searchable

Expert: Returns the number of documents containing term. Called by search code to compute term weights.

Specified by:

docFreq in interface Searchable

Throws:

IOException

See Also:

IndexReader.docFreq(Term)

maxDoc

public abstract int maxDoc()
                    throws IOException

Description copied from interface: Searchable

Expert: Returns one greater than the largest possible document number. Called by search code to compute term weights.

Specified by:

maxDoc in interface Searchable

Throws:

IOException

See Also:

IndexReader.maxDoc()

search

public abstract TopDocs search(Weight weight,
             Filter filter,
             int n)
                        throws IOException

Description copied from interface: Searchable

Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null.

Called by Hits.

Applications should usually call search(Query) or search(Query,Filter) instead.

Specified by:

search in interface Searchable

Throws:

IOException

doc

public abstract Document doc(int i)
                      throws IOException

Description copied from interface: Searchable

Expert: Returns the stored fields of document i. Called by HitCollector implementations.

Specified by:

doc in interface Searchable

Throws:

IOException

See Also:

IndexReader.document(int)

rewrite

public abstract Query rewrite(Query query)
                       throws IOException

Description copied from interface: Searchable

Expert: called to re-write queries into primitive queries.

Specified by:

rewrite in interface Searchable

Throws:

IOException

explain

public abstract Explanation explain(Weight weight,
                  int doc)
                             throws IOException

Description copied from interface: Searchable

Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Applications should call explain(Query, int).

Specified by:

explain in interface Searchable

Throws:

IOException

search

public abstract TopFieldDocs search(Weight weight,
                  Filter filter,
                  int n,
                  Sort sort)
                             throws IOException

Description copied from interface: Searchable

Expert: Low-level search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.

Applications should usually call search(Query,Filter,Sort) instead.

Specified by:

search in interface Searchable

Throws:

IOException