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Lucene example source code file (MultiFieldQueryParser.java)

This example Lucene source code file (MultiFieldQueryParser.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

analyzer, arraylist, booleanclause, booleanquery, booleanquery, list, override, parseexception, parseexception, query, query, queryparser, string, string, util

The Lucene MultiFieldQueryParser.java source code

package org.apache.lucene.queryParser;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.MultiPhraseQuery;
import org.apache.lucene.search.PhraseQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.util.Version;

/**
 * A QueryParser which constructs queries to search multiple fields.
 *
 * @version $Revision: 965592 $
 */
public class MultiFieldQueryParser extends QueryParser
{
  protected String[] fields;
  protected Map<String,Float> boosts;

  /**
   * Creates a MultiFieldQueryParser. 
   * Allows passing of a map with term to Boost, and the boost to apply to each term.
   *
   * <p>It will, when parse(String query)
   * is called, construct a query like this (assuming the query consists of
   * two terms and you specify the two fields <code>title and body):

* * <code> * (title:term1 body:term1) (title:term2 body:term2) * </code> * * <p>When setDefaultOperator(AND_OPERATOR) is set, the result will be:

* * <code> * +(title:term1 body:term1) +(title:term2 body:term2) * </code> * * <p>When you pass a boost (title=>5 body=>10) you can get

* * <code> * +(title:term1^5.0 body:term1^10.0) +(title:term2^5.0 body:term2^10.0) * </code> * * <p>In other words, all the query's terms must appear, but it doesn't matter in * what fields they appear.</p> */ public MultiFieldQueryParser(Version matchVersion, String[] fields, Analyzer analyzer, Map<String,Float> boosts) { this(matchVersion, fields, analyzer); this.boosts = boosts; } /** * Creates a MultiFieldQueryParser. * * <p>It will, when parse(String query) * is called, construct a query like this (assuming the query consists of * two terms and you specify the two fields <code>title and body):

* * <code> * (title:term1 body:term1) (title:term2 body:term2) * </code> * * <p>When setDefaultOperator(AND_OPERATOR) is set, the result will be:

* * <code> * +(title:term1 body:term1) +(title:term2 body:term2) * </code> * * <p>In other words, all the query's terms must appear, but it doesn't matter in * what fields they appear.</p> */ public MultiFieldQueryParser(Version matchVersion, String[] fields, Analyzer analyzer) { super(matchVersion, null, analyzer); this.fields = fields; } @Override protected Query getFieldQuery(String field, String queryText, int slop) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { Query q = super.getFieldQuery(fields[i], queryText, true); if (q != null) { //If the user passes a map of boosts if (boosts != null) { //Get the boost from the map and apply them Float boost = boosts.get(fields[i]); if (boost != null) { q.setBoost(boost.floatValue()); } } applySlop(q,slop); clauses.add(new BooleanClause(q, BooleanClause.Occur.SHOULD)); } } if (clauses.size() == 0) // happens for stopwords return null; return getBooleanQuery(clauses, true); } Query q = super.getFieldQuery(field, queryText, true); applySlop(q,slop); return q; } private void applySlop(Query q, int slop) { if (q instanceof PhraseQuery) { ((PhraseQuery) q).setSlop(slop); } else if (q instanceof MultiPhraseQuery) { ((MultiPhraseQuery) q).setSlop(slop); } } @Override protected Query getFieldQuery(String field, String queryText, boolean quoted) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { Query q = super.getFieldQuery(fields[i], queryText, quoted); if (q != null) { //If the user passes a map of boosts if (boosts != null) { //Get the boost from the map and apply them Float boost = boosts.get(fields[i]); if (boost != null) { q.setBoost(boost.floatValue()); } } clauses.add(new BooleanClause(q, BooleanClause.Occur.SHOULD)); } } if (clauses.size() == 0) // happens for stopwords return null; return getBooleanQuery(clauses, true); } Query q = super.getFieldQuery(field, queryText, quoted); return q; } @Override protected Query getFuzzyQuery(String field, String termStr, float minSimilarity) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { clauses.add(new BooleanClause(getFuzzyQuery(fields[i], termStr, minSimilarity), BooleanClause.Occur.SHOULD)); } return getBooleanQuery(clauses, true); } return super.getFuzzyQuery(field, termStr, minSimilarity); } @Override protected Query getPrefixQuery(String field, String termStr) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { clauses.add(new BooleanClause(getPrefixQuery(fields[i], termStr), BooleanClause.Occur.SHOULD)); } return getBooleanQuery(clauses, true); } return super.getPrefixQuery(field, termStr); } @Override protected Query getWildcardQuery(String field, String termStr) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { clauses.add(new BooleanClause(getWildcardQuery(fields[i], termStr), BooleanClause.Occur.SHOULD)); } return getBooleanQuery(clauses, true); } return super.getWildcardQuery(field, termStr); } @Override protected Query getRangeQuery(String field, String part1, String part2, boolean inclusive) throws ParseException { if (field == null) { List<BooleanClause> clauses = new ArrayList(); for (int i = 0; i < fields.length; i++) { clauses.add(new BooleanClause(getRangeQuery(fields[i], part1, part2, inclusive), BooleanClause.Occur.SHOULD)); } return getBooleanQuery(clauses, true); } return super.getRangeQuery(field, part1, part2, inclusive); } /** * Parses a query which searches on the fields specified. * <p> * If x fields are specified, this effectively constructs: * <pre> * <code> * (field1:query1) (field2:query2) (field3:query3)...(fieldx:queryx) * </code> * </pre> * @param matchVersion Lucene version to match; this is passed through to QueryParser. * @param queries Queries strings to parse * @param fields Fields to search on * @param analyzer Analyzer to use * @throws ParseException if query parsing fails * @throws IllegalArgumentException if the length of the queries array differs * from the length of the fields array */ public static Query parse(Version matchVersion, String[] queries, String[] fields, Analyzer analyzer) throws ParseException { if (queries.length != fields.length) throw new IllegalArgumentException("queries.length != fields.length"); BooleanQuery bQuery = new BooleanQuery(); for (int i = 0; i < fields.length; i++) { QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer); Query q = qp.parse(queries[i]); if (q!=null && // q never null, just being defensive (!(q instanceof BooleanQuery) || ((BooleanQuery)q).getClauses().length>0)) { bQuery.add(q, BooleanClause.Occur.SHOULD); } } return bQuery; } /** * Parses a query, searching on the fields specified. * Use this if you need to specify certain fields as required, * and others as prohibited. * <p>
   * Usage:
   * <code>
   * String[] fields = {"filename", "contents", "description"};
   * BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
   *                BooleanClause.Occur.MUST,
   *                BooleanClause.Occur.MUST_NOT};
   * MultiFieldQueryParser.parse("query", fields, flags, analyzer);
   * </code>
   * </pre>
   *<p>
   * The code above would construct a query:
   * <pre>
   * <code>
   * (filename:query) +(contents:query) -(description:query)
   * </code>
   * </pre>
   *
   * @param matchVersion Lucene version to match; this is passed through to QueryParser.
   * @param query Query string to parse
   * @param fields Fields to search on
   * @param flags Flags describing the fields
   * @param analyzer Analyzer to use
   * @throws ParseException if query parsing fails
   * @throws IllegalArgumentException if the length of the fields array differs
   *  from the length of the flags array
   */
  public static Query parse(Version matchVersion, String query, String[] fields,
      BooleanClause.Occur[] flags, Analyzer analyzer) throws ParseException {
    if (fields.length != flags.length)
      throw new IllegalArgumentException("fields.length != flags.length");
    BooleanQuery bQuery = new BooleanQuery();
    for (int i = 0; i < fields.length; i++) {
      QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer);
      Query q = qp.parse(query);
      if (q!=null && // q never null, just being defensive 
          (!(q instanceof BooleanQuery) || ((BooleanQuery)q).getClauses().length>0)) {
        bQuery.add(q, flags[i]);
      }
    }
    return bQuery;
  }

  /**
   * Parses a query, searching on the fields specified.
   * Use this if you need to specify certain fields as required,
   * and others as prohibited.
   * <p>
   * Usage:
   * <code>
   * String[] query = {"query1", "query2", "query3"};
   * String[] fields = {"filename", "contents", "description"};
   * BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
   *                BooleanClause.Occur.MUST,
   *                BooleanClause.Occur.MUST_NOT};
   * MultiFieldQueryParser.parse(query, fields, flags, analyzer);
   * </code>
   * </pre>
   *<p>
   * The code above would construct a query:
   * <pre>
   * <code>
   * (filename:query1) +(contents:query2) -(description:query3)
   * </code>
   * </pre>
   *
   * @param matchVersion Lucene version to match; this is passed through to QueryParser.
   * @param queries Queries string to parse
   * @param fields Fields to search on
   * @param flags Flags describing the fields
   * @param analyzer Analyzer to use
   * @throws ParseException if query parsing fails
   * @throws IllegalArgumentException if the length of the queries, fields,
   *  and flags array differ
   */
  public static Query parse(Version matchVersion, String[] queries, String[] fields, BooleanClause.Occur[] flags,
      Analyzer analyzer) throws ParseException
  {
    if (!(queries.length == fields.length && queries.length == flags.length))
      throw new IllegalArgumentException("queries, fields, and flags array have have different length");
    BooleanQuery bQuery = new BooleanQuery();
    for (int i = 0; i < fields.length; i++)
    {
      QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer);
      Query q = qp.parse(queries[i]);
      if (q!=null && // q never null, just being defensive
          (!(q instanceof BooleanQuery) || ((BooleanQuery)q).getClauses().length>0)) {
        bQuery.add(q, flags[i]);
      }
    }
    return bQuery;
  }

}

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