Lucene example source code file (FieldsQuery.java)

This example Lucene source code file (FieldsQuery.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

arraylist, fieldsquery, fieldsquery, iterator, list, list, or, orquery, override, srndquery, srndquery, string, string, stringbuilder, util

The Lucene FieldsQuery.java source code

package org.apache.lucene.queryParser.surround.query;
/**
 * 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.Iterator;

import org.apache.lucene.search.Query;

public class FieldsQuery extends SrndQuery { /* mostly untested */
  private SrndQuery q;
  private List<String> fieldNames;
  private final char fieldOp;
  private final String OrOperatorName = "OR"; /* for expanded queries, not normally visible */
  
  public FieldsQuery(SrndQuery q, List<String> fieldNames, char fieldOp) {
    this.q = q;
    this.fieldNames = fieldNames;
    this.fieldOp = fieldOp;
  }
  
  public FieldsQuery(SrndQuery q, String fieldName, char fieldOp) {
    this.q = q;
    fieldNames = new ArrayList<String>();
    fieldNames.add(fieldName);
    this.fieldOp = fieldOp;
  }
  
  @Override
  public boolean isFieldsSubQueryAcceptable() {
    return false;
  }
  
  public Query makeLuceneQueryNoBoost(BasicQueryFactory qf) {
    if (fieldNames.size() == 1) { /* single field name: no new queries needed */
      return q.makeLuceneQueryFieldNoBoost(fieldNames.get(0), qf);
    } else { /* OR query over the fields */
      List<SrndQuery> queries = new ArrayList();
      Iterator<String> fni = getFieldNames().listIterator();
      SrndQuery qc;
      while (fni.hasNext()) {
        qc = (SrndQuery) q.clone();
        queries.add( new FieldsQuery( qc, fni.next(), fieldOp));
      }
      OrQuery oq = new OrQuery(queries,
                              true /* infix OR for field names */,
                              OrOperatorName);
      System.out.println(getClass().toString() + ", fields expanded: " + oq.toString()); /* needs testing */
      return oq.makeLuceneQueryField(null, qf);
    }
  }

  @Override
  public Query makeLuceneQueryFieldNoBoost(String fieldName, BasicQueryFactory qf) {
    return makeLuceneQueryNoBoost(qf); /* use this.fieldNames instead of fieldName */
  }

  
  public List<String> getFieldNames() {return fieldNames;}

  public char getFieldOperator() { return fieldOp;}
  
  @Override
  public String toString() {
    StringBuilder r = new StringBuilder();
    r.append("(");
    fieldNamesToString(r);
    r.append(q.toString());
    r.append(")");
    return r.toString();
  }
  
  protected void fieldNamesToString(StringBuilder r) {
    Iterator<String> fni = getFieldNames().listIterator();
    while (fni.hasNext()) {
      r.append(fni.next());
      r.append(getFieldOperator());
    }
  }
}