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Lucene example source code file (TermsFilter.java)

This example Lucene source code file (TermsFilter.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

docidset, filter, io, ioexception, iterator, iterator, override, override, set, term, term, termdocs, termsfilter, termsfilter, treeset, util

The Lucene TermsFilter.java source code

package org.apache.lucene.search;

/**
 * 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.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.util.OpenBitSet;

/**
 * Constructs a filter for docs matching any of the terms added to this class. 
 * Unlike a RangeFilter this can be used for filtering on multiple terms that are not necessarily in 
 * a sequence. An example might be a collection of primary keys from a database query result or perhaps 
 * a choice of "category" labels picked by the end user. As a filter, this is much faster than the 
 * equivalent query (a BooleanQuery with many "should" TermQueries)
 *
 */
public class TermsFilter extends Filter
{
	Set<Term> terms=new TreeSet();
	
	/**
	 * Adds a term to the list of acceptable terms   
	 * @param term
	 */
	public void addTerm(Term term)
	{
		terms.add(term);
	}
	
/* (non-Javadoc)
   * @see org.apache.lucene.search.Filter#getDocIdSet(org.apache.lucene.index.IndexReader)
	 */
  @Override
  public DocIdSet getDocIdSet(IndexReader reader) throws IOException
	{
    OpenBitSet result=new OpenBitSet(reader.maxDoc());
        TermDocs td = reader.termDocs();
        try
        {
            for (Iterator<Term> iter = terms.iterator(); iter.hasNext();)
            {
                Term term = iter.next();
                td.seek(term);
                while (td.next())
                {
                    result.set(td.doc());
                }
            }
        }
        finally
        {
            td.close();
        }
        return result;
	}
	
	@Override
	public boolean equals(Object obj)
	{
		if(this == obj)
			return true;
		if((obj == null) || (obj.getClass() != this.getClass()))
				return false;
		TermsFilter test = (TermsFilter)obj;
		return (terms == test.terms ||
					 (terms != null && terms.equals(test.terms)));
	}

	@Override
	public int hashCode()
	{
		int hash=9;
		for (Iterator<Term> iter = terms.iterator(); iter.hasNext();)
		{
			Term term = iter.next();
			hash = 31 * hash + term.hashCode();			
		}
		return hash;
	}
	
}

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