lucene自定义过滤器

package util;

import java.io.IOException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.util.OpenBitSet;
/**
 * 过滤指定的文件名
 * @author user
 *
 */
public class MyIDFilter extends Filter{
	
	public static void main(String[] args) throws Exception {
		IndexSearcher searcher = DocUtil.getSearcher();
		Query query = new TermQuery(new Term("content","java"));
		Filter filterFilename = new MyIDFilter();
//		TopDocs topdoc = searcher.search(query, 100);
		TopDocs topdoc = searcher.search(query, filterFilename, 100);
		DocUtil.printDocument(topdoc, searcher);
		searcher.close();
	}
	
	private String[] filenames = {"1.txt","2.txt","3.txt"};
	@Override
	public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
		//创建一个元素bitset,默认所有的元素都是0
		OpenBitSet obs = new OpenBitSet(reader.maxDoc());
		//先把元素填满,只要有传入的文档号被设置,该文档的对应元素就会被设置为1
		obs.set(0, reader.maxDoc() - 1);
		int[] docs = new int[1];//存储查询出来的对象的位置
		int[] freqs = new int[1];//存储查询出来的对象出现的频率
		//根据id所在的doc位置,并且将其设置为0
		for(String filename : filenames){
			//获取TermDocs
			TermDocs tds = reader.termDocs(new Term("filename",filename));
			//会将查询出来的对象的位置存储到docs中,出现的频率存储到freqs中,返回获取的条数
			int count = tds.read(docs, freqs);
			if(count == 1){
				//将这个元素删除
				obs.clear(docs[0]);
			}
		}
		return obs;
	}
}