lucene 中关于Store.YES 关于Store.NO的解释

总算搞明白 lucene 中关于Store.YES 关于Store.NO的解释了

一直对Lucene Store.YES不太理解，网上多数的说法是存储字段，NO为不存储。

这样的解释有点郁闷：字面意思一看就明白，但是不解。

之前我的理解是：如果字段可以不存储，那要怎么搜索这个不存储的字段呢？

原来Lucene就是这样，可以设置某些字段为不存储，但是可以用来检索。

终于在一篇文章里看到这几句话，突然间就明白了。

//Store.YES 保存可以查询可以打印内容
Field storeYes = new Field("storeyes","storeyes",Store.YES,Index.TOKENIZED);
//Store.NO 不保存可以查询不可打印内容由于不保存内容所以节省空间，但是这个索引是存在的，可以通过这个索引去检索
Field storeNo = new Field("storeno","storeno",Store.NO,Index.TOKENIZED);
//Store.COMPRESS 压缩保存可以查询可以打印内容可以节省生成索引文件的空间，Field storeCompress = new Field("storecompress","storecompress",Store.COMPRESS,Index.TOKENIZED);

至此，对于理解Store.YES，Store.NO 就是不存储就不能直接获取此字段的内容，存储了就可以。但是两者都可以用于检索。

字段是否能被搜索，还与Index有关。

package luxun.lucene.base;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.Field.Index;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.FieldDoc;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.SortField.Type;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.LockObtainFailedException;
import org.apache.lucene.store.SimpleFSDirectory;
import org.apache.lucene.util.Version;
public class SortFieldValueTest {

   @SuppressWarnings("deprecation")
   public void buildIndex() throws CorruptIndexException, LockObtainFailedException, IOException {
       File indexDir = new File("/home/cristo/luxun_test/luxunlucenetest/04/index");
       // dataDir is the directory that hosts the text files that to be indexed
       Directory directory = new SimpleFSDirectory(indexDir);
       Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_47);
       IndexWriter writer = new IndexWriter(directory,    new IndexWriterConfig(Version.LUCENE_47, analyzer));
       Document doc = new Document();
       doc.add(new Field("id", "1", Store.YES, Index.NO));
       doc.add(new Field("text", "lucene", Store.NO, Index.ANALYZED));
       doc.add(new Field("time", "2010", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       doc.add(new Field("tide", "149", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       writer.addDocument(doc);
       doc = new Document();
       doc.add(new Field("id", "3", Store.YES, Index.NO));
       doc.add(new Field("text", "lucene", Store.NO, Index.ANALYZED));
       doc.add(new Field("time", "2011", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       doc.add(new Field("tide", "14", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       writer.addDocument(doc);
       doc = new Document();
       doc.add(new Field("id", "2", Store.YES, Index.NO));
       doc.add(new Field("text", "lucene", Store.NO, Index.ANALYZED));
       doc.add(new Field("time", "2001", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       doc.add(new Field("tide", "13", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       writer.addDocument(doc);
       doc = new Document();
       doc.add(new Field("id", "5", Store.YES, Index.NO));
       doc.add(new Field("text", "lucene", Store.NO, Index.ANALYZED));
       doc.add(new Field("time", "2001", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       doc.add(new Field("tide", "19", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       writer.addDocument(doc);
       doc = new Document();
       doc.add(new Field("id", "9", Store.YES, Index.NO));
       doc.add(new Field("text", "lucene", Store.NO, Index.ANALYZED));
       doc.add(new Field("time", "2171", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       doc.add(new Field("tide", "19", Store.NO, Index.NOT_ANALYZED_NO_NORMS));
       writer.addDocument(doc);
       writer.commit();
       writer.close();
   }
   public void searchWithOneSortField() throws CorruptIndexException, IOException {//可以通过对time属性进行索引，排序，获取对应的id
       File indexDir = new File("/home/cristo/luxun_test/luxunlucenetest/04/index");
       @SuppressWarnings("deprecation")
       IndexSearcher searcher = new IndexSearcher(IndexReader.open(FSDirectory.open( indexDir)));
       TermQuery termQuery = new TermQuery(new Term("time", "2001"));
       TopFieldDocs topFieldDocs = searcher.search(termQuery, null, 10, new Sort(new SortField("time",Type.STRING, true)));
       ScoreDoc[] sorDocs = topFieldDocs.scoreDocs;
       for (ScoreDoc doc : sorDocs) {
       //   FieldDoc fieldDoc = (FieldDoc) doc;
           System.out.println(searcher.doc(doc.doc).get("id"));
       }
   }

   public static void main(String[] args) throws CorruptIndexException, IOException {
       SortFieldValueTest SortFieldValueTest1=new SortFieldValueTest();
       SortFieldValueTest1.buildIndex();
       SortFieldValueTest1.searchWithOneSortField();

   }
}

参考http://blog.csdn.net/telnetor/article/details/6187378

http://www.codeweblog.com/%E6%80%BB%E7%AE%97%E6%89%BE%E5%88%B0lucene-%E5%85%B3%E4%BA%8Estore-yes%E7%9A%84%E8%A7%A3%E9%87%8A%E4%BA%86/