lucene中的IndexWriter.setMaxFieldLength()

lucene中的IndexWriter.setMaxFieldLength()

老版本的Lucene中，IndexWriter的maxFieldLength是指一个索引中的最大的Field个数。

这个属性在Lucene2.9.0中是不可见的，对其的修改被放在相应的setMaxFieldLength(Int l)和getMaxFiedLength()中；

当索引中的Field的个数等于这个属性时，新增的任何field都会被忽略，即使对己经存在相同的Field新增内容也是不可以的。附上一个测试类（Lucene in action）

package test;

import java.io.File;

import java.io.IOException;

import junit.framework.TestCase;

import org.apache.lucene.analysis.SimpleAnalyzer;

import org.apache.lucene.document.Document;

import org.apache.lucene.document.Field;

import org.apache.lucene.index.IndexWriter;

import org.apache.lucene.index.Term;

import org.apache.lucene.search.IndexSearcher;

import org.apache.lucene.search.Query;

import org.apache.lucene.search.ScoreDoc;

import org.apache.lucene.search.TermQuery;

import org.apache.lucene.search.TopScoreDocCollector;

import org.apache.lucene.store.Directory;

import org.apache.lucene.store.FSDirectory;

public class FieldLengthTest extends TestCase {

private Directory dir;

private String[] keywords = {"1", "2"};

private String[] unindexed = {"Netherlands", "Italy"};

private String[] unstored = {"Amsterdam has lots of bridges",

"Venice has lots of canals"};

private String[] text = {"Amsterdam", "Venice"};

protected void setUp() throws IOException {

String indexDir =

System.getProperty("java.io.tmpdir", "tmp") +

System.getProperty("file.separator") + "index-dir";

dir = FSDirectory.open(new File(indexDir));

}

public void testFieldSize() throws IOException {

addDocuments(dir, 10);

assertEquals(1, getHitCount("contents", "bridges"));

addDocuments(dir, 1);

assertEquals(0, getHitCount("contents", "bridges"));

}

private int getHitCount(String fieldName, String searchString)

throws IOException {

IndexSearcher searcher = new IndexSearcher(dir, true);

Term t = new Term(fieldName, searchString);

Query query = new TermQuery(t);

TopScoreDocCollector tsdc = TopScoreDocCollector.create(10, false);

searcher.search(query, tsdc);

ScoreDoc[] hits = tsdc.topDocs().scoreDocs;

int hitCount = hits.length;

searcher.close();

return hitCount;

}

private void addDocuments(Directory dir, int maxFieldLength)

throws IOException {

IndexWriter writer = new IndexWriter(dir, new SimpleAnalyzer(),

true, IndexWriter.MaxFieldLength.LIMITED);

writer.setMaxFieldLength(maxFieldLength);

for (int i = 0; i < keywords.length; i++) {

Document doc = new Document();

doc.add(new Field("contents", unstored[i], Field.Store.YES, Field.Index.ANALYZED));

//doc.add(new Field("contents", unstored[i], Field.Store.NO, Field.Index.ANALYZED));

doc.add(new Field("country", unindexed[i], Field.Store.YES, Field.Index.NO));

doc.add(new Field("contents", unstored[i], Field.Store.NO, Field.Index.ANALYZED));

doc.add(new Field("city", text[i], Field.Store.YES, Field.Index.ANALYZED));

writer.addDocument(doc);

}

writer.optimize();

writer.close();

}

}

（转自：http://blog.sina.com.cn/s/blog_49b531af0100it66.html）