《Lucene in Action》第二版中对MoreLikeThis 介绍的例子，搜索类似的书籍，代码如下，供大家学习参考：
public class BooksMoreLikeThis {
public static void main(String[] args) throws Throwable {
String indexDir = System.getProperty("index.dir");
FSDirectory directory = FSDirectory.open(new File(indexDir));
IndexReader reader = IndexReader.open(directory);
IndexSearcher searcher = new IndexSearcher(reader);
int numDocs = reader.maxDoc();
MoreLikeThis mlt = new MoreLikeThis(reader);
mlt.setFieldNames(new String[] {"title", "author"});
mlt.setMinTermFreq(1); //默认值是2，建议自己做限制，否则可能查不出结果
mlt.setMinDocFreq(1); //默认值是5，建议自己做限制，否则可能查不出结果
for (int docID = 0; docID < numDocs; docID++) {
System.out.println();
Document doc = reader.document(docID);
System.out.println(doc.get("title"));
Query query = mlt.like(docID);
System.out.println(" query=" + query);
TopDocs similarDocs = searcher.search(query, 10);
if (similarDocs.totalHits == 0)
System.out.println(" None like this");
for(int i=0;i<similarDocs.scoreDocs.length;i++) {
if (similarDocs.scoreDocs[i].doc != docID) {
doc = reader.document(similarDocs.scoreDocs[i].doc);
System.out.println(" -> " + doc.getField("title").stringValue());
}
}
}
searcher.close();
reader.close();
directory.close();
}
}