Lucene增加高亮显示后结果更高明显了,但是返回结果的速度比较慢.原因是Lucene做每一篇文档的相关关键词的高亮显示时,在运行时执行了很多遍的分词操作,降低了性能.
TermVector保存Token.getPositionIncrement() 和Token.startOffset() 以及Token.endOffset() 信息。利用Lucene中新增加的Token信息的保存结果以后,就不需要为了高亮显示而在运行时解析每篇文档。通过Field方法控制是否保存该信息
public void searcher() throws IOException{
IndexReader reader = IndexReader.open(directory);
IndexSearcher searcher = new IndexSearcher(directory);
TermQuery query = new TermQuery(new Term("subject","java"));
Hits hits = searcher.search(query);
//高亮显示设置
SimpleHTMLFormatter simpleHTMLFormatter = new SimpleHTMLFormatter("<font color='red'>","</font>");
Highlighter highlighter =new Highlighter(simpleHTMLFormatter,new QueryScorer(query));
// 这个100是指定关键字字符串的context的长度,你可以自己设定,因为不可能返回整篇正文内容
highlighter.setTextFragmenter(new SimpleFragmenter(100));
for(int i = 0; i < hits.length(); i++){
Document doc = hits.doc(i);
TermPositionVector termFreqVector = (TermPositionVector)reader.getTermFreqVector(hits.id(i), "subject");
TokenStream tokenStream = TokenSources.getTokenStream(termFreqVector);
String result = highlighter.getBestFragment(tokenStream, doc.get("subject"));
System.out.println(doc.get("title"));
System.out.println(result);
}
}
搜索结果:
java
<font color='red'>java</font>一门编程语言