lucene updateDocument not work - lucene

Question

I am using Lucene 3.6. I want to know why update does not work. Is there anything wrong?
public class TokenTest
{
private static String IndexPath = "D:\\update\\index";
private static Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_33);
public static void main(String[] args) throws Exception
{
try
{
update();
display("content", "content");
}
catch (IOException e)
{
e.printStackTrace();
}
}
#SuppressWarnings("deprecation")
public static void display(String keyField, String words) throws Exception
{
IndexSearcher searcher = new IndexSearcher(FSDirectory.open(new File(IndexPath)));
Term term = new Term(keyField, words);
Query query = new TermQuery(term);
TopDocs results = searcher.search(query, 100);
ScoreDoc[] hits = results.scoreDocs;
for (ScoreDoc hit : hits)
{
Document doc = searcher.doc(hit.doc);
System.out.println("doc_id = " + hit.doc);
System.out.println("内容: " + doc.get("content"));
System.out.println("路径:" + doc.get("path"));
}
}
public static String update() throws Exception
{
IndexWriterConfig writeConfig = new IndexWriterConfig(Version.LUCENE_33, analyzer);
IndexWriter writer = new IndexWriter(FSDirectory.open(new File(IndexPath)), writeConfig);
Document document = new Document();
Field field_name2 = new Field("path", "update_path", Field.Store.YES, Field.Index.ANALYZED);
Field field_content2 = new Field("content", "content update", Field.Store.YES, Field.Index.ANALYZED);
document.add(field_name2);
document.add(field_content2);
Term term = new Term("path", "qqqqq");
writer.updateDocument(term, document);
writer.optimize();
writer.close();
return "update_path";
}
}

Answer 1

I assume you want to update your document such that field "path" = "qqqq". You have this exactly backwards (please read the documentation).
updateDocument performs two steps:
Find and delete any documents containing term
In this case, none are found, because your indexed documents does not contain path:qqqq
Add the new document to the index.
You appear to be doing the opposite, trying to lookup by document, then add the term to it, and it doesn't work that way. What you are looking for, I believe, is something like:
Term term = new Term("content", "update");
document.removeField("path");
document.add("path", "qqqq");
writer.updateDocument(term, document);