Search engines Learning (Five) Lucene indexing operation

One, code analysis

/ ** 
 * Getting Lucene 
 * Operating index 
 * / 
public  class ManageIndex { 

    public IndexWriter getIndexWriter () throws Exception {
         // set index database location 
        Directory Directory = FSDirectory.open ( new new File ( "E: \\ \\ zhanghaoBF luceneSolr \ \ indexLibrary " ) .toPath ()); 
        Analyzer Analyzer = new new StandardAnalyzer (); // create word object (the official recommended standard tokenizer) 
        indexWriterConfig indexWriterConfig = new new indexWriterConfig (Analyzer); // word set using 
        return  new new IndexWriter (directory, indexWriterConfig);// index object 
    } 

    / ** 
     * Full delete ( PS: index inside the document will be deleted) 
     * 
     * @throws Exception
      * / 
    @Test 
    public  void deleteAllIndex () throws Exception { 
        IndexWriter IndexWriter = getIndexWriter (); // Gets stream object index 
        indexWriter.deleteAll (); // delete all index 
        indexWriter.close (); // off flow 
    } 

    / ** 
     * conditional deletion ( PS: index inside the document will be deleted) 
     * 
     * @throws Exception
      * /
    @Test 
    public  void deleteIndex () throws Exception { 
        the IndexWriter IndexWriter = getIndexWriter (); // get a stream object index 
        Query Query = new new TermQuery ( new new Term ( "fileContent", "Lucene")); // the PS: TermQuery is accurate matching 
        indexWriter.deleteDocuments (Query); // conditional delete an index 
        indexWriter.close (); // off flow 
    } 

    / ** 
     * Review ( the PS: after removing the first added, and the same inside the database is not modified, a distinction) 
     * 
     * @throws Exception
      * / 
    @Test 
    public void updateIndex () throws Exception {
         // Get index stream object 
        the IndexWriter IndexWriter = getIndexWriter (); 

        // build a document object 
        the Document DOC = new new the Document (); 
        doc.add ( new new the TextField ( "fileName", "new file name " , Field.Store.YES)); 
        doc.add ( new new TextField (" fileContent "," new file content " , Field.Store.YES)); 

        // call update, delete the first qualifying index off (including the term and document exists index library), and then just added the document object is added to the index database 
        indexWriter.updateDocument ( new new Term ( "fileName", "is"), doc);// conditionally remove the index, then add the new index
         // PS:Deleted document will still occupy the corresponding document ID, the new document at the last (and when the database ID from the growing delete add one more reason) 

        // off flow 
        indexWriter.close (); 
    } 
}

Second, note

1, delete the time, the corresponding index at the library ID Term and documents will be deleted .

2, modify the operation is actually first qualifying term and documentation will be deleted , and then add the new document.

3, delete the document, the document ID will not be released, or occupied.

4, the flow must remember to run off.