Lucene Tutorial(1) - How to index Lucene

I'm first in use of lucene. I think this blog is not perfect for you because I'm not professional.

but what I wrote is by reading and stuying the book of Lucene in action 2.

so I hope this blog is going to be useful some of you

1. Indexing (3.6.1 version)

why Use?

when i can use this lucene?

Suppose~!  you have many text-files in your local computer, window xp, 7 and so on  search programs allow you find filename but not content in textfiles. 

how do search content?

so you have to use search engine like lucene

how to Index ?

explain :  

indexDir = directory that you want to index   (a.txt, b.txt, c.txt)

dataDir = destination directory where indexing file will store

IndexWriter = it is like translator original file into indexed file

TextFilesFilter class = filtering file extension

Document  = it is like file info class

Running this code

your first experience is done.

public class Indexer {

public static void main(String[] args) throws Exception {

if (args.length != 2) {

throw new IllegalArgumentException("Usage: java " + Indexer.class.getName() + " <index dir> <data dir>");

}

final String indexDir = args[0];

final String dataDir = args[1];

final long start = System.currentTimeMillis();

final Indexer indexer = new Indexer(indexDir);

int numIndexed;

try {

numIndexed = indexer.index(dataDir, new TextFilesFilter());

} finally {

indexer.close();

}

final long end = System.currentTimeMillis();

System.out.println("Indexing " + numIndexed + " files took " + (end - start) + " milliseconds");

}

private IndexWriter writer;

public Indexer(

String indexDir) throws IOException {

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

writer = new IndexWriter(dir, new StandardAnalyzer(Version.LUCENE_30), true, IndexWriter.MaxFieldLength.UNLIMITED);

}

public void close() throws IOException {

writer.close();

}

public int index(String dataDir, FileFilter filter) throws Exception {

final File[] files = new File(dataDir).listFiles();

for (final File f : files) {

if (!f.isDirectory() && !f.isHidden() && f.exists() && f.canRead() && (filter == null || filter.accept(f))) {

indexFile(f);

}

}

return writer.numDocs();

}

private static class TextFilesFilter implements FileFilter {

@Override

public boolean accept(File path) {

return path.getName().toLowerCase().endsWith(".txt");

}

}

protected Document getDocument(File f) throws Exception {

final Document doc = new Document();

doc.add(new Field("content", new FileReader(f)));

doc.add(new Field("filename", f.getName(), Field.Store.YES, Field.Index.NOT_ANALYZED));

doc.add(new Field("fullpath", f.getCanonicalPath(), Field.Store.YES, Field.Index.NOT_ANALYZED));

doc.add(new NumericField("filesize").setIntValue((int) f.length()));

System.out.println(f.length());

return doc;

}

private void indexFile(File f) throws Exception {

System.out.println("Indexing " + f.getCanonicalPath());

System.out.println(f.lastModified());

final Document doc = getDocument(f);

writer.addDocument(doc);

}

}