15.7. Interoperating with Java Lucene
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## 15.7. Interoperating with Java Lucene

### 15.7.1. File Formats

Zend_Search_Lucene index file formats are binary compatible with a Lucene version 1.4 and above.

A detailed description of this format is available here: http://lucene.apache.org/java/docs/fileformats.html.

### 15.7.2. Index Directory

After index creation, the index directory will contain several files:

- `segments` file is a list of index segments.

- `*.cfs` files contain index segments. Note! Optimized index has always only one segment.

- `deletable` file is a list of files that are no longer used by the index, but which could not be deleted.

### 15.7.3. Java Source Code

The Java program listing below provides an example of how to index a file using Java Lucene:

    /**
    * Index creation:
    */
    import org.apache.lucene.index.IndexWriter;
    import org.apache.lucene.document.*;

    import java.io.*

    ...

    IndexWriter indexWriter = new IndexWriter("/data/my_index",
                                              new SimpleAnalyzer(), true);

    ...

    String filename = "/path/to/file-to-index.txt"
    File f = new File(filename);

    Document doc = new Document();
    doc.add(Field.Text("path", filename));
    doc.add(Field.Keyword("modified",DateField.timeToString(f.lastModified())));
    doc.add(Field.Text("author", "unknown"));
    FileInputStream is = new FileInputStream(f);
    Reader reader = new BufferedReader(new InputStreamReader(is));
    doc.add(Field.Text("contents", reader));

    indexWriter.addDocument(doc);

### 15.7.4. Using LuceneIndexCreation.jar

To get started with Zend_Search_Lucene quickly, a JAR file (Java) has been created to generate an index from the command line. For more information on JAR files, please visit: http://java.sun.com/docs/books/tutorial/jar/basics/index.html.

LuceneIndexCreation.jar consumes text files and builds an index from them. Usage:

        java -jar LuceneIndexCreation.jar [-c] [-s] <document_dir> <index_dir>
        -c   - force index to be case sensitive
        -s   - store content in the index

This command consumes the directory `<document_dir>`, including all of its subdirectories, and produces a Lucene index. The index is a set of files that will be stored in a separate directory that is specified by `<index_dir>`.

For each document to be indexed, LuceneIndexCreation creates a document object with three fields: a contents field containing the contents (body) of the document, a modified field containing the file modification time, and the full path and filename in a path field.

If `-c` is specified, then index is forced to be case sensitive. Otherwise all terms are converted to lower case before to be added into the index.

If `-s` is specified, then document's content is also stored in the index and can be retrieved with `path` and `modified` fields.

Otherwise only `path` and `modified` fields are stored, and `contents` field is only indexed. In this case document content must be retrieved from an original source by its path.

Please be careful, using `-s` option increases index size near five times.

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