Package org.apache.lucene.document

The logical representation of a Document for indexing and searching.

See: Description

Package org.apache.lucene.document Description

The logical representation of a Document for indexing and searching.

The document package provides the user level logical representation of content to be indexed and searched. The package also provides utilities for working with Documents and Fieldables.

Document and Fieldable

A Document is a collection of Fieldables. A Fieldable is a logical representation of a user's content that needs to be indexed or stored. Fieldables have a number of properties that tell Lucene how to treat the content (like indexed, tokenized, stored, etc.) See the Field implementation of Fieldable for specifics on these properties.

Note: it is common to refer to Documents having Fields, even though technically they have Fieldables.

Working with Documents

First and foremost, a Document is something created by the user application. It is your job to create Documents based on the content of the files you are working with in your application (Word, txt, PDF, Excel or any other format.) How this is done is completely up to you. That being said, there are many tools available in other projects that can make the process of taking a file and converting it into a Lucene Document. To see an example of this, take a look at the Lucene demo and the associated source code for extracting content from HTML.

The DateTools is a utility class to make dates and times searchable (remember, Lucene only searches text). NumericField is a special helper class to simplify indexing of numeric values (and also dates) for fast range range queries with NumericRangeQuery (using a special sortable string representation of numeric values).

The FieldSelector class provides a mechanism to tell Lucene how to load Documents from storage. If no FieldSelector is used, all Fieldables on a Document will be loaded. As an example of the FieldSelector usage, consider the common use case of displaying search results on a web page and then having users click through to see the full document. In this scenario, it is often the case that there are many small fields and one or two large fields (containing the contents of the original file). Before the FieldSelector, the full Document had to be loaded, including the large fields, in order to display the results. Now, using the FieldSelector, one can FieldSelectorResult.LAZY_LOAD the large fields, thus only loading the large fields when a user clicks on the actual link to view the original content.