John Smart provides a quick intro to Lucene, a powerful and elegant library for full-text indexing and searching in Java, with which you can add rich full-text search functionality to your Java web application.
A Tutorial Introduction to Full-Text Indexing in Java
About The Author
Eugenia Loli
Ex-programmer, ex-editor in chief at OSNews.com, now a visual artist/filmmaker.
Follow me on Twitter @EugeniaLoli
Lucene is one of the high quality libraries i have used. it is focused, well designed and blazingly fast. there is a complete search engine mechanism also exist based on Lucene, Nutc. i suggest taking a look.
http://lucene.apache.org/nutch/
Lucene also has a very active, friendly community. Programmers wanting to explore Lucene will enjoy the mailing lists where many core Lucene gurus are extremely active. Beginners are welcome and the experts are patient and helpful.