Apache Lucene
http://lucene.apache.org/
http://lucene.apache.org/java/docs/index.html
http://lucene.apache.org/java/docs/api/index.html
http://www.lucenetutorial.com/your-first-project.html
http://www.lucenetutorial.com/techniques/indexing-databases.html
한글 관련
https://github.com/need4spd/walkingword/tree/master/src/com/tistory/devyongsik/sample
http://setong.tistory.com/43