The Apache Lucene Project has released the version 2.1 of Apache Lucene (JAVA). This release has many improvements since release 2.0, including new features, performance improvements, bug fixes, etc. 详细信息请看： CHANGES.txt
Apache Lucene 2.1 includes index format changes that are not readable by older versions of Lucene. Lucene 2.1 can both read and update older Lucene indexes. Adding to an index with an older format will cause it to be converted to the newer format.
Binary and source distributions are available here.
