Lucene is a sub-project of the Apache Software Foundation 4 jakarta project team. It is an open source full-text search engine toolkit, but it is not a complete full-text search engine, but a The architecture of the full-text search engine provides a complete query engine and index engine, and some text analysis engines (in two Western languages, English and German).

The purpose of Lucene is to provide software developers with a simple and easy-to-use toolkit to easily implement the full-text search function in the target system, or to build a complete full-text search engine based on it. Lucene provides a simple but powerful application programming interface that can perform full-text indexing and search. Lucene is a mature free and open source tool in the Java development environment. On its own, Lucene is currently and in recent years the most popular free Java information retrieval library. Information retrieval libraries are often mentioned, and although they are related to search engines, they should not be confused with search engines.
The use of Lucene is based on a huge index library. Generally speaking, when we search, we do not search directly in the database, but directly from the index library, because the index library is binary format, so the retrieval speed is very fast. Therefore, when we use Lucene to search, we must first create or obtain an index library.