1.Deploy：
1）Download：http://lucene.apache.org/
2）
You need four JARs: the Lucene JAR, the queryparser JAR, the common analysis JAR, and the Lucene demo JAR. You should see the Lucene JAR file in thecore/ directory you created when you extracted the archive -- it should be named something like lucene-core-{version}.jar. You should also see files called lucene-queryparser-{version}.jar, lucene-analyzers-common-{version}.jar and lucene-demo-{version}.jar underqueryparser, analysis/common/ and demo/, respectively.
Put all four of these files in your JavaCLASSPATH.
2. Indexing Files
1）java org.apache.lucene.demo.IndexFiles -docs {path-to-lucene}/src
2）java org.apache.lucene.demo.SearchFiles
3. Location of the source
- IndexFiles.java: code to create a Lucene index.
- SearchFiles.java: code to search a Lucene index.
3.1 IndexFiles
As we discussed in the previous walk-through, the IndexFiles class creates a Lucene Index. Let's take a look at how it does this.
The main() method parses the command-line parameters, then in preparation for instantiating IndexWriter,
opens a Directory,
and instantiates StandardAnalyzer and IndexWriterConfig.
The value of the -index command-line parameter is the name of the filesystem directory where all index information should be stored. If IndexFiles is invoked with a relative path given in the -index command-line parameter, or if the -indexcommand-line parameter is not given, causing the default relative index path "index" to be used, the index path will be created as a subdirectory of the current working directory (if it does not already exist). On some platforms, the index path may be created in a different directory (such as the user's home directory).
The -docs command-line parameter value is the location of the directory containing files to be indexed.
The -update command-line parameter tells IndexFiles not to delete the index if it already exists. When -update is not given, IndexFiles will first wipe the slate clean before indexing any documents.
Lucene Directorys
are used by the IndexWriter to store information in the index. In addition to the FSDirectory implementation
we are using, there are several other Directory subclasses that can write to RAM, to databases, etc.
Lucene Analyzers
are processing pipelines that break up text into indexed tokens, a.k.a. terms, and optionally perform other operations on these tokens, e.g. downcasing, synonym insertion, filtering out unwanted tokens, etc. The Analyzer we are
using is StandardAnalyzer, which creates tokens using the Word Break rules from the Unicode Text Segmentation algorithm specified in Unicode
Standard Annex #29; converts tokens to lowercase; and then filters out stopwords. Stopwords are common language words such as articles (a, an, the, etc.) and other tokens that may have less value for searching. It should be noted that there are different
rules for every language, and you should use the proper analyzer for each. Lucene currently provides Analyzers for a number of different languages (see the javadocs under lucene/analysis/common/src/java/org/apache/lucene/analysis).
The IndexWriterConfig instance holds all configuration for IndexWriter. For example, we set the OpenMode to use here based on the value of the -update command-line parameter.
Looking further down in the file, after IndexWriter is instantiated, you should see the indexDocs() code. This recursive function crawls the directories and creates Document objects.
The Document is simply a data object to represent the text content from the file as well as its creation time and location. These instances are added to the IndexWriter. If the -update command-line
parameter is given, the IndexWriterConfig OpenMode will be set to OpenMode.CREATE_OR_APPEND,
and rather than adding documents to the index, the IndexWriter will update them in the index by attempting to find an already-indexed document with the same identifier (in our case, the file path serves as the
identifier); deleting it from the index if it exists; and then adding the new document to the index.
3.2 Searching Files
The SearchFiles class is quite simple. It primarily collaborates with
an IndexSearcher, StandardAnalyzer,
(which is used in the IndexFiles class as well) and a QueryParser.
The query parser is constructed with an analyzer used to interpret your query text in the same way the documents are interpreted: finding word boundaries, downcasing, and removing useless words like 'a', 'an' and 'the'. The Query object
contains the results from the QueryParser which
is passed to the searcher. Note that it's also possible to programmatically construct a rich Query object
without using the query parser. The query parser just enables decoding the Lucene
query syntax into the corresponding Query object.
SearchFiles uses the IndexSearcher.search(query,n) method
that returns TopDocs with
max n hits. The results are printed in pages, sorted by score (i.e. relevance).