Apache Lucene API

X-Git-Url: https://git.mdrn.pl/pylucene.git/blobdiff_plain/a2e61f0c04805cfcb8706176758d1283c7e3a55c..aaeed5504b982cf3545252ab528713250aa33eed:/lucene-java-3.5.0/lucene/src/java/overview.html?ds=inline diff --git a/lucene-java-3.5.0/lucene/src/java/overview.html b/lucene-java-3.5.0/lucene/src/java/overview.html new file mode 100644 index 0000000..83ae570 --- /dev/null +++ b/lucene-java-3.5.0/lucene/src/java/overview.html @@ -0,0 +1,193 @@ + + + + + Apache Lucene API + + + +

Apache Lucene is a high-performance, full-featured text search engine library. +Here's a simple example how to use Lucene for indexing and searching (using JUnit +to check if the results are what we expect):

+ + + + + + +

+    Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
+
+    // Store the index in memory:
+    Directory directory = new RAMDirectory();
+    // To store an index on disk, use this instead:
+    //Directory directory = FSDirectory.open("/tmp/testindex");
+    IndexWriter iwriter = new IndexWriter(directory, analyzer, true,
+                                          new IndexWriter.MaxFieldLength(25000));
+    Document doc = new Document();
+    String text = "This is the text to be indexed.";
+    doc.add(new Field("fieldname", text, Field.Store.YES,
+        Field.Index.ANALYZED));
+    iwriter.addDocument(doc);
+    iwriter.close();
+    
+    // Now search the index:
+    IndexReader ireader = IndexReader.open(directory); // read-only=true
+    IndexSearcher isearcher = new IndexSearcher(ireader);
+    // Parse a simple query that searches for "text":
+    QueryParser parser = new QueryParser("fieldname", analyzer);
+    Query query = parser.parse("text");
+    ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
+    assertEquals(1, hits.length);
+    // Iterate through the results:
+    for (int i = 0; i < hits.length; i++) {
+      Document hitDoc = isearcher.doc(hits[i].doc);
+      assertEquals("This is the text to be indexed.", hitDoc.get("fieldname"));
+    }
+    isearcher.close();
+    ireader.close();
+    directory.close();

+ + + + + +

The Lucene API is divided into several packages:

+ +

+org.apache.lucene.analysis +defines an abstract Analyzer +API for converting text from a java.io.Reader +into a TokenStream, +an enumeration of token Attributes. +A TokenStream can be composed by applying TokenFilters +to the output of a Tokenizer. +Tokenizers and TokenFilters are strung together and applied with an Analyzer. +A handful of Analyzer implementations are provided, including StopAnalyzer +and the grammar-based StandardAnalyzer.
+org.apache.lucene.document +provides a simple Document +class. A Document is simply a set of named Fields, +whose values may be strings or instances of java.io.Reader.
+org.apache.lucene.index +provides two primary classes: IndexWriter, +which creates and adds documents to indices; and IndexReader, +which accesses the data in the index.
+org.apache.lucene.search +provides data structures to represent queries (ie TermQuery +for individual words, PhraseQuery +for phrases, and BooleanQuery +for boolean combinations of queries) and the abstract Searcher +which turns queries into TopDocs. +IndexSearcher +implements search over a single IndexReader.
+org.apache.lucene.queryParser +uses JavaCC to implement a +QueryParser.
+org.apache.lucene.store +defines an abstract class for storing persistent data, the Directory, +which is a collection of named files written by an IndexOutput +and read by an IndexInput. +Multiple implementations are provided, including FSDirectory, +which uses a file system directory to store files, and RAMDirectory +which implements files as memory-resident data structures.
+org.apache.lucene.util +contains a few handy data structures and util classes, ie BitVector +and PriorityQueue.

+To use Lucene, an application should: +

+Create Documents by +adding +Fields;
+Create an IndexWriter +and add documents to it with addDocument();
+Call QueryParser.parse() +to build a query from a string; and
+Create an IndexSearcher +and pass the query to its search() +method.

+Some simple examples of code which does this are: +

+ IndexFiles.java creates an +index for all the files contained in a directory.
+ SearchFiles.java prompts for +queries and searches an index.

+To demonstrate these, try something like: +

> java -cp lucene.jar:lucene-demo.jar:lucene-analyzers-common.jar org.apache.lucene.demo.IndexFiles rec.food.recipes/soups +
adding rec.food.recipes/soups/abalone-chowder +
[ ... ] + +
> java -cp lucene.jar:lucene-demo.jar:lucene-analyzers-common.jar org.apache.lucene.demo.SearchFiles +
Query: chowder +
Searching for: chowder +
34 total matching documents +
1. rec.food.recipes/soups/spam-chowder +
[ ... thirty-four documents contain the word "chowder" ... ] + +
Query: "clam chowder" AND Manhattan +
Searching for: +"clam chowder" +manhattan +
2 total matching documents +
1. rec.food.recipes/soups/clam-chowder +
[ ... two documents contain the phrase "clam chowder" +and the word "manhattan" ... ] +
[ Note: "+" and "-" are canonical, but "AND", "OR" +and "NOT" may be used. ]

+ + +