2002-01-26 11:38:28 -05:00
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2004-03-04 09:41:28 -05:00
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Copyright 1999-2004 The Apache Software Foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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2002-01-26 11:38:28 -05:00
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<!-- start the processing -->
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<!-- ====================================================================== -->
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<!-- GENERATED FILE, DO NOT EDIT, EDIT THE XML FILE IN xdocs INSTEAD! -->
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<!-- Main Page Section -->
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<!-- ====================================================================== -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>
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<meta name="author" value="Andrew C. Oliver">
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<meta name="email" value="acoliver@apache.org">
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2002-02-11 14:45:24 -05:00
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2003-01-04 11:29:08 -05:00
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2005-02-14 11:48:47 -05:00
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<title>Apache Lucene - Apache Lucene - Basic Demo Sources Walkthrough</title>
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</head>
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<body bgcolor="#ffffff" text="#000000" link="#525D76">
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<table border="0" width="100%" cellspacing="0">
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<!-- TOP IMAGE -->
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<tr>
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<td align="left">
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2005-05-02 14:50:45 -04:00
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<a href="http://www.apache.org"><img src="http://lucene.apache.org/java/docs/images/asf-logo.gif" width="387" height="100" border="0"/></a>
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</td>
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<td align="right">
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<a href="http://lucene.apache.org/"><img src="./images/lucene_green_300.gif" alt="Apache Lucene" border="0"/></a>
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</td>
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</tr>
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</table>
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<table border="0" width="100%" cellspacing="4">
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<tr><td colspan="2">
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<hr noshade="" size="1"/>
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</td></tr>
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<tr>
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<!-- LEFT SIDE NAVIGATION -->
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<td width="20%" valign="top" nowrap="true">
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2003-10-09 10:40:30 -04:00
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<!-- ============================================================ -->
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<p><strong>About</strong></p>
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<ul>
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<li> <a href="./index.html">Overview</a>
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</li>
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<li> <a href="./features.html">Features</a>
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</li>
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<li> <a href="http://wiki.apache.org/jakarta-lucene/PoweredBy">Powered by Lucene</a>
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</li>
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<li> <a href="./whoweare.html">Who We Are</a>
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</li>
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2005-03-26 07:58:35 -05:00
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<li> <a href="./mailinglists.html">Mailing Lists</a>
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2002-01-26 11:38:28 -05:00
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</li>
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</ul>
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<p><strong>Resources</strong></p>
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<ul>
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2004-02-28 21:43:36 -05:00
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<li> <a href="http://wiki.apache.org/jakarta-lucene">Wiki</a>
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</li>
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2004-12-30 16:50:43 -05:00
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<li> <a href="http://wiki.apache.org/jakarta-lucene/LuceneFAQ">FAQ</a>
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2002-06-20 10:23:48 -04:00
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</li>
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<li> <a href="./gettingstarted.html">Getting Started</a>
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2002-05-16 01:16:10 -04:00
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</li>
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<li> <a href="./queryparsersyntax.html">Query Syntax</a>
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2002-10-29 23:14:11 -05:00
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</li>
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<li> <a href="./fileformats.html">File Formats</a>
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</li>
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<li> <a href="./api/index.html">Javadoc</a>
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</li>
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<li> <a href="./contributions.html">Contributions</a>
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2002-12-04 00:56:33 -05:00
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</li>
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<li> <a href="./benchmarks.html">Benchmarks</a>
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</li>
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2005-09-21 06:41:16 -04:00
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<li> <a href="http://issues.apache.org/jira/browse/LUCENE">Issue Tracker</a>
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2002-12-04 00:56:33 -05:00
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</li>
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<li> <a href="./lucene-sandbox/">Lucene Sandbox</a>
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</li>
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</ul>
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<p><strong>Download</strong></p>
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<ul>
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<li> <a href="http://www.apache.org/dyn/closer.cgi/jakarta/lucene/binaries/">Binaries</a>
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</li>
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<li> <a href="http://www.apache.org/dyn/closer.cgi/jakarta/lucene/source/">Source Code</a>
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</li>
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<li> <a href="http://svn.apache.org/viewcvs.cgi/lucene/">Source Repository</a>
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</li>
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</ul>
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</td>
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<td width="80%" align="left" valign="top">
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<table border="0" cellspacing="0" cellpadding="2" width="100%">
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<tr><td bgcolor="#525D76">
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<font color="#ffffff" face="arial,helvetica,sanserif">
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<a name="About the Code"><strong>About the Code</strong></a>
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</font>
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</td></tr>
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<tr><td>
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<blockquote>
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<p>
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In this section we walk through the sources behind the basic Lucene demo such as where to
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find it, its parts and their function. This section is intended for Java developers
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wishing to understand how to use Apache Lucene in their applications.
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</p>
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</blockquote>
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</p>
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</td></tr>
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<tr><td><br/></td></tr>
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</table>
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<table border="0" cellspacing="0" cellpadding="2" width="100%">
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<tr><td bgcolor="#525D76">
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<font color="#ffffff" face="arial,helvetica,sanserif">
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<a name="Location of the source"><strong>Location of the source</strong></a>
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</font>
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</td></tr>
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<tr><td>
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<blockquote>
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<p>
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Relative to the directory created when you extracted Lucene or retreived it from Subversion, you
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should see a directory called "src" which in turn contains a directory called "demo".
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This is the root for all of the Lucene demos. Under this directory is org/apache/lucene/demo,
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this is where all the Java sources live.
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</p>
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<p>
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Within this directory you should see the IndexFiles class we executed earlier. Bring that
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up in vi or your alternative text editor and lets take a look at it.
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</p>
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</blockquote>
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</p>
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</td></tr>
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<tr><td><br/></td></tr>
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</table>
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<table border="0" cellspacing="0" cellpadding="2" width="100%">
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<tr><td bgcolor="#525D76">
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<font color="#ffffff" face="arial,helvetica,sanserif">
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<a name="IndexFiles"><strong>IndexFiles</strong></a>
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</font>
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</td></tr>
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<tr><td>
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<blockquote>
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<p>
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As we discussed in the previous walkthrough, the IndexFiles class creates a Lucene Index.
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Lets take a look at how it does this.
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</p>
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<p>
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The first substantial thing the main function does is instantiate an instance
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of IndexWriter. It passes a string called "index" and a new instance of a class called
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"StandardAnalyzer". The "index" string is the name of the directory that all index information
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should be stored in. Because we're not passing any path information, one must assume this
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will be created as a subdirectory of the current directory (if it does not already exist). On
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some platforms this may actually result in it being created in other directories (such as
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the user's home directory).
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</p>
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<p>
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The <b>IndexWriter</b> is the main class responsible for creating indicies. To use it you
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must instantiate it with a path that it can write the index into, if this path does not
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exist it will create it, otherwise it will refresh the index living at that path. You
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2005-04-22 00:31:17 -04:00
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must a also pass an instance of <b>org.apache.lucene.analysis.Analyzer</b>.
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</p>
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<p>
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The <b>Analyzer</b>, in this case, the <b>StandardAnalyzer</b> is little more than a standard Java
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Tokenizer, converting all strings to lowercase and filtering out useless words and characters from the index.
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By useless words and characters I mean common language words such as articles (a, an, the, etc.) and other
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strings that would be useless for searching (e.g. <b>'s</b>) . It should be noted that there are different
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rules for every language, and you should use the proper analyzer for each. Lucene currently
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provides Analyzers for English and German, more can be found in the Lucene Sandbox.
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</p>
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<p>
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Looking down further in the file, you should see the indexDocs() code. This recursive function
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simply crawls the directories and uses FileDocument to create Document objects. The Document
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is simply a data object to represent the content in the file as well as its creation time and
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location. These instances are added to the indexWriter. Take a look inside FileDocument. It's
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not particularly complicated, it just adds fields to the Document.
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</p>
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<p>
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As you can see there isn't much to creating an index. The devil is in the details. You may also
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wish to examine the other samples in this directory, particularly the IndexHTML class. It is
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a bit more complex but builds upon this example.
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</p>
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</blockquote>
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</p>
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</td></tr>
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<tr><td><br/></td></tr>
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</table>
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<table border="0" cellspacing="0" cellpadding="2" width="100%">
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<tr><td bgcolor="#525D76">
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<font color="#ffffff" face="arial,helvetica,sanserif">
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<a name="Searching Files"><strong>Searching Files</strong></a>
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</font>
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</td></tr>
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<tr><td>
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<blockquote>
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<p>
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The SearchFiles class is quite simple. It primarily collaborates with an IndexSearcher, StandardAnalyzer
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(which is used in the IndexFiles class as well) and a QueryParser. The query parser is constructed
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with an analyzer used to interperate your query in the same way the Index was interperated: finding
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the end of words and removing useless words like 'a', 'an' and 'the'. The Query object contains the
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results from the QueryParser which is passed to the searcher. The searcher results are returned in
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a collection of Documents called "Hits" which is then iterated through and displayed to the user.
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</p>
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</blockquote>
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</p>
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</td></tr>
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<tr><td><br/></td></tr>
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</table>
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<table border="0" cellspacing="0" cellpadding="2" width="100%">
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<tr><td bgcolor="#525D76">
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<font color="#ffffff" face="arial,helvetica,sanserif">
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<a name="The Web example..."><strong>The Web example...</strong></a>
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</font>
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</td></tr>
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<blockquote>
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<p>
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<a href="demo3.html">read on>>></a>
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</p>
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</blockquote>
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</p>
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</td></tr>
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<tr><td><br/></td></tr>
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</table>
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</td>
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</tr>
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<!-- FOOTER -->
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<tr><td colspan="2">
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<hr noshade="" size="1"/>
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<tr><td colspan="2">
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<div align="center"><font color="#525D76" size="-1"><em>
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Copyright © 1999-2005, The Apache Software Foundation
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</em></font></div>
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</table>
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</body>
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</html>
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<!-- end the processing -->
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2002-02-11 14:45:24 -05:00
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