2002-01-26 11:38:28 -05:00
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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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2002-01-26 11:38:28 -05:00
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<title>Jakarta Lucene - Jakarta 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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<a href="http://jakarta.apache.org"><img src="http://jakarta.apache.org/images/jakarta-logo.gif" border="0"/></a>
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</td>
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<td align="right">
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<a href="http://jakarta.apache.org/lucene/"><img src="./images/lucene_green_300.gif" alt="Jakarta 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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<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="./powered.html">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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<li> <a href="http://jakarta.apache.org/site/mail.html">Mailing Lists</a>
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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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<li> <a href="http://www.lucene.com/cgi-bin/faq/faqmanager.cgi">FAQ (Official)</a>
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</li>
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<li> <a href="./gettingstarted.html">Getting Started</a>
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</li>
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<li> <a href="http://www.jguru.com/faq/Lucene">JGuru FAQ</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/bugs.html">Bugs</a>
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</li>
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<li> <a href="http://nagoya.apache.org/bugzilla/buglist.cgi?bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&email1=&emailtype1=substring&emailassigned_to1=1&email2=&emailtype2=substring&emailreporter2=1&bugidtype=include&bug_id=&changedin=&votes=&chfieldfrom=&chfieldto=Now&chfieldvalue=&product=Lucene&short_desc=&short_desc_type=allwordssubstr&long_desc=&long_desc_type=allwordssubstr&bug_file_loc=&bug_file_loc_type=allwordssubstr&keywords=&keywords_type=anywords&field0-0-0=noop&type0-0-0=noop&value0-0-0=&cmdtype=doit&order=%27Importance%27">Lucene Bugs</a>
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</li>
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<li> <a href="./resources.html">Articles</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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2002-02-23 17:03:21 -05:00
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</li>
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</ul>
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<p><strong>Plans</strong></p>
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<ul>
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<li> <a href="./luceneplan.html">Application Extensions</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>Download</strong></p>
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<ul>
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<li> <a href="http://jakarta.apache.org/site/binindex.html">Binaries</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/sourceindex.html">Source Code</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/cvsindex.html">CVS Repositories</a>
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</li>
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</ul>
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<p><strong>Jakarta</strong></p>
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<ul>
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<li> <a href="http://jakarta.apache.org/site/getinvolved.html">Get Involved</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/acknowledgements.html">Acknowledgements</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/contact.html">Contact</a>
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</li>
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<li> <a href="http://jakarta.apache.org/site/legal.html">Legal</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 Jakarta 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 CVS, 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 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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must a also pass an instance of <b>org.apache.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>Stop Analyzer</b> is little more than a standard Java
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Tokenizer, converting all strings to lowercase and filtering out useless words from the index.
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By useless words I mean common language words such as articles (a,an,the) and other words that
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would be useless for searching. It should be noted that there are different rules for every
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language, and you should use the proper analyzer for each. Lucene currently provides Analyzers
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for English and German.
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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. Its
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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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<tr><td>
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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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</td></tr>
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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 © 1999-2002, Apache Software Foundation
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</em></font></div>
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</td></tr>
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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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