A variable-length format for positive integers is defined where the high-order bit of each byte indicates whether more bytes remain to be read. The low-order seven bits are appended as increasingly more significant bits in the resulting integer value. Thus values from zero to 127 may be stored in a single byte, values from 128 to 16,383 may be stored in two bytes, and so on.

可变格式的整型定义：最高位表示是否˜q˜æœ‰å­—节要读取，低七位就是就是具体的有效位，æ·ÕdŠ åˆ?/p>

¾l“果数据中。比å¦?0000001 最高位表示0åQŒé‚£ä¹ˆè¯´æ˜Žè¿™ä¸ªæ•°ž®±æ˜¯ä¸€ä¸ªå­—节表½Cºï¼Œæœ‰æ•ˆä½æ˜¯åŽé¢çš„七ä½?000001åQŒå€égØ“1ã€?0000010 00000001 ½W¬ä¸€ä¸ªå­—节最高位ä¸?åQŒè¡¨½CºåŽé¢è¿˜æœ‰å­—节，½W¬äºŒä½æœ€é«˜ä½0表示到此为止了，卛_°±æ˜¯ä¸¤ä¸ªå­—节，那么具体的值注意，是从最后一个字节的七位有效数放在最前面åQŒä¾‹Æ¡æ”¾¾|®ï¼Œæœ€åŽæ˜¯½W¬ä¸€ä¸ªè‡ªå·Þqš„七位有效位，所以这个数表示 0000001 0000010åQŒæ¢½Ž—成整数ž®±æ˜¯130

VInt Encoding Example

Lucene源代码中˜q›è¡Œå­˜å‚¨å’Œè¯»å–是˜q™æ ·çš„。OutputStream是负责写åQ?/p>

tomcatå’Œjdk都安装好åQ?/p>

二：nutch-0.9.tar.gz
        ž®†ä¸‹è½½åˆ°çš„tar.gz包，解压åˆ?opt目录下åƈ改名åQ?br />         #gunzip -xf nutch-0.9.tar.gz |tar xf
        #mv nutch-0.9.tar.gz /usr/local/nutch
      
       ‹¹‹è¯•çŽ¯å¢ƒæ˜¯å¦è®„¡½®æˆåŠŸåQšè¿è¡Œï¼š/urs/local/nutch/bin/nutch看一下有没有命ä×o参数输出åQŒå¦‚果有说明没问题ã€?/p>

       抓取˜q‡ç¨‹åQ?cd /opt/nutch
                         #mkdir urls
                         #vi nutch.txt 输入www.aicent.net
                         #vi conf/crawl-urlfilter.txt 加入以下信息åQšåˆ©ç”¨æ­£åˆ™è¡¨è¾‘Ö¼å¯¹ç½‘ç«™url抓取½{›é€‰ã€?br />                         /**** accept hosts in MY.DOMAIN.NAME******/
                                +^http://([a-z0-9]*\.)*aicent.net/
                       #vi nutch/nutch-site.xmlåQˆç»™è‡ªå·±çš„蜘蛛取一个名字）讄¡½®å¦‚下åQ?br />    <configuration>
<property>
    <name>http.agent.name</name>
    <value>test/unique</value>
</property>
</configuration>

                开始抓取：#bin/nutch crawl urls -dir crawl -detpth 5 -thread 10 >& crawl.log

½{‰å¾…一会，旉™—´ä¾æ®¾|‘站的大ž®ï¼Œå’Œè®¾¾|®çš„抓取深度ã€?/p>

三：apache-tomcat

                在这里，当你看到每次‹‚€ç´¢çš„™åµé¢ä¸?里，需要修改一下参敎ͼŒå› äØ“tomcat中的nutch的检索èµ\径不寚w€ æˆçš„ã€?br />                 #vi /usr/local/tomcat/webapps/ROOT/WEB-INF/classes/nutch-site.xml
<property>
<name>searcher.dir</name>
<value>/opt/nutch/crawl</value>抓取¾|‘页所在的路径
<description>My path to nutch's searcher dir.</description>
</property>

                #/opt/tomcat/bin/startup.sh

OK,搞定。。�/p>

问题汇总：

˜qè¡ŒåQšsh ./bin/nutch crawl urls -dir crawl -depth 3 -threads 60 -topN 100 >&./logs/nutch_log.log

1.Exception in thread "main" java.io.IOException: Job failed!
        at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:604)
        at org.apache.nutch.crawl.Injector.inject(Injector.java:162)
        at org.apache.nutch.crawl.Crawl.main(Crawl.java:115)
¾|‘上查有说是JDK版本的问题，不能用JDK1.6åQŒäºŽæ˜¯å®‰è£?.5。但是还是同æ ïLš„问题åQŒå¥‡æ€ªå•Šã€?br /> 于是¾l§ç®‹googleåQŒå‘现有如下的可能：

Injector: Converting injected urls to crawl db entries.
Exception in thread "main" java.io.IOException: Job failed!
        at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:604)
        at org.apache.nutch.crawl.Injector.inject(Injector.java:162)
        at org.apache.nutch.crawl.Crawl.main(Crawl.java:115)

说明åQšä¸€èˆ¬äØ“crawl-urlfilters.txt中配¾|®é—®é¢˜ï¼Œæ¯”如˜q‡æ×o条äšg应äØ“
+^http://www.ihooyo.com ,而配¾|®æˆäº?http://www.ihooyo.com ˜q™æ ·çš„情况就引è“v如上错误ã€?/p>

但是自己的配¾|®æ ¹æœ¬å°±æ²¡æœ‰é—®é¢˜å•Šã€?br /> 在Logs目录下面除了生成nutch_log.log˜q˜è‡ªåŠ¨ç”Ÿæˆä¸€ä¸ªlogæ–‡äšgåQšhadoop.log
发现有错误出玎ͼš

2009-07-22 22:20:55,501 INFO  crawl.Crawl - crawl started in: crawl
2009-07-22 22:20:55,501 INFO  crawl.Crawl - rootUrlDir = urls
2009-07-22 22:20:55,502 INFO  crawl.Crawl - threads = 60
2009-07-22 22:20:55,502 INFO  crawl.Crawl - depth = 3
2009-07-22 22:20:55,502 INFO  crawl.Crawl - topN = 100
2009-07-22 22:20:55,603 INFO  crawl.Injector - Injector: starting
2009-07-22 22:20:55,604 INFO  crawl.Injector - Injector: crawlDb: crawl/crawldb
2009-07-22 22:20:55,604 INFO  crawl.Injector - Injector: urlDir: urls
2009-07-22 22:20:55,605 INFO  crawl.Injector - Injector: Converting injected urls to crawl db entries.
2009-07-22 22:20:56,574 INFO  plugin.PluginRepository - Plugins: looking in: /opt/nutch/plugins
2009-07-22 22:20:56,720 INFO  plugin.PluginRepository - Plugin Auto-activation mode: [true]
2009-07-22 22:20:56,720 INFO  plugin.PluginRepository - Registered Plugins:
2009-07-22 22:20:56,720 INFO  plugin.PluginRepository -         the nutch core extension points (nutch-extensionpoints)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Basic Query Filter (query-basic)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Basic URL Normalizer (urlnormalizer-basic)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Basic Indexing Filter (index-basic)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Html Parse Plug-in (parse-html)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Basic Summarizer Plug-in (summary-basic)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Site Query Filter (query-site)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         HTTP Framework (lib-http)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Text Parse Plug-in (parse-text)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Regex URL Filter (urlfilter-regex)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Pass-through URL Normalizer (urlnormalizer-pass)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Http Protocol Plug-in (protocol-http)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Regex URL Normalizer (urlnormalizer-regex)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         OPIC Scoring Plug-in (scoring-opic)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         CyberNeko HTML Parser (lib-nekohtml)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         JavaScript Parser (parse-js)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         URL Query Filter (query-url)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Regex URL Filter Framework (lib-regex-filter)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository - Registered Extension-Points:
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Nutch Summarizer (org.apache.nutch.searcher.Summarizer)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Nutch URL Normalizer (org.apache.nutch.net.URLNormalizer)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Nutch Protocol (org.apache.nutch.protocol.Protocol)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Nutch Analysis (org.apache.nutch.analysis.NutchAnalyzer)
2009-07-22 22:20:56,721 INFO  plugin.PluginRepository -         Nutch URL Filter (org.apache.nutch.net.URLFilter)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Nutch Indexing Filter (org.apache.nutch.indexer.IndexingFilter)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Nutch Online Search Results Clustering Plugin (org.apache.nutch.clustering.OnlineClusterer)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         HTML Parse Filter (org.apache.nutch.parse.HtmlParseFilter)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Nutch Content Parser (org.apache.nutch.parse.Parser)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Nutch Scoring (org.apache.nutch.scoring.ScoringFilter)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Nutch Query Filter (org.apache.nutch.searcher.QueryFilter)
2009-07-22 22:20:56,722 INFO  plugin.PluginRepository -         Ontology Model Loader (org.apache.nutch.ontology.Ontology)
2009-07-22 22:20:56,786 WARN  regex.RegexURLNormalizer - can't find rules for scope 'inject', using default
2009-07-22 22:20:56,829 WARN  mapred.LocalJobRunner - job_2319eh
java.lang.RuntimeException: java.net.UnknownHostException: jackliu: jackliu
        at org.apache.hadoop.io.SequenceFile$Writer.<init>(SequenceFile.java:617)
        at org.apache.hadoop.io.SequenceFile$Writer.<init>(SequenceFile.java:591)
        at org.apache.hadoop.io.SequenceFile.createWriter(SequenceFile.java:364)
        at org.apache.hadoop.io.SequenceFile.createWriter(SequenceFile.java:390)
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.startPartition(MapTask.java:294)
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpillToDisk(MapTask.java:355)
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$100(MapTask.java:231)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:180)
        at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:126)
Caused by: java.net.UnknownHostException: jackliu: jackliu
        at java.net.InetAddress.getLocalHost(InetAddress.java:1353)
        at org.apache.hadoop.io.SequenceFile$Writer.<init>(SequenceFile.java:614)
        ... 8 more

也就是Host配置错误åQŒäºŽæ˜¯ï¼š
Add the following to your /etc/hosts file
127.0.0.1    jackliu

˜q™æ¬¡å†æ¬¡˜qè¡ŒåQŒç»“果成功！

2:http://127.0.0.1:8080/nutch-0.9
 è¾“å…¥nutch˜q›è¡ŒæŸ¥è¯¢åQŒç»“果报错：
 HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: /search.jsp(151,22) Attribute value  language + "/include/header.html" is quoted with " which must be escaped when used within the value
 org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
 org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
 org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:198)
 org.apache.jasper.compiler.Parser.parseQuoted(Parser.java:299)
 org.apache.jasper.compiler.Parser.parseAttributeValue(Parser.java:249)
 org.apache.jasper.compiler.Parser.parseAttribute(Parser.java:211)
 org.apache.jasper.compiler.Parser.parseAttributes(Parser.java:154)
 org.apache.jasper.compiler.Parser.parseInclude(Parser.java:867)
 org.apache.jasper.compiler.Parser.parseStandardAction(Parser.java:1134)
 org.apache.jasper.compiler.Parser.parseElements(Parser.java:1461)
 org.apache.jasper.compiler.Parser.parse(Parser.java:137)
 org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255)
 org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
 org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:170)
 org.apache.jasper.compiler.Compiler.compile(Compiler.java:332)
 org.apache.jasper.compiler.Compiler.compile(Compiler.java:312)
 org.apache.jasper.compiler.Compiler.compile(Compiler.java:299)
 org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:586)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.

分析åQšæŸ¥çœ‹nutch Web应用根目录下的search.jsp可知åQŒæ˜¯å¼•å·åŒšw…çš„问题ã€?/p>

<jsp:include page="<%= language + "/include/header.html"%>"/>  //line 152 search.jsp

½W¬ä¸€ä¸ªå¼•å·å’ŒåŽé¢½W¬ä¸€ä¸ªå‡ºçŽ°çš„引号˜q›è¡ŒåŒšw…åQŒè€Œä¸æ˜¯å’Œ˜q™ä¸€è¡Œæœ€åŽä¸€ä¸ªå¼•å¯‚¿›è¡ŒåŒ¹é…ï¼Œæ‰€ä»¥é—®é¢˜å°±å‡ºçŽ°äº†ã€?/p>

解决æ–ÒŽ³•åQ?/p>

ž®†è¯¥è¡Œä»£ç ä¿®æ”¹äØ“åQ?lt;jsp:include page="<%= language+urlsuffix %>"/>

˜q™é‡Œæˆ‘们定一个字½W¦ä¸²urlsuffixåQŒæˆ‘们把它定义在language字符串定义之后，

  String language =   // line 116 search.jsp
    ResourceBundle.getBundle("org.nutch.jsp.search", request.getLocale())
    .getLocale().getLanguage();
 String urlsuffix="/include/header.html";

修改完成后，为确保修æ”ÒŽˆåŠŸï¼Œé‡å¯ä¸€ä¸‹Tomcat服务器，˜q›è¡Œæœçƒ¦åQŒä¸å†æŠ¥é”™ã€?/p>

3.无法查询¾l“æžœåQ?br />   å¯ÒŽ¯”nutch_log.log的结果发现和¾|‘上描述的不同，而且crawl里面只有两个文äšg夹segmentså’ŒcrawldbåQŒåŽæ¥é‡æ–°çˆ¬äº†ä¸€‹Æ?br />   发现˜q™æ¬¡æ˜¯å¥½çš„，奇怪不知道ä¸ÞZ»€ä¹ˆä¸Š‹Æ¡çˆ¬çš„失败了ã€?br />  
4.cached.jsp explain.jsp½{‰éƒ½æœ‰ä¸Šé?的错误，更正˜q‡åŽ»ž®±OK了ã€?/p>

5.今天èŠ×ƒº†ä¸€ä¸Šåˆå’ŒåŠä¸ªä¸‹åˆçš„æ—‰™—´¾lˆäºŽæžå®šäº†nutch的安装和配置了。明天ç‘ô¾l­å­¦ä¹ ã€?/p>

™åºåºå¾ˆé‡è¦ï¼š
    String[] phrase = new String[] {"fox", "quick"};
assertFalse("hop flop", matched(phrase, 2));
assertTrue("hop hop slop", matched(phrase, 3));

原理如下图所½Cºï¼š


对于查询关键字quickå’ŒfoxåQŒåªéœ€è¦fox¿UÕdŠ¨ä¸€ä¸ªä½¾|®å³å¯åŒ¹é…quick brown fox。而对于foxå’Œquick˜q™ä¸¤ä¸ªå…³é”®å­—
需要将fox¿UÕdŠ¨ä¸‰ä¸ªä½ç½®ã€‚移动的距离­‘Šå¤§åQŒé‚£ä¹ˆè¿™™å¹è®°å½•çš„scorež®Þp¶Šž®ï¼Œè¢«æŸ¥è¯¢å‡ºæ¥çš„可能行就­‘Šå°äº†ã€?br />
SpanQuery利用位置信息查询更有意思的查询åQ?br />
SpanQuery type         Description
SpanTermQuery         Used in conjunction with the other span query types. On its own, it’s
                                        functionally equivalent to TermQuery.
SpanFirstQuery         Matches spans that occur within the first part of a field.
SpanNearQuery         Matches spans that occur near one another.
SpanNotQuery         Matches spans that don’t overlap one another.
SpanOrQuery             Aggregates matches of span queries.

SpanFirstQueryåQšTo query for spans that occur within the first n positions of a field, use Span-FirstQuery.



quick = new SpanTermQuery(new Term("f", "quick"));
brown = new SpanTermQuery(new Term("f", "brown"));
red = new SpanTermQuery(new Term("f", "red"));
fox = new SpanTermQuery(new Term("f", "fox"));
lazy = new SpanTermQuery(new Term("f", "lazy"));
sleepy = new SpanTermQuery(new Term("f", "sleepy"));
dog = new SpanTermQuery(new Term("f", "dog"));
cat = new SpanTermQuery(new Term("f", "cat"));

SpanFirstQuery sfq = new SpanFirstQuery(brown, 2);
assertNoMatches(sfq);
sfq = new SpanFirstQuery(brown, 3);
assertOnlyBrownFox(sfq);

SpanNearQueryåQ?br />
彼此盔R‚»çš„è·¨åº?

      首先åQŒå¼ºè°ƒä¸€ä¸‹PhraseQuery对象åQŒè¿™ä¸ªå¯¹è±¡ä¸å±žäºŽè·¨åº¦æŸ¥è¯¢¾c»ï¼Œä½†èƒ½å®Œæˆè·¨åº¦æŸ¥è¯¢åŠŸèƒ½ã€?/p>

      匚w…åˆ°çš„文档所包含的项通常是彼此相é‚ȝš„åQŒè€ƒè™‘到原文档中在查询™å¹ä¹‹é—´å¯èƒ½æœ‰ä¸€äº›ä¸­é—´é¡¹åQŒæˆ–ä¸ÞZº†èƒ½æŸ¥è¯¢å€’排的项åQŒPhraseQuery讄¡½®äº†slop因子åQ?font color="#ff0000">但是˜q™ä¸ªslop因子æŒ?个项允许最大间隔距¼›»ï¼Œä¸æ˜¯ä¼ ç»Ÿæ„ä¹‰ä¸Šçš„距离åQŒæ˜¯æŒ‰é¡ºåºç»„成给定的短语åQŒæ‰€éœ€è¦ç§»åŠ¨ä½¾|®çš„‹Æ¡æ•°åQ?font color="#0000ff">˜q™è¡¨½CºPhraseQuery是必™åÀLŒ‰ç…§é¡¹åœ¨æ–‡æ¡£ä¸­å‡ºçŽ°çš„顺序计½Ž—跨度的åQŒå¦‚quick brown fox为文档，则quick fox2个项的slopä¸?åQŒquick向后¿UÕdŠ¨ä¸€‹Æ?而fox quick需要quick向后¿UÕdŠ¨3‹Æ¡ï¼Œæ‰€ä»¥slopä¸?

      其次åQŒæ¥çœ‹ä¸€ä¸‹SpanQuery的子¾c»SpanTermQueryã€?/p>

      它能跨度查询åQ?font color="#0000ff">òq¶ä¸”不一定非要按™å¹åœ¨æ–‡æ¡£ä¸­å‡ºçŽ°çš„™åºåºåQŒå¯ä»¥ç”¨ä¸€ä¸ªç‹¬ç«‹çš„标记表示查询对象必须按顺序，或允许按倒过来的™åºåºå®ŒæˆåŒšw…ã€?font color="#ff0000">匚w…çš„跨度也不是指移动位¾|®çš„‹Æ¡æ•°åQŒæ˜¯æŒ‡ä»Ž½W¬ä¸€ä¸ªè·¨åº¦çš„起始位置到最后一个跨度的¾l“束位置ã€?/font>

      在SpanNearQuery中将SpanTermQuery对象作äØ“SpanQuery对象使用的效果，与ä‹É用PharseQuery的效果非常相伹{€‚在SpanNearQuery的构造函æ•îC¸­çš„第三个参数为inOrder标志åQŒè®¾¾|®è¿™ä¸ªæ ‡å¿—，表示按项在文档中出现的顺序倒过来的™åºåºã€?/p>

      å¦?the quick brown fox jumps over the lazy dog˜q™ä¸ªæ–‡æ¡£

      public void testSpanNearQuery() throws Exception{

           SpanQuery[] quick_brown_dog=new SpanQuery[]{quick,brown,dog};

           SpanNearQuery snq=new SpanNearQuery(quick_brown_dog,0,true);//按正帔R¡ºåº?跨度ä¸?,对三个项˜q›è¡ŒæŸ¥è¯¢

           assertNoMatches(snq);//无法匚w…

           SpanNearQuery snq=new SpanNearQuery(quick_brown_dog,4,true);//按正帔R¡ºåº?跨度ä¸?,对三个项˜q›è¡ŒæŸ¥è¯¢

           assertNoMatches(snq);//无法匚w…

           SpanNearQuery snq=new SpanNearQuery(quick_brown_dog,4,true);//按正帔R¡ºåº?跨度ä¸?,对三个项˜q›è¡ŒæŸ¥è¯¢

           assertOnlyBrownFox(snq);//匚w…æˆåŠŸ    

           SpanNearQuery snq=new SpanNearQuery(new SpanQuery[]{lazy,fox},3,false);//按相反顺åº?跨度ä¸?,对三个项˜q›è¡ŒæŸ¥è¯¢

           assertOnlyBrownFox(snq);//匚w…æˆåŠŸ   

           //下面使用PhraseQuery˜q›è¡ŒæŸ¥è¯¢åQŒå› ä¸ºæ˜¯æŒ‰é¡ºåºï¼Œæ‰€ä»¥lazyå’Œfox必须要跨度äØ“5

           PhraseQuery pq=new PhraseQuery();

           pq.add(new Term("f","lazy"));

           pq.add(new Term("f","lazy"));

           pq.setslop(4);

           assertNoMatches(pq);//跨度4无法匚w…

           //PharseQuery,slop因子ä¸?

           pq.setSlop(5);

           assertOnlyBrownFox(pq);          

      }


3.PhrasePrefixQuery 主要用来˜q›è¡ŒåŒä¹‰è¯æŸ¥è¯¢çš„åQ?br />     IndexWriter writer = new IndexWriter(directory, new WhitespaceAnalyzer(), true);
    Document doc1 = new Document();
    doc1.add(Field.Text("field", "the quick brown fox jumped over the lazy dog"));
    writer.addDocument(doc1);
    Document doc2 = new Document();
    doc2.add(Field.Text("field","the fast fox hopped over the hound"));
    writer.addDocument(doc2);

    PhrasePrefixQuery query = new PhrasePrefixQuery();
    query.add(new Term[] {new Term("field", "quick"), new Term("field", "fast")});
    query.add(new Term("field", "fox"));

    Hits hits = searcher.search(query);
    assertEquals("fast fox match", 1, hits.length());
    query.setSlop(1);
    hits = searcher.search(query);
    assertEquals("both match", 2, hits.length());

int *binarySearch(int val, int array[], int n)

{

int m = n/2;

if(n <= 0) return NULL;

if(val == array[m]) return array + m;

if(val < array[m]) return binarySearch(val, array, m);

else return binarySearch(val, array+m+1, n-m-1);

}

对于有n个元素的数组来说åQŒäºŒå…ƒæœç´¢ç®—法进行最å¤?+log2(n)‹Æ¡æ¯”较ã€?如果有一百万元素åQŒå¤§æ¦‚比è¾?0‹Æ¡ï¼Œä¹Ÿå°±æ˜¯æœ€å¤?0‹Æ¡é€’归执行binarySearch()函数ã€?/p>

3.Index dates
 Document doc = new Document();
 doc.add(Field.Keyword("indexDate", new Date()));

4.Tuning indexing performance
 IndexWriter          System property                            Default value          Description
 --------------------------------------------------------------------------------------------------
 mergeFactor          org.apache.lucene.mergeFactor        10       Controls segment merge  frequency and size
 maxMergeDocs     org.apache.lucene.maxMergeDocs   Integar.MAX_VALUE    Limits the number of  documents per segement
 minMergeDocs         org.apache.lucene.minMergeDocs     10     Controls the amount of   RAM used when indexing

mergeFactor控制写入¼‹¬ç›˜å‰å†…存中¾~“存的document数量åQŒåŒæ—¶æŽ§åˆ¶merge index segments的频率。其默认值是10åQŒå³å­˜æ»¡10ä¸?br /> documents后就必须写入¼‹¬ç›˜åQŒè€Œä¸”如果segment的数量达åˆ?0çš„çñ”数的时候会merge成一个segmentåQŒå½“然maxMergeDocs限制了每ä¸?br /> segment最大能够保存的document数量。mergeFactor­‘Šå¤§çš„话ž®Þp¶Šèƒ½åˆ©ç”¨RAMåQŒæé«˜index的效率，但是mergeFactor­‘Šé«˜ä¹Ÿå°±æ„å‘³ç€
merge的频率就­‘Šä½ŽåQŒä¼šå¯èƒ½å¯ÆD‡´segments的数量很大（因äؓ没有mergeåQ‰ï¼Œ˜q™æ ·search的时候就需要打开更多的segmentæ–‡äšgåQŒä¹Ÿž®?br /> 降低了search的效率。minMergeDocs is another IndexWriter instance variable that affects indexing performance. Its
value controls how many Documents have to be buffered before they’re merged to a segment.也即是说minMergeDocs也具æœ?br /> mergeFactor控制¾~“å­˜document数量的功能ã€?/p>

5.RAMDirectory帮助利用RAMåQŒä¹Ÿå¯ä»¥é‡‡ç”¨é›†ç¾¤æˆ–者多¾U¿ç¨‹çš„方式充分利用硬件和软äšg资源åQŒæé«˜index的效率ã€?/p>

6.有时候对于每个field可能希望控制其大ž®ï¼Œæ¯”如只对å‰?000个term做indexåQŒè¿™ä¸ªæ—¶å€™å°±éœ€è¦ä‹É用maxFieldLength来控制ã€?/p>

7.IndexWriter’s optimize()æ–ÒŽ³•ž®±æ˜¯ž®†segments˜q›è¡ŒmergeåQŒé™ä½Žsegments的数量从而减ž®‘search的时候读取index的时间ã€?/p>

8.注意多线½E‹çŽ¯å¢ƒä¸‹çš„工作：an index-modifying IndexReader operation can’t be executed
while an index-modifying IndexWriter operation is in progress.ä¸ÞZº†é˜²æ­¢è¯¯ç”¨åQŒLucene在ä‹É用某些API时会¾l?br /> index上锁ã€?/p>

1.TermQuery常用åQŒå¯¹ä¸€ä¸ªTermåQˆæœ€ž®çš„索引块，包含一个field名字和å€û|¼‰˜q›è¡Œç´¢å¼•æŸ¥è¯¢ã€?br /> Term直接与QueryParser.parse里面的keyå’Œfield直接对应ã€?/p>

 IndexSearcher searcher = new IndexSearcher(directory);
 Term t = new Term("isbn", "1930110995");
 Query query = new TermQuery(t);
 Hits hits = searcher.search(query);

2.RangeQuery用于区间查询,RangeQuery的第三个参数表示是开区间˜q˜æ˜¯é—­åŒºé—´ã€?br /> QueryParser会构å»ÞZ»Žbegin到end之间的N个查询进行查询ã€?/p>

 Term begin, end;
 Searcher searcher = new IndexSearcher(dbpath);
 begin = new Term("pubmonth","199801");
 end = new Term("pubmonth","199810");
 RangeQuery query = new RangeQuery(begin, end, true);

RangeQuery本质是比较大ž®ã€‚所以如下查询也是可以的åQŒä½†æ˜¯æ„ä¹‰å°±äºŽä¸Šé¢ä¸å¤§ä¸€æ ·äº†åQŒæ€ÖM¹‹æ˜¯å¤§ž®çš„比较
讑֮šäº†ä¸€ä¸ªåŒºé—ß_¼Œåœ¨åŒºé—´å†…的都能够搜烦出来åQŒè¿™é‡Œå°±å­˜åœ¨ä¸€ä¸ªæ¯”较大ž®çš„原则åQŒæ¯”如字½W¦ä¸²ä¼šé¦–先比较第一个字½W¦ï¼Œ˜q™æ ·ä¸Žå­—½W¦é•¿åº¦æ²¡æœ‰å…³¾p…R€?br /> begin = new Term("pubmonth","19");
 end = new Term("pubmonth","20");
 RangeQuery query = new RangeQuery(begin, end, true);


3.PrefixQuery.对于TermQueryåQŒå¿…™åÕd®Œå…¨åŒ¹é…ï¼ˆç”¨Field.Keyword生成的字ŒDµï¼‰æ‰èƒ½å¤ŸæŸ¥è¯¢å‡ºæ¥ã€?br /> ˜q™å°±åˆ¶çº¦äº†æŸ¥è¯¢çš„灉|´»æ€§ï¼ŒPrefixQuery只需要匹配value的前面ä“Q何字ŒDµå³å¯ã€‚如Field为nameåQŒè®°å½?br /> 中那么有jackliu,jackwu,jackli,那么使用jackž®±å¯ä»¥æŸ¥è¯¢å‡ºæ‰€æœ‰çš„记录。QueryParser creates a PrefixQuery
for a term when it ends with an asterisk (*) in query expressions.

 IndexSearcher searcher = new IndexSearcher(directory);
 Term term = new Term("category", "/technology/computers/programming");
 PrefixQuery query = new PrefixQuery(term);
 Hits hits = searcher.search(query);

4.BooleanQuery.上面所有的查询都是åŸÞZºŽå•ä¸ªfield的查询，多个field怎么查询呢，BooleanQuery
ž®±æ˜¯è§£å†³å¤šä¸ªæŸ¥è¯¢çš„问题。通过add(Query query, boolean required, boolean prohibited)加入
多个查询.通过BooleanQuery的嵌套可以组合非常复杂的查询ã€?br />  
 IndexSearcher searcher = new IndexSearcher(directory);
 TermQuery searchingBooks =
 new TermQuery(new Term("subject","search"));

 RangeQuery currentBooks =
 new RangeQuery(new Term("pubmonth","200401"),
  new Term("pubmonth","200412"),true);
  
 BooleanQuery currentSearchingBooks = new BooleanQuery();
 currentSearchingBooks.add(searchingBook s, true, false);
 currentSearchingBooks.add(currentBooks, true, false);
 Hits hits = searcher.search(currentSearchingBooks);

BooleanQueryçš„addæ–ÒŽ³•æœ‰ä¸¤ä¸ªboolean参数åQ?br /> trueåQ†falseåQšè¡¨æ˜Žå½“前加入的子句是必™å»è¦æ»¡èƒöçš„ï¼›
falseåQ†trueåQšè¡¨æ˜Žå½“前加入的子句是不可以被满­‘³çš„åQ?br /> falseåQ†falseåQšè¡¨æ˜Žå½“前加入的子句是可选的åQ?br /> trueåQ†trueåQšé”™è¯¯çš„情况ã€?/p>

QueryParser handily constructs BooleanQuerys when multiple terms are specified.
Grouping is done with parentheses, and the prohibited and required flags are
set when the –, +, AND, OR, and NOT operators are specified.

5.PhraseQuery˜q›è¡Œæ›´äØ“¾_„¡¡®çš„查找。它能够对烦引文本中的两个或更多的关键词的位¾|®è¿›è¡?br /> 限定。如搜查包含Aå’ŒBòq¶ä¸”A、B之间˜q˜æœ‰ä¸€ä¸ªæ–‡å­—。Terms surrounded by double quotes in
QueryParser parsed expressions are translated into a PhraseQuery.
The slop factor defaults to zero, but you can adjust the slop factor
by adding a tilde (~) followed by an integer.
For example, the expression "quick fox"~3

6.WildcardQuery.WildcardQuery比PrefixQuery提供了更¾l†çš„控制和更大的灉|´»æ€§ï¼Œ˜q™ä¸ªæœ€å®ÒŽ˜“
理解和ä‹É用ã€?/p>

7.FuzzyQuery.˜q™ä¸ªQuery比较特别åQŒå®ƒä¼šæŸ¥è¯¢ä¸Žå…³é”®å­—长得很像的其他记录。QueryParser
supports FuzzyQuery by suffixing a term with a tilde (~),for exmaple wuzza~.

 public void testFuzzy() throws Exception {
  indexSingleFieldDocs(new Field[] {
  Field.Text("contents", "fuzzy"),
  Field.Text("contents", "wuzzy")
  });
  IndexSearcher searcher = new IndexSearcher(directory);
  Query query = new FuzzyQuery(new Term("contents", "wuzza"));
  Hits hits = searcher.search(query);
  assertEquals("both close enough", 2, hits.length());
  assertTrue("wuzzy closer than fuzzy",
  hits.score(0) != hits.score(1));
  assertEquals("wuzza bear","wuzzy", hits.doc(0).get("contents"));
 }