今尝试下给nutch1.2增加一个插件,于是到官网找了个例子,链接如下:

http://wiki.apache.org/nutch/WritingPluginExample-0.9

这个例子实现的的是推荐网站,就是写关键字在content里,当别人搜索这个关键字时,你推荐的网站在搜索结果中排前,要实现推荐必须在你的网页上加上

<meta name="recommended" content="plugins" />

这条属性才能被插件识别。

由于它这个例子是用nutch0.9的,而且1.2和0.9有些区别,于是要修改一些代码。步骤如下:

1.插件开放

1.1在src/plugin中新建一个文件夹recommend

1.2.在recommend目录下新建Plugin.xml和Build.xml文件,内容如下:

Plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<plugin
   id="recommended"
   name="Recommended Parser/Filter"
   version="0.0.1"
   provider-name="nutch.org">

   <runtime>
      <!-- As defined in build.xml this plugin will end up bundled as recommended.jar -->
      <library name="recommended.jar">
         <export name="*"/>
      </library>
   </runtime>

   <!-- The RecommendedParser extends the HtmlParseFilter to grab the contents of
        any recommended meta tags -->
   <extension id="org.apache.nutch.parse.recommended.recommendedfilter"
              name="Recommended Parser"
              point="org.apache.nutch.parse.HtmlParseFilter">
      <implementation id="RecommendedParser"
                      class="org.apache.nutch.parse.recommended.RecommendedParser"/>
   </extension>

   <!-- TheRecommendedIndexer extends the IndexingFilter in order to add the contents
        of the recommended meta tags (as found by the RecommendedParser) to the lucene
        index. -->
   <extension id="org.apache.nutch.parse.recommended.recommendedindexer"
              name="Recommended identifier filter"
              point="org.apache.nutch.indexer.IndexingFilter">
      <implementation id="RecommendedIndexer"
                      class="org.apache.nutch.parse.recommended.RecommendedIndexer"/>
   </extension>

   <!-- The RecommendedQueryFilter gets called when you perform a search. It runs a
        search for the user's query against the recommended fields.  In order to get
        add this to the list of filters that gets run by default, you have to use
        "fields=DEFAULT". -->   
   <extension id="org.apache.nutch.parse.recommended.recommendedSearcher"
              name="Recommended Search Query Filter"
              point="org.apache.nutch.searcher.QueryFilter">
      <implementation id="RecommendedQueryFilter"
                      class="org.apache.nutch.parse.recommended.RecommendedQueryFilter">
        <parameter name="fields" value="recommended"/>
        </implementation>
   </extension>

</plugin>

Build.xml

<?xml version="1.0"?>

<project name="recommended" default="jar-core">

  <import file="../build-plugin.xml"/>
  
 <!-- Build compilation dependencies -->
 <target name="deps-jar">
   <ant target="jar" inheritall="false" dir="../lib-xml"/>
 </target>

  <!-- Add compilation dependencies to classpath -->
 <path id="plugin.deps">
   <fileset dir="${nutch.root}/build">
     <include name="**/lib-xml/*.jar" />
   </fileset>
 </path>

  <!-- Deploy Unit test dependencies -->
 <target name="deps-test">
   <ant target="deploy" inheritall="false" dir="../lib-xml"/>
   <ant target="deploy" inheritall="false" dir="../nutch-extensionpoints"/>
   <ant target="deploy" inheritall="false" dir="../protocol-file"/>
 </target>

 
  <!-- for junit test -->
  <mkdir dir="${build.test}/data"/>
  <copy file="data/recommended.html" todir="${build.test}/data"/>
</project>

1.3.在recommended目录下建立/src/java/org/apache/nutch/parse/recommended目录。

1.4.增加RecommendedIndexer.java,RecommendedParser.java,RecommendedQueryFilter.java三个类,内容如下:

RecommendedIndexer.java

package org.apache.nutch.parse.recommended;

// JDK import
import java.util.logging.Logger;

// Commons imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


// Nutch imports
import org.apache.nutch.util.LogUtil;
import org.apache.nutch.fetcher.FetcherOutput;
import org.apache.nutch.indexer.IndexingFilter;
import org.apache.nutch.indexer.IndexingException;
import org.apache.nutch.indexer.NutchDocument;
import org.apache.nutch.parse.Parse;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.crawl.Inlinks;

// Lucene imports
import org.apache.lucene.document.Field;
import org.apache.lucene.document.Document;

public class RecommendedIndexer implements IndexingFilter {
    
  public static final Log LOG = LogFactory.getLog(RecommendedIndexer.class.getName());
  
  private Configuration conf;
  
  public RecommendedIndexer() {
  }
  @Override
  public NutchDocument filter(NutchDocument doc, Parse parse, Text url, 
    CrawlDatum datum, Inlinks inlinks)
    throws IndexingException {

    String recommendation = parse.getData().getMeta("recommended");

        if (recommendation != null) {
            Field recommendedField = 
                new Field("recommended", recommendation, 
                    Field.Store.YES, Field.Index.NOT_ANALYZED);
            recommendedField.setBoost(5.0f);
            doc.add("recommended",recommendedField);
            LOG.info("Added " + recommendation + " to the recommended Field");
        }

    return doc;
  }
  
  public void setConf(Configuration conf) {
    this.conf = conf;
  }

  public Configuration getConf() {
    return this.conf;
  }

@Override
public void addIndexBackendOptions(Configuration conf) {
	// TODO Auto-generated method stub
}
}

RecommendedParser.java

package org.apache.nutch.parse.recommended;

// JDK imports
import java.util.Enumeration;
import java.util.Properties;
import java.util.logging.Logger;

// Nutch imports
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.metadata.Metadata;
import org.apache.nutch.parse.HTMLMetaTags;
import org.apache.nutch.parse.Parse;
import org.apache.nutch.parse.HtmlParseFilter;
import org.apache.nutch.parse.ParseResult;
import org.apache.nutch.protocol.Content;

// Commons imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

// W3C imports
import org.w3c.dom.DocumentFragment;

public class RecommendedParser implements HtmlParseFilter {

  private static final Log LOG = LogFactory.getLog(RecommendedParser.class.getName());
  
  private Configuration conf;

  /** The Recommended meta data attribute name */
  public static final String META_RECOMMENDED_NAME="recommended";

  /**
   * Scan the HTML document looking for a recommended meta tag.
   */
  
  @Override
  public ParseResult filter(Content content, ParseResult parseResult,
    HTMLMetaTags metaTags, DocumentFragment doc) {
    // Trying to find the document's recommended term
    String recommendation = null;

    Properties generalMetaTags = metaTags.getGeneralTags();

    for (Enumeration tagNames = generalMetaTags.propertyNames(); tagNames.hasMoreElements(); ) {
        if (tagNames.nextElement().equals("recommended")) {
            System.out.println(generalMetaTags.getProperty("recommended"));
        	recommendation = generalMetaTags.getProperty("recommended");
           LOG.info("Found a Recommendation for " + recommendation);
        }
    }

    if (recommendation == null) {
        LOG.info("No Recommendation");
    } else {
        LOG.info("Adding Recommendation for " + recommendation);
        Parse parse = parseResult.get(content.getUrl());
        
        parse.getData().getContentMeta().set(META_RECOMMENDED_NAME, recommendation);
    }

    return parseResult;
  }
  
  public void setConf(Configuration conf) {
    this.conf = conf;
  }

  public Configuration getConf() {
    return this.conf;
  }



}

RecommendedQueryFilter.java

package org.apache.nutch.parse.recommended;

import org.apache.nutch.searcher.FieldQueryFilter;

import java.util.logging.Logger;

// Commons imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


public class RecommendedQueryFilter extends FieldQueryFilter {
    private static final Log LOG = LogFactory.getLog(RecommendedParser.class.getName());

    public RecommendedQueryFilter() {
        super("recommended", 5f);
        LOG.info("Added a recommended query");
    }
  
}

1.5.在 src/plugin/build.xml 中的<target name="deploy"></target>中增加一行:

<ant dir="recommended" target="deploy" />

1.6.运行cmd,切换到recommend目录,运行ant命令编译,插件开发完成。

1.7 让nutch识别你的插件

      在conf/nutch-site.xml 中增加一下属性

<property>
  <name>plugin.includes</name>
  <value>recommended|protocol-http|urlfilter-regex|parse-(text|html|js)|index-basic|query-(basic|site|url)|summary-basic|scoring-opic|urlnormalizer-(pass|regex|basic)</value>  <description>Regular expression naming plugin id names to
  include.  Any plugin not matching this expression is excluded.
  In any case you need at least include the nutch-extensionpoints plugin. By
  default Nutch includes crawling just HTML and plain text via HTTP,
  and basic indexing and search plugins.
  </description>
</property>

2.编写插件测试类

2.1 在src/plugin中/recommend目录下新建一个data目录,在data目录下新建一个html文件recommended.html内容如下:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">

<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>recommended</title>
    <meta name="generator" content="TextMate http://macromates.com/">
    <meta name="author" content="Ricardo J. Méndez">
    <meta name="recommended" content="recommended-content"/>
    <!-- Date: 2007-02-12 -->
</head>
<body>
    Recommended meta tag test.
</body>
</html>

2.2 在src/plugin中/recommend目录下新建src/test/org/apache/nutch/parse/recommended目录,增加TestRecommendedParser.java类,内容如下:

package org.apache.nutch.parse.recommended;


import org.apache.nutch.metadata.Metadata;
import org.apache.nutch.parse.Parse;
import org.apache.nutch.parse.ParseResult;
import org.apache.nutch.parse.ParseUtil;
import org.apache.nutch.protocol.Content;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.util.NutchConfiguration;

import java.util.Properties;
import java.io.*;
import java.net.URL;

import junit.framework.TestCase;

/*
 * Loads test page recommended.html and verifies that the recommended 
 * meta tag has recommended-content as its value.
 *
 */
public class TestRecommendedParser extends TestCase {

  private static final File testDir =
    new File("H:/project/SearchEngine/Nutch1.2/src/plugin/recommended/data");

  public void testPages() throws Exception {
    pageTest(new File(testDir, "recommended.html"), "http://foo.com/",
             "recommended-content");

  }


  public void pageTest(File file, String url, String recommendation)
    throws Exception {

    String contentType = "text/html";
    InputStream in = new FileInputStream(file);
    
    ByteArrayOutputStream out = new ByteArrayOutputStream((int)file.length());
    byte[] buffer = new byte[1024];
    int i;
    while ((i = in.read(buffer)) != -1) {
      out.write(buffer, 0, i);
    }
    in.close();
    byte[] bytes = out.toByteArray();
    Configuration conf = NutchConfiguration.create();

    Content content =
      new Content(url, url, bytes, contentType, new Metadata(), conf);
    
    Parse parse = new ParseUtil(conf).parseByExtensionId("parse-html",content).get(content.getUrl());
    
    Metadata metadata = parse.getData().getContentMeta();
  
    assertEquals(recommendation, metadata.get("recommended"));
    assertTrue("somesillycontent" != metadata.get("recommended"));
  }
  
}

2.3 用junit运行TestRecommendedParser.java测试。

                                                                                                                                                                       2010-10-09