关于Solr1.4和paoding分词器整合的一个需要注意的问题

今天有人说在Solr1.4里使用paoding2.0.4(可能是终结版了)，无法实现正常的高亮显示。这个问题说难不难，说简单也不简单，我上次配置的时候，也花了一点时间测试，才找对合适的参数。今天既然有人问起来，我干脆在这里简单写一下，免得以后忘记。

闲话少叙，开始干活。

在Solr1.4出来之前，Paoding就已经停止开发了，所以Paoding分词器没有考虑与Solr1.4整合的功能，值得庆幸的是在网上，有前辈已经给我们铺了一条比较平坦的路了，具体讲，就是Bory.Chan前辈给我们封装了一个工厂类，通过使用这个工厂类，就可以比较简单地实现Solr1.4和paoding的友好相处。这个工厂类的源码我就不贴了，贴个地址，表示对前辈的尊重：http://blog.chenlb.com/2009/12/solr-1-4-with-paoding.html

下载这个工厂类，编译。

然后再修改solr/conf/schemal.xml文件，在其中找到这一段：

    <fieldType name="text" class="solr.TextField" positionIncrementGap="100">
      <analyzer type="index">
        <tokenizer class="solr.WhitespaceTokenizerFactory"/>

        <!-- in this example, we will only use synonyms at query time
        <filter class="solr.SynonymFilterFactory" synonyms="index_synonyms.txt" ignoreCase="true" expand="false"/>
        -->
        <!-- Case insensitive stop word removal.
          add enablePositionIncrements=true in both the index and query
          analyzers to leave a 'gap' for more accurate phrase queries.
        -->
        <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
        <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="1" catenateNumb
ers="1" catenateAll="0" splitOnCaseChange="1"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="solr.SnowballPorterFilterFactory" language="English" protected="protwords.txt"/>
      </analyzer>
      <analyzer type="query">
        <tokenizer class="solr.WhitespaceTokenizerFactory"/>

        <filter class="solr.SynonymFilterFactory" synonyms="synonyms.txt" ignoreCase="true" expand="true"/>
        <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
        <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="0" catenateNumb
ers="0" catenateAll="0" splitOnCaseChange="1"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="solr.SnowballPorterFilterFactory" language="English" protected="protwords.txt"/>
      </analyzer>
    </fieldType>

改成如下：

    <fieldType name="text" class="solr.TextField" positionIncrementGap="100">
      <analyzer type="index">
        <tokenizer class="com.chenlb.solr.paoding.PaodingTokenizerFactory" />

        <!-- in this example, we will only use synonyms at query time
        <filter class="solr.SynonymFilterFactory" synonyms="index_synonyms.txt" ignoreCase="true" expand="false"/>
        -->
        <!-- Case insensitive stop word removal.
          add enablePositionIncrements=true in both the index and query
          analyzers to leave a 'gap' for more accurate phrase queries.
        -->
        <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
        <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="1" catenateNumb
ers="1" catenateAll="0" splitOnCaseChange="1"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="solr.SnowballPorterFilterFactory" language="English" protected="protwords.txt"/>
      </analyzer>
      <analyzer type="query">
        <tokenizer class="com.chenlb.solr.paoding.PaodingTokenizerFactory" mode="max-word-length"/>
        <filter class="solr.SynonymFilterFactory" synonyms="synonyms.txt" ignoreCase="true" expand="true"/>
        <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
        <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="0" catenateNumb
ers="0" catenateAll="0" splitOnCaseChange="1"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="solr.SnowballPorterFilterFactory" language="English" protected="protwords.txt"/>
      </analyzer>
    </fieldType>

 要注意的是，Bory.Chan给的例子是在“index”配置中，设置mode="max-word-length"，而在“query”则不设置，经过我实际测试，发现这两个参数位置互换一下才能达到比较好的效果。

另外，这个工厂类只支持“max-word-length”和“非max-word-length”两种模式，而“max-word-length”这个单词容易写错了，所以我改造了一下PaodingTokenizerFactory，把这个参数设置成一个boolean型的参数。

import java.io.Reader;
import java.util.Map;

import net.paoding.analysis.analyzer.PaodingTokenizer;
import net.paoding.analysis.analyzer.TokenCollector;
import net.paoding.analysis.analyzer.impl.MaxWordLengthTokenCollector;
import net.paoding.analysis.analyzer.impl.MostWordsTokenCollector;
import net.paoding.analysis.knife.PaodingMaker;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.solr.analysis.BaseTokenizerFactory;

import cn.com.pansky.otp3.lucene.analyzer.paoding.SolrPaodingTokenizer;

/**
 * 基于Paoding分词器的分词工厂
 * @author http://blog.chenlb.com/
 * @Modified by BrokenStone 2010-08-03
 *
 */
public class PaodingTokenizerFactory extends BaseTokenizerFactory {

        public static final String MOST_WORDS_MODE = "most-words";            //最多切分 默认模式
        public static final String MAX_WORD_LENGTH_MODE = "max-word-length";  //按最大切分

        private boolean isMaxWordLength = false;     //是否采用“按最大切分”模式分词，默认是按“最多切分”模式分词
        public boolean isMaxWordLength() {
                return isMaxWordLength;
        }

        public void setMaxWordLength(boolean isMaxWordLength) {
                this.isMaxWordLength = isMaxWordLength;
        }


        public Tokenizer create(Reader input) {
                return new SolrPaodingTokenizer(input, PaodingMaker.make(),
                                createTokenCollector());
        }

        private TokenCollector createTokenCollector() {
                if(isMaxWordLength)
                        return new MaxWordLengthTokenCollector();
                else
                        return new MostWordsTokenCollector();
        }
}