【Neo4j】踩坑大会-Neo4J用中文索引

正在用的Neo4j是当前最新版：3.1.0，各种踩坑。说一下如何在Neo4j 3.1.0中使用中文索引。选用了IKAnalyzer做分词器。

1. 首先参考文章：

https://segmentfault.com/a/1190000005665612

里面大致讲了用IKAnalyzer做索引的方式。但并不清晰，实际上，这篇文章的背景是用嵌入式Neo4j，即Neo4j一定要嵌入在你的Java应用中（https://neo4j.com/docs/java-reference/current/#tutorials-java-embedded），切记。否则无法使用自定义的Analyzer。其次，文中的方法现在用起来已经有问题了，因为Neo4j 3.1.0用了lucene5.5，故官方的IKAnalyzer已经不适用了。

2. 修正

转用 IKAnalyzer2012FF_u1.jar，在Google可以下载到（https://code.google.com/archive/p/ik-analyzer/downloads）。这个版本的IKAnalyzer是有小伙伴修复了IKAnalyzer不适配lucene3.5以上而修改的一个版本。但是用了这个包仍有问题，报错提示：

Caused by: java.lang.AbstractMethodError: org.apache.lucene.analysis.Analyzer.createComponents(Ljava/lang/String;)Lorg/apache/lucene/analysis/Analyzer$TokenStreamComponents;

即IKAnalyzer的Analyzer类和当前版本的lucene仍有不适配的地方。

解决方案：再增加两个类

package com.uc.wa.function;





 





import org.apache.lucene.analysis.Analyzer;





import org.apache.lucene.analysis.Tokenizer;





 





public class IKAnalyzer5x extends Analyzer{





 





    private boolean useSmart;





    





    public boolean useSmart() {





     return useSmart;





  }





 





  public void setUseSmart(boolean useSmart) {





       this.useSmart = useSmart;





 }





 





  public IKAnalyzer5x(){





        this(false);





    }





   





    public IKAnalyzer5x(boolean useSmart){





      super();





      this.useSmart = useSmart;





 }





 





  





    /**





  protected TokenStreamComponents createComponents(String fieldName, final Reader in) {





     Tokenizer _IKTokenizer = new IKTokenizer(in , this.useSmart());





       return new TokenStreamComponents(_IKTokenizer);





   }





 **/





  





    





    /**





     * 重写最新版本的createComponents





     * 重载Analyzer接口，构造分词组件





     */





    @Override





    protected TokenStreamComponents createComponents(String fieldName) {





      Tokenizer _IKTokenizer = new IKTokenizer5x(this.useSmart());





        return new TokenStreamComponents(_IKTokenizer);





 }





}

package com.uc.wa.function;





 





import java.io.IOException;





 





import org.apache.lucene.analysis.Tokenizer;





import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;





import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;





import org.apache.lucene.analysis.tokenattributes.TypeAttribute;





import org.wltea.analyzer.core.IKSegmenter;





import org.wltea.analyzer.core.Lexeme;





 





public class IKTokenizer5x extends Tokenizer{





    





    //IK�ִ���ʵ��





    private IKSegmenter _IKImplement;





     





    //��Ԫ�ı�����





    private final CharTermAttribute termAtt;





    //��Ԫλ������





    private final OffsetAttribute offsetAtt;





    //��Ԫ�������ԣ������Է���ο�org.wltea.analyzer.core.Lexeme�еķ��ೣ����





    private final TypeAttribute typeAtt;





    //��¼���һ����Ԫ�Ľ���λ��





    private int endPosition;





     





     





    /**





    public IKTokenizer(Reader in , boolean useSmart){





        super(in);





        offsetAtt = addAttribute(OffsetAttribute.class);





        termAtt = addAttribute(CharTermAttribute.class);





        typeAtt = addAttribute(TypeAttribute.class);





        _IKImplement = new IKSegmenter(input , useSmart);





    }**/





     





    /**





     * Lucene 5.x Tokenizer�������๹�캯��





     * ʵ�����µ�Tokenizer�ӿ�





     * @param useSmart





     */





    public IKTokenizer5x(boolean useSmart){





        super();





        offsetAtt = addAttribute(OffsetAttribute.class);





        termAtt = addAttribute(CharTermAttribute.class);





        typeAtt = addAttribute(TypeAttribute.class);





        _IKImplement = new IKSegmenter(input , useSmart);





    }





 





    /* (non-Javadoc)





     * @see org.apache.lucene.analysis.TokenStream#incrementToken()





     */





    @Override





    public boolean incrementToken() throws IOException {





        //������еĴ�Ԫ����





        clearAttributes();





        Lexeme nextLexeme = _IKImplement.next();





        if(nextLexeme != null){





            //��Lexemeת��Attributes





            //���ô�Ԫ�ı�





            termAtt.append(nextLexeme.getLexemeText());





            //���ô�Ԫ����





            termAtt.setLength(nextLexeme.getLength());





            //���ô�Ԫλ��





            offsetAtt.setOffset(nextLexeme.getBeginPosition(), nextLexeme.getEndPosition());





            //��¼�ִʵ����λ��





            endPosition = nextLexeme.getEndPosition();





            //��¼��Ԫ����





            typeAtt.setType(nextLexeme.getLexemeTypeString());          





            //����true��֪�����¸���Ԫ





            return true;





        }





        //����false��֪��Ԫ������





        return false;





    }





     





    /*





     * (non-Javadoc)





     * @see org.apache.lucene.analysis.Tokenizer#reset(java.io.Reader)





     */





    @Override





    public void reset() throws IOException {





        super.reset();





        _IKImplement.reset(input);





    }   





     





    @Override





    public final void end() {





        // set final offset





        int finalOffset = correctOffset(this.endPosition);





        offsetAtt.setOffset(finalOffset, finalOffset);





    }





}

解决 IKAnalyzer2012FF_u1.jar和lucene5不适配的问题。使用时用IKAnalyzer5x替换IKAnalyzer即可。

3. 最后

Neo4j中文索引建立和搜索示例：

    /**





   * 为单个结点创建索引





  * 





   * @param propKeys





    */





  public static void createFullTextIndex(long id, List<String> propKeys) {





      log.info("method[createFullTextIndex] begin.propKeys<"+propKeys+">");





     Index<Node> entityIndex = null;





      





        try (Transaction tx = Neo4j.graphDb.beginTx()) {





            entityIndex = Neo4j.graphDb.index().forNodes("NodeFullTextIndex",





                  MapUtil.stringMap(IndexManager.PROVIDER, "lucene", "analyzer", IKAnalyzer5x.class.getName()));





          





            Node node = Neo4j.graphDb.getNodeById(id);





          log.info("method[createFullTextIndex] get node id<"+node.getId()+"> name<"





                    +node.getProperty("knowledge_name")+">");





          /**获取node详细信息*/





         Set<Map.Entry<String, Object>> properties = node.getProperties(propKeys.toArray(new String[0]))





                  .entrySet();





            for (Map.Entry<String, Object> property : properties) {





                log.info("method[createFullTextIndex] index prop<"+property.getKey()+":"+property.getValue()+">");





              entityIndex.add(node, property.getKey(), property.getValue());





          }





           tx.success();





       }





   }

    /**





    * 使用索引查询





   * 





     * @param query





     * @return





  * @throws IOException 





     */





   public static List<Map<String, Object>> selectByFullTextIndex(String[] fields, String query) throws IOException {





        List<Map<String, Object>> ret = Lists.newArrayList();





     try (Transaction tx = Neo4j.graphDb.beginTx()) {





          IndexManager index = Neo4j.graphDb.index();





         /**查询*/





           Index<Node> addressNodeFullTextIndex = index.forNodes("NodeFullTextIndex",





                   MapUtil.stringMap(IndexManager.PROVIDER, "lucene", "analyzer", IKAnalyzer5x.class.getName()));





            Query q = IKQueryParser.parseMultiField(fields, query);





         





            IndexHits<Node> foundNodes = addressNodeFullTextIndex.query(q);





 





          for(Node n : foundNodes){





             Map<String, Object> m = n.getAllProperties();





                if(!Float.isNaN(foundNodes.currentScore())){





                  m.put("score", foundNodes.currentScore());





             }





               log.info("method[selectByIndex] score<"+foundNodes.currentScore()+">");





             ret.add(m);





         }





           tx.success();





       } catch (IOException e) {





         log.error("method[selectByIndex] fields<"+Joiner.on(",").join(fields)+"> query<"+query+">", e);





         throw e;





      }





       return ret;





   }

注意到，在这里我用了IKQueryParser，即根据我们的查询词和要查询的字段，自动构造Query。这里是绕过了一个坑：用lucene查询语句直接查的话，是有问题的。比如：“address:南昌市” 查询语句，会搜到所有带市字的地址，这是非常不合理的。改用IKQueryParser即修正这个问题。IKQueryParser是IKAnalyzer自带的一个工具，但在 IKAnalyzer2012FF_u1.jar却被删减掉了。因此我这里重新引入了原版IKAnalyzer的jar包，项目最终是两个jar包共存的。

到这里坑就踩得差不多了。

       原文地址：https://blog.csdn.net/hereiskxm/article/details/54345261                         </div>