lucene 区分大小写 问题以及解决方案

转自：http://blog.csdn.net/huaishu/article/details/8543236

本文介绍lucene区分大小的原因,和解决方案.关于lucene大小写敏感问题我总结一下:

1.对于分词的Field且使用了StandardAnalyzer等分析器进行索引,同时利用StandardAnalyzer进行搜索时,lucene不区分大小写.

2.对于不分词的Field是区分大小写的. 

一.分词和不分词 

为了能使Field字段参与搜索,那么该Field就必须被索引.Field的Index类型必须是:(ANALYZED或TOKENIZED)和(NOT_ANALYZED或UN_TOKENIZED).区别在于:前者表示分词,后者表示不分词.例如:"中国人",使用StandardAnalyzer分析器分词结果是:"中","国","人".而不分词是把"中国人"作为整体建索引. 

二.StandardAnalyzer底层原理  

public override TokenStream TokenStream(System.String fieldName, System.IO.TextReader reader)
{
    TokenStream result = new StandardTokenizer(reader);
    result = new StandardFilter(result);
    result = new LowerCaseFilter(result);
    result = new StopFilter(result, stopSet);
    return result;
}

这是StandardAnalyzer类的一段代码.LowerCaseFilter可知StandardAnalyzer在分词时会有转小写的操作. 

建索引且分词时会被转小写. 

IndexSearcher searcher = new IndexSearcher("c:\java\index");

QueryParser parser = new QueryParser("title", new StandardAnalyzer());
Query query = parser.Parse(string.Format("title:{0}", key));

hits = searcher.Search(query);
printResult(hits, query.ToString());

这是段利用QueryParser和StandardAnalyzer的搜索,同样有转小写的操作.

由于建索引是底层小写,搜索也是被小写化了.故使用这种方式从外观接口的角度来说是不区分大小写的. 

三.不分词和TermQuery查询 

由于Field没有分词,所以建索引时数据会保持原始大小写. 

Hits hits = null;

IndexSearcher searcher = new IndexSearcher("c:\java\index");

TermQuery query = new TermQuery(new Term("name", key));

hits = searcher.Search(query);
printResult(hits, query.ToString());

这是一段使用TermQuery查询的方式.同样查询关键字是大写就大写,是小写就小写.

在这种使用情况下就会区分大小写.比如索引"abc",查询"Abc"就查不出来.

我的解决方案是:

建索引时小写化保存能,搜索时关键字小写化查询.

四.分词,不分词,StandardAnalyzer,TermQuery组合. 

1.不一定建索引时使用StandardAnalyzer,搜索时也时用StandardAnalyzer或不分词和TermQuery查询.其实有很多组合.

2.不仅StandardAnalyzer底层小写化,还有别的分析器也是这样的.或者可以自定义分析器. 

五.lucene区分大小写示例:  

using System;
using System.Collections.Generic;
using System.Text;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.Search;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.QueryParsers;

namespace IndexTest
{
    class Program
    {
        static void Main(string[] args)
        {
            createIndex();
            searchNameByTermQuery("abc");
            searchTitleByTermQuery("abc");

            searchNameByTermQuery("ABC");
            searchTitleByTermQuery("ABC");

            searchNameByQueryParser("ABC");
            searchTitleByQueryParser("ABC");

            //修改后的解决方案
            createIndex2();
            searchNameByTermQuery2("ABC");

            Console.ReadLine();
        }

        public static void createIndex()
        {
            Document doc1 = new Document();
            Field field = null;
            field = new Field("name", "abc", Field.Store.YES, Field.Index.UN_TOKENIZED);
            doc1.Add(field);
            field = new Field("title", "abc", Field.Store.YES, Field.Index.TOKENIZED);
            doc1.Add(field);
            field = new Field("id", "1", Field.Store.YES, Field.Index.NO);
            doc1.Add(field);

            Document doc2 = new Document();
            field = new Field("name", "Abc", Field.Store.YES, Field.Index.UN_TOKENIZED);
            doc2.Add(field);
            field = new Field("title", "Abc", Field.Store.YES, Field.Index.TOKENIZED);
            doc2.Add(field);
            field = new Field("id", "2", Field.Store.YES, Field.Index.NO);
            doc2.Add(field);


            IndexWriter writer = new IndexWriter("c:\java\index", new StandardAnalyzer(), true);

            writer.AddDocument(doc1);
            writer.AddDocument(doc2);


            writer.Close();
        }




        public static void searchNameByTermQuery(string key)
        {

            Hits hits = null;

            IndexSearcher searcher = new IndexSearcher("c:\java\index");

            TermQuery query = new TermQuery(new Term("name", key));

            hits = searcher.Search(query);
            printResult(hits, query.ToString());
        }

        public static void searchTitleByTermQuery(string key)
        {

            Hits hits = null;

            IndexSearcher searcher = new IndexSearcher("c:\java\index");

            TermQuery query = new TermQuery(new Term("title", key));

            hits = searcher.Search(query);
            printResult(hits, query.ToString());
        }

        public static void searchNameByQueryParser(string key)
        {

            Hits hits = null;
            IndexSearcher searcher = new IndexSearcher("c:\java\index");

            QueryParser parser = new QueryParser("name", new StandardAnalyzer());
            Query query = parser.Parse(string.Format("name:{0}",key));

            hits = searcher.Search(query);
            printResult(hits, query.ToString());
        }

        public static void searchTitleByQueryParser(string key)
        {

            Hits hits = null;

            IndexSearcher searcher = new IndexSearcher("c:\java\index");

            QueryParser parser = new QueryParser("title", new StandardAnalyzer());
            Query query = parser.Parse(string.Format("title:{0}", key));

            hits = searcher.Search(query);
            printResult(hits, query.ToString());
        }



        public static void createIndex2()
        {
            Document doc1 = new Document();
            Field field = null;
            field = new Field("name", "abc".ToLower(), Field.Store.YES, Field.Index.UN_TOKENIZED);
            doc1.Add(field);
            field = new Field("title", "abc", Field.Store.YES, Field.Index.TOKENIZED);
            doc1.Add(field);
            field = new Field("id", "1", Field.Store.YES, Field.Index.NO);
            doc1.Add(field);

            Document doc2 = new Document();
            field = new Field("name", "Abc".ToLower(), Field.Store.YES, Field.Index.UN_TOKENIZED);
            doc2.Add(field);
            field = new Field("title", "Abc", Field.Store.YES, Field.Index.TOKENIZED);
            doc2.Add(field);
            field = new Field("id", "2", Field.Store.YES, Field.Index.NO);
            doc2.Add(field);


            IndexWriter writer = new IndexWriter("c:\java\index", new StandardAnalyzer(), true);

            writer.AddDocument(doc1);
            writer.AddDocument(doc2);


            writer.Close();
        }

        public static void searchNameByTermQuery2(string key)
        {

            Hits hits = null;

            IndexSearcher searcher = new IndexSearcher("c:\java\index");

            TermQuery query = new TermQuery(new Term("name", key.ToLower()));

            hits = searcher.Search(query);
            printResult(hits, query.ToString());
        }



         public static void printResult(Hits hits, String key)
     {
         Console.WriteLine("查询 " + key);
         if (hits != null)
         {
             if (hits.Length() == 0)
             {
                 Console.WriteLine("没有找到任何结果");
             }
             else
             {
                 Console.WriteLine("找到" + hits.Length() + "个结果");
                 for (int i = 0; i < hits.Length(); i++)
                 {
                     Document d = hits.Doc(i);
                     String id = d.Get("id");
                     Console.WriteLine(id.ToString() + "   ");
                 }
                 Console.WriteLine();
             }
         }
     }
 }

}

 

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