分词系统建立完毕，这是基础也是核心，后面我们建立索引要用到分词系统。
下面依次讲解索引的建立，索引的查找。
分词系统建立完毕，这是基础也是核心，后面我们建立索引要用到分词系统。下面依次讲解索引的建立，索引的查找。
索引的建立采用的是倒排序，原理就是遍历所有的文本，对其进行分词，然后把分的词汇建立索引表。形式类似如下：
词汇 出现词汇的篇章1，篇章2，篇章3……
建立索引的时候要注意这样的Document，Field这俩术语。Document代表的是一个文档，它里面包含一个或者多个Filed，Field表示的就是一种域，你可以在一个Document里面添加各种各样的域，名字自己起，但是关于文档的内容一定要加进去，方式如下所示：
doc.Add(new Field("contents", str, Field.Store.YES, Field.Index.ANALYZED,Field.TermVector.WITH_POSITIONS_OFFSETS));
整个索引的建立如下所示：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Index;
using Lucene.Net.Documents;
using Lucene.Net.Search;
using Lucene.Net.Analysis.DChinese;
using Version = Lucene.Net.Util.Version;
using FSDirectory = Lucene.Net.Store.FSDirectory;
using NativeFSLockFactory = Lucene.Net.Store.NativeFSLockFactory;
namespace WebApplication6
{
public class IndexFiles
{
public static bool CreateIndexFromFile(DirectoryInfo docDir, DirectoryInfo IndexDir)
{
string strUserDicPath = System.AppDomain.CurrentDomain.BaseDirectory;
string strTestDic = strUserDicPath;
HashSet<string> lstStopWords = new HashSet<string>();
strUserDicPath = strUserDicPath + "UserDictionary\\StopWords.txt";
string[] strs = null;
StreamWriter sw = new StreamWriter(strTestDic + "UserDictionary\\StopTest.txt");
using (StreamReader strReader = new StreamReader(strUserDicPath))
{
string strLine;
while ((strLine = strReader.ReadLine()) != null)
{
strLine = strLine.Trim();
strs = strLine.Split();
foreach (string str in strs)
{
lstStopWords.Add(str);
sw.WriteLine(str);
}
}
strReader.Close();
sw.Close();
}
bool bExist = File.Exists(docDir.FullName) || Directory.Exists(docDir.FullName);
if (!bExist)
{
return false;
}
//using (IndexWriter writer = new IndexWriter(FSDirectory.Open(IndexDir), new DChineseAnalyzer(Version.LUCENE_30), true, IndexWriter.MaxFieldLength.LIMITED) )
//IndexWriter writer = new IndexWriter(fsDirrctory, new StandardAnalyzer(Version.LUCENE_30), true, IndexWriter.MaxFieldLength.LIMITED);
FSDirectory fsDirrctory = FSDirectory.Open(IndexDir, new NativeFSLockFactory());
Analyzer analyzer = new DChineseAnalyzer(Version.LUCENE_30,lstStopWords);
IndexWriter writer = new IndexWriter(fsDirrctory, analyzer, true, IndexWriter.MaxFieldLength.LIMITED);
try
{
IndexDirectory(writer, docDir);
writer.Optimize();
writer.Commit();
}
finally
{
writer.Dispose();
fsDirrctory.Dispose();
}
return true;
}
internal static void IndexDirectory(IndexWriter writer, DirectoryInfo directory)
{
foreach (var subDirectory in directory.GetDirectories())
IndexDirectory(writer, subDirectory);
foreach (var file in directory.GetFiles())
IndexDocs(writer, file);
}
internal static void IndexDocs(IndexWriter writer, FileInfo file)
{
Console.Out.WriteLine("adding " + file);
try
{
writer.AddDocument(Document(file));
}
catch (FileNotFoundException)
{
// At least on Windows, some temporary files raise this exception with an
// "access denied" message checking if the file can be read doesn't help.
}
catch (UnauthorizedAccessException)
{
// Handle any access-denied errors that occur while reading the file.
}
catch (IOException)
{
// Generic handler for any io-related exceptions that occur.
}
}
public static Document Document(FileInfo f)
{
// make a new, empty document
Document doc = new Document();
// Add the path of the file as a field named "path". Use a field that is
// indexed (i.e. searchable), but don't tokenize the field into words.
doc.Add(new Field("path", f.FullName, Field.Store.YES, Field.Index.NOT_ANALYZED));
// Add the last modified date of the file a field named "modified". Use
// a field that is indexed (i.e. searchable), but don't tokenize the field
// into words.
doc.Add(new Field("modified", DateTools.TimeToString(f.LastWriteTime.Millisecond, DateTools.Resolution.MINUTE), Field.Store.YES, Field.Index.NOT_ANALYZED));
// Add the contents of the file to a field named "contents". Specify a Reader,
// so that the text of the file is tokenized and indexed, but not stored.
// Note that FileReader expects the file to be in the system's default encoding.
// If that's not the case searching for special characters will fail.
string str = File.ReadAllText(f.FullName);
//doc.Add(new Field("contents", new StreamReader(f.FullName, System.Text.Encoding.UTF8)));
doc.Add(new Field("contents", str, Field.Store.YES, Field.Index.ANALYZED, Field.TermVector.WITH_POSITIONS_OFFSETS));
// return the document
return doc;
}
}
}
查找的实现：
Lucene.net中有多种多样的查找类，但是如果要实现多条件查询就要使用PhraseQuery
类。通过搜索函数把搜索结果放到容器里面。
最后结果的呈现时候，我们把搜索结果放到列表里面，如果还要显示关键词加亮，那么就需要做一点额外的工作。在这里我是通过ColorWord这个类实现的。具体的搜索代码如下所示：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.DChinese;
using Lucene.Net.Documents;
using Lucene.Net.QueryParsers;
using Lucene.Net.Index;
using Lucene.Net.Search;
using FSDirectory = Lucene.Net.Store.FSDirectory;
using NoLockFactory = Lucene.Net.Store.NoLockFactory;
using Version = Lucene.Net.Util.Version;
namespace WebApplication6
{
public static class SearchFiles
{
public static List<ItemList> SearchIndex(DirectoryInfo dirIndex, List<string> termList)
{
FSDirectory dirFS = FSDirectory.Open(dirIndex, new NoLockFactory());
IndexReader reader = IndexReader.Open(dirFS,true);
IndexSearcher searcher = new IndexSearcher(reader);
Analyzer analyzer = new DChineseAnalyzer(Version.LUCENE_30);
PhraseQuery query = new PhraseQuery();
foreach (string word in termList)
{
query.Add( new Term("contents",word) );
}
query.Slop = 100;
TopScoreDocCollector collector = TopScoreDocCollector.Create(1000, true);
searcher.Search(query,collector);
ScoreDoc[] hits = collector.TopDocs().ScoreDocs;
List<ItemList> lstResult = new List<ItemList>();
for (int i = 0; i < hits.Length; i++)
{
Document doc = new Document();
doc = searcher.Doc(hits[i].Doc);
ItemList item = new ItemList();
//item.ItemContent = doc.Get("contents");
item.ItemContent = ColorWord.addColor(doc.Get("contents"),termList);
item.ItemPath = doc.Get("path");
lstResult.Add(item);
}
return lstResult;
}
}
}
最终的效果展示如下所示：
最终的代码下载地址:下载