Lucene 是apache軟件基金會一個開放源代碼的全文檢索引擎工具包，是一個全文檢索引擎的架構，提供了完整的查詢引擎和索引引擎，部分文本分析引擎。Lucene的目的是為軟件開發人員提供一個簡單易用的工具包，以方便的在目標系統中實現全文檢索的功能，或者是以此為基礎建立起完整的全文檢索引擎。Lucene.Net 是 .NET 版的Lucene。
using System;
using Lucene.Net.Store;
using Lucene.Net.Index;
using Lucene.Net.Analysis.PanGu;
using Lucene.Net.Documents;
namespace BLL
{
class IndexHelper
{
/// summary>
/// 日志小助手
/// /summary>
static Common.LogHelper logger = new Common.LogHelper(typeof(SearchBLL));
/// summary>
/// 索引保存的位置，保存在配置文件中從配置文件讀取
/// /summary>
static string indexPath = Common.ConfigurationHelper.AppSettingMapPath("IndexPath");
/// summary>
/// 創建索引文件或更新索引文件
/// /summary>
/// param name="item">索引信息/param>
public static void CreateIndex(Model.HelperModel.IndexFileHelper item)
{
try
{
//索引存儲庫
FSDirectory directory = FSDirectory.Open(new System.IO.DirectoryInfo(indexPath), new NativeFSLockFactory());
//判斷索引是否存在
bool isUpdate = IndexReader.IndexExists(directory);
if (isUpdate)
{
//如果索引目錄被鎖定（比如索引過程中程序異常退出），則首先解鎖
if (IndexWriter.IsLocked(directory))
{
//解鎖索引庫
IndexWriter.Unlock(directory);
}
}
//創建IndexWriter對象，添加索引
IndexWriter writer = new IndexWriter(directory, new PanGuAnalyzer(), !isUpdate, Lucene.Net.Index.IndexWriter.MaxFieldLength.UNLIMITED);
//獲取新聞 title部分
string title = item.FileTitle;
//獲取新聞主內容
string body = item.FileContent;
//為避免重復索引，所以先刪除number=i的記錄，再重新添加
//尤其是更新的話，更是必須要先刪除之前的索引
writer.DeleteDocuments(new Term("id", item.FileName));
//創建索引文件 Document
Document document = new Document();
//只有對需要全文檢索的字段才ANALYZED
//添加id字段
document.Add(new Field("id", item.FileName, Field.Store.YES, Field.Index.NOT_ANALYZED));
//添加title字段
document.Add(new Field("title", title, Field.Store.YES, Field.Index.NOT_ANALYZED));
//添加body字段
document.Add(new Field("body", body, Field.Store.YES, Field.Index.ANALYZED, Lucene.Net.Documents.Field.TermVector.WITH_POSITIONS_OFFSETS));
//添加url字段
document.Add(new Field("url", item.FilePath, Field.Store.YES, Field.Index.NOT_ANALYZED));
//寫入索引庫
writer.AddDocument(document);
//關閉資源
writer.Close();
//不要忘了Close，否則索引結果搜不到
directory.Close();
//記錄日志
logger.Debug(String.Format("索引{0}創建成功",item.FileName));
}
catch (SystemException ex)
{
//記錄錯誤日志
logger.Error(ex);
throw;
}
catch (Exception ex)
{
//記錄錯誤日志
logger.Error(ex);
throw;
}
}
/// summary>
/// 根據id刪除相應索引
/// /summary>
/// param name="guid">要刪除的索引id/param>
public static void DeleteIndex(string guid)
{
try
{
////索引存儲庫
FSDirectory directory = FSDirectory.Open(new System.IO.DirectoryInfo(indexPath), new NativeFSLockFactory());
//判斷索引庫是否存在索引
bool isUpdate = IndexReader.IndexExists(directory);
if (isUpdate)
{
//如果索引目錄被鎖定（比如索引過程中程序異常退出），則首先解鎖
if (IndexWriter.IsLocked(directory))
{
IndexWriter.Unlock(directory);
}
}
IndexWriter writer = new IndexWriter(directory, new PanGuAnalyzer(), !isUpdate, Lucene.Net.Index.IndexWriter.MaxFieldLength.UNLIMITED);
//刪除索引文件
writer.DeleteDocuments(new Term("id", guid));
writer.Close();
directory.Close();//不要忘了Close，否則索引結果搜不到
logger.Debug(String.Format("刪除索引{0}成功", guid));
}
catch (Exception ex)
{
//記錄日志
logger.Error(ex);
//拋出異常
throw;
}
}
}
}
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.PanGu;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.Search;
using Lucene.Net.Store;
using Model.HelperModel;
using System;
using System.Collections.Generic;
namespace BLL
{
public static class SearchBLL
{
//一個類中可能會有多處輸出到日志，多處需要記錄日志，常將logger做成static 靜態變量
/// summary>
/// 日志助手
/// /summary>
static Common.LogHelper logger = new Common.LogHelper(typeof(SearchBLL));
/// summary>
/// 索引保存位置
/// /summary>
static string indexPath = Common.ConfigurationHelper.AppSettingMapPath("IndexPath");
/// summary>
/// 搜索
/// /summary>
/// param name="keywords">用戶搜索的關鍵詞/param>
/// returns>返回搜索的結果/returns>
public static ListSearchResult> Search(string keywords)
{
try
{
//索引存儲庫
FSDirectory directory = FSDirectory.Open(new System.IO.DirectoryInfo(indexPath), new NoLockFactory());
//創建IndexReader對象
IndexReader reader = IndexReader.Open(directory, true);
//創建IndexSearcher對象
IndexSearcher searcher = new IndexSearcher(reader);
//新建PhraseQuery 查詢對象
PhraseQuery query = new PhraseQuery();
//把用戶輸入的關鍵詞進行拆詞
foreach (string word in SplitWord(keywords))
{
//添加搜索關鍵詞
query.Add(new Term("body", word));
}
//設置分詞間距為100字之內
query.SetSlop(100);
TopScoreDocCollector collector = TopScoreDocCollector.create(1000, true);
//根據查詢條件查詢結果
searcher.Search(query, null, collector);
//搜索到的ScoreDoc結果
ScoreDoc[] docs = collector.TopDocs(0, collector.GetTotalHits()).scoreDocs;
//保存搜索結果的list
ListSearchResult> listResult = new ListSearchResult>();
for (int i = 0; i docs.Length; i++)
{
//取到文檔的編號（主鍵，這個是Lucene .net分配的）
//檢索結果中只有文檔的id，如果要取Document，則需要Doc再去取
//降低內容占用
int docId = docs[i].doc;
//根據id找Document
Document doc = searcher.Doc(docId);
string number = doc.Get("id");
string title = doc.Get("title");
string body = doc.Get("body");
string url = doc.Get("url");
//建立一個搜索結果對象
SearchResult result = new SearchResult();
result.Number = number;
result.Title = title;
result.BodyPreview = Preview(body, keywords);
result.Url = url;
//添加到結果列表
listResult.Add(result);
}
if (listResult.Count == 0)
{
return null;
}
else
{
return listResult;
}
}
catch (SystemException ex)
{
logger.Error(ex);
return null;
}
catch (Exception ex)
{
logger.Error(ex);
return null;
}
}
/// summary>
/// 獲取內容預覽
/// /summary>
/// param name="body">內容/param>
/// param name="keyword">關鍵詞/param>
/// returns>/returns>
private static string Preview(string body, string keyword)
{
//創建HTMLFormatter,參數為高亮單詞的前后綴
PanGu.HighLight.SimpleHTMLFormatter simpleHTMLFormatter = new PanGu.HighLight.SimpleHTMLFormatter("font color=\"red\">", "/font>");
//創建 Highlighter ，輸入HTMLFormatter 和 盤古分詞對象Semgent
PanGu.HighLight.Highlighter highlighter = new PanGu.HighLight.Highlighter(simpleHTMLFormatter, new PanGu.Segment());
//設置每個摘要段的字符數
highlighter.FragmentSize = 100;
//獲取最匹配的摘要段
string bodyPreview = highlighter.GetBestFragment(keyword, body);
return bodyPreview;
}
/// summary>
/// 盤古分詞，對用戶輸入的搜索關鍵詞進行分詞
/// /summary>
/// param name="str">用戶輸入的關鍵詞/param>
/// returns>分詞之后的結果組成的數組/returns>
private static string[] SplitWord(string str)
{
Liststring> list = new Liststring>();
Analyzer analyzer = new PanGuAnalyzer();
TokenStream tokenStream = analyzer.TokenStream("", new System.IO.StringReader(str));
Lucene.Net.Analysis.Token token = null;
while ((token = tokenStream.Next()) != null)
{
list.Add(token.TermText());
}
return list.ToArray();
}
}
}
