龙空技术网

龙空技术网

使用Lucene.Net实现全文检索

opendotnet 744

前言：

现在各位老铁们对“lucene搜索引擎”都比较珍视，各位老铁们都想要学习一些“lucene搜索引擎”的相关文章。那么小编同时在网摘上汇集了一些有关“lucene搜索引擎””的相关文章，希望姐妹们能喜欢，兄弟们一起来学习一下吧！

Lucene.net是Lucene的.net移植版本，是一个开源的全文检索引擎开发包，即它不是一个完整的全文检索引擎，而是一个全文检索引擎的架构，提供了完整的查询引擎和索引引擎。

开发人员可以基于Lucene.net实现全文检索的功能。

Lucene.net是Apache软件基金会赞助的开源项目，基于Apache License协议。

Lucene.net并不是一个爬行搜索引擎，也不会自动地索引内容。我们得先将要索引的文档中的文本抽取出来，然后再将其加到Lucene.net索引中。标准的步骤是先初始化一个Analyzer、打开一个IndexWriter、然后再将文档一个接一个地加进去。一旦完成这些步骤，索引就可以在关闭前得到优化，同时所做的改变也会生效。这个过程可能比开发者习惯的方式更加手工化一些，但却在数据的索引上给予你更多的灵活性，而且其效率也很高。

获取索引目录

 /// <summary>
 /// 获取索引目录
 /// </summary>
 /// <param name="index">索引类型</param>
 /// <returns>索引目录</returns>
 private LcStore.Directory GetLuceneDirectory(IndexType index)
 {
 var indexPath = string.Empty;
 try
 {
 var dirPath = ConfigHelper.GetAppSetting("LuceneIndexPath");
 var indexName = Enum.EnumHelper.GetEnumDescription(index);
 indexPath = Path.Combine(dirPath, indexName);
return LcStore.FSDirectory.Open(indexPath);
 }
 catch (Exception ex)
 {
 NLogger.Write($"获取索引目录失败" + Environment.NewLine +
 $"路径：{indexPath}" + Environment.NewLine +
 $"异常信息：{ex}",
"Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("获取索引目录异常，详情请查看相关日志");
 }
 }
#endregion 获取目录
盘古分词
 /// <summary>
 /// 盘古分词
 /// </summary>
 /// <param name="keyword">语句</param>
 /// <returns>词组集合</returns>
 public string[] GetSplitKeywords(string keyword)
 {
 try
 {
 string ret = ;
 var reader = new StringReader(keyword);
 var ts = PanguAnalyzer.TokenStream(keyword, reader);
 var hasNext = ts.IncrementToken();
 Lucene.Net.Analysis.Tokenattributes.ITermAttribute ita;
while (hasNext)
 {
 ita = ts.GetAttribute<Lucene.Net.Analysis.Tokenattributes.ITermAttribute>();
 ret += ita.Term + "|";
 hasNext = ts.IncrementToken();
 }
 ts.CloneAttributes();
 reader.Close();
 PanguAnalyzer.Close();
if (string.IsOrWhiteSpace(ret)) return ;
 ret = ret.Substring(0, ret.Length - 1);
return ret.Split('|');
 }
 catch (Exception ex)
 {
 NLogger.Write("分词异常" + Environment.NewLine +
 $"关键词：{keyword}" + Environment.NewLine +
 $"异常信息：{ex}",
"Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("分词出现异常，详情请查看相关日志");
 }
 }
#endregion 分词
创建索引或追加索引
 /// <summary>
 /// 创建索引或追加索引
 /// </summary>
 /// <param name="dataList">数据集合</param>
 /// <param name="index">索引类型</param>
 public void CreateOrAppendIndexes(List<Document> dataList, IndexType index)
 {
if (dataList == || dataList.Count == 0)
return;
 IndexWriter writer;
 var directory = GetLuceneDirectory(index);
 try
 {
 //false表示追加（true表示删除之前的重新写入）
 writer = new IndexWriter(directory, PanguAnalyzer, false, IndexWriter.MaxFieldLength.LIMITED);
 }
 catch
 {
 //false表示追加（true表示删除之前的重新写入）
 writer = new IndexWriter(directory, PanguAnalyzer, true, IndexWriter.MaxFieldLength.LIMITED);
 }
 writer.MergeFactor = 1000;
 //writer.SetMaxBufferedDocs(1000);
 foreach (var doc in dataList)
 {
 writer.AddDocument(doc);
 }
 writer.Optimize();
 writer.Dispose();
 directory.Dispose();
 }
完整代码
 /// <summary>
 /// Lucene搜索引擎帮助类
 /// </summary>
 public class LuceneHelper
 {
 /// <summary>
 /// 私有构造函数
 /// </summary>
 private LuceneHelper()
 {
 }
#region 属性
 private static LuceneHelper _instance;
 /// <summary>
 /// 单一实例
 /// </summary>
 public static LuceneHelper Instance => _instance ?? (_instance = new LuceneHelper());
 private Analyzer _analyzer;
 /// <summary>
 /// 分析器
 /// </summary>
 private Analyzer PanguAnalyzer => _analyzer ?? (_analyzer = new PanGuAnalyzer());
#endregion 属性
#region 获取目录
 /// <summary>
 /// 获取索引目录
 /// </summary>
 /// <param name="index">索引类型</param>
 /// <returns>索引目录</returns>
 private LcStore.Directory GetLuceneDirectory(IndexType index)
 {
 var indexPath = string.Empty;
 try
 {
 var dirPath = ConfigHelper.GetAppSetting("LuceneIndexPath");
 var indexName = Enum.EnumHelper.GetEnumDescription(index);
 indexPath = Path.Combine(dirPath, indexName);
return LcStore.FSDirectory.Open(indexPath);
 }
 catch (Exception ex)
 {
 NLogger.Write($"获取索引目录失败" + Environment.NewLine +
 $"路径：{indexPath}" + Environment.NewLine +
 $"异常信息：{ex}",
"Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("获取索引目录异常，详情请查看相关日志");
 }
 }
#endregion 获取目录
#region 分词
 /// <summary>
 /// 盘古分词
 /// </summary>
 /// <param name="keyword">语句</param>
 /// <returns>词组集合</returns>
 public string[] GetSplitKeywords(string keyword)
 {
 try
 {
 string ret = ;
 var reader = new StringReader(keyword);
 var ts = PanguAnalyzer.TokenStream(keyword, reader);
 var hasNext = ts.IncrementToken();
 Lucene.Net.Analysis.Tokenattributes.ITermAttribute ita;
while (hasNext)
 {
 ita = ts.GetAttribute<Lucene.Net.Analysis.Tokenattributes.ITermAttribute>();
 ret += ita.Term + "|";
 hasNext = ts.IncrementToken();
 }
 ts.CloneAttributes();
 reader.Close();
 PanguAnalyzer.Close();
if (string.IsOrWhiteSpace(ret)) return ;
 ret = ret.Substring(0, ret.Length - 1);
return ret.Split('|');
 }
 catch (Exception ex)
 {
 NLogger.Write("分词异常" + Environment.NewLine +
 $"关键词：{keyword}" + Environment.NewLine +
 $"异常信息：{ex}",
"Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("分词出现异常，详情请查看相关日志");
 }
 }
#endregion 分词
#region 索引增删改查
 /// <summary>
 /// 创建索引或追加索引
 /// </summary>
 /// <param name="dataList">数据集合</param>
 /// <param name="index">索引类型</param>
 public void CreateOrAppendIndexes(List<Document> dataList, IndexType index)
 {
if (dataList == || dataList.Count == 0)
return;
 IndexWriter writer;
 var directory = GetLuceneDirectory(index);
 try
 {
 //false表示追加（true表示删除之前的重新写入）
 writer = new IndexWriter(directory, PanguAnalyzer, false, IndexWriter.MaxFieldLength.LIMITED);
 }
 catch
 {
 //false表示追加（true表示删除之前的重新写入）
 writer = new IndexWriter(directory, PanguAnalyzer, true, IndexWriter.MaxFieldLength.LIMITED);
 }
 writer.MergeFactor = 1000;
 //writer.SetMaxBufferedDocs(1000);
 foreach (var doc in dataList)
 {
 writer.AddDocument(doc);
 }
 writer.Optimize();
 writer.Dispose();
 directory.Dispose();
 }
 /// <summary>
 /// 删除索引
 /// </summary>
 /// <param name="field">字段名</param>
 /// <param name="value">字段值</param>
 /// <param name="index">索引类型</param>
 public void DeleteIndexes(string field, string value, IndexType index)
 {
 IndexWriter writer = ;
 var directory = GetLuceneDirectory(index);
 try
 {
 writer = new IndexWriter(directory, PanguAnalyzer, false, IndexWriter.MaxFieldLength.LIMITED);
 var term = new Term(field, value);
 writer.DeleteDocuments(term);
 //var isSuccess = writer.HasDeletions();
 writer.Optimize();
 }
 catch (Exception ex)
 {
 NLogger.Write("删除索引异常" + Environment.NewLine +
 $"异常信息：{ex}", "Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("删除索引异常，详情请查看相关日志");
 }
 finally
 {
 writer?.Dispose();
 directory?.Dispose();
 }
 }
 /// <summary>
 /// 更新索引；这里实际上是先删除原有索引，在创建新索引。
 /// 所以在更新索引时，一定要确保传入的Document的所有字段都有值
 /// 否则将会被置为空
 /// </summary>
 /// <param name="field">字段名</param>
 /// <param name="value">字段值</param>
 /// <param name="doc">文档</param>
 /// <param name="index">索引类型</param>
 public void UpdateIndexes(string field, string value, Document doc, IndexType index)
 {
 IndexWriter writer = ;
 var directory = GetLuceneDirectory(index);
 try
 {
 writer = new IndexWriter(directory, PanguAnalyzer, false, IndexWriter.MaxFieldLength.LIMITED);
 var term = new Term(field, value);
 writer.UpdateDocument(term, doc);
 }
 catch (Exception ex)
 {
 NLogger.Write("更新索引异常" + Environment.NewLine +
 $"异常信息：{ex}", "Lucene", "x", "x",
 CustomException.UnknownError, CustomLogLevel.Error);
 throw new Exception("更新索引异常，详情请查看相关日志");
 }
 finally
 {
 writer?.Dispose();
 directory?.Dispose();
 }
 }
#endregion 索引增删改查
#region 查询
 /// <summary>
 /// 查询
 /// </summary>
 /// <typeparam name="T">实体类型</typeparam>
 /// <param name="fields">条件字段</param>
 /// <param name="keywords">关键词组</param>
 /// <param name="index">索引类型</param>
 /// <param name="sort">排序，可为空</param>
 /// <param name="count">读取数量</param>
 /// <returns>结果集</returns>
 public List<T> Search<T>
 (
 string[] fields,
 string[] keywords,
 IndexType index,
 Sort sort,
 int count
 ) where T : new()
 {
if (fields == || fields.Length == 0)
return ;
if (keywords == || keywords.Length == 0)
return ;
 //索引目录
 var directory = GetLuceneDirectory(index);
 //查询条件
 var boolQuery = GetQuery(fields, keywords);
 //索引查询器
 var searcher = new IndexSearcher(directory, true);
 TopDocs docs;
if (sort != )
 docs = searcher.Search(boolQuery, , count, sort);
else
 docs = searcher.Search(boolQuery, count);
if (docs == || docs.TotalHits == 0)
return ;
 //文档集合
 var docList = docs.ScoreDocs.Select(sd => searcher.Doc(sd.Doc)).ToList();
 //反射赋值
 var list = ConvertDocToObj<T>(docList);
 searcher.Dispose();
 directory.Dispose();
return list;
 }
 /// <summary>
 /// 查询分页数据（指定排序方式）
 /// </summary>
 /// <typeparam name="T">实体类型</typeparam>
 /// <param name="fields">条件字段</param>
 /// <param name="keywords">关键词组</param>
 /// <param name="index">索引类型</param>
 /// <param name="sort">排序，必填</param>
 /// <param name="pageNumber">页码</param>
 /// <param name="pageSize">页数</param>
 /// <returns>结果集</returns>
 public PagedResult<List<T>> SearchByPaged<T>
 (
 string[] fields,
 string[] keywords,
 IndexType index,
 Sort sort,
 int pageNumber = 1,
 int pageSize = 20
 ) where T : new()
 {
if (fields == || fields.Length == 0)
return ;
if (keywords == || keywords.Length == 0)
return ;
 //索引目录
 var directory = GetLuceneDirectory(index);
 //查询条件
 var boolQuery = GetQuery(fields, keywords);
 var collector = TopFieldCollector
 .Create(sort, pageNumber * pageSize, false, false, false, false);
 var searcher = new IndexSearcher(directory, true);
 searcher.Search(boolQuery, collector);
if (collector == || collector.TotalHits == 0)
return ;
 //分页
 var start = (pageNumber - 1) * pageSize;
 var limit = pageSize;
 var hits = collector.TopDocs(start, limit).ScoreDocs;
 var totalCount = collector.TotalHits;
 var docList = hits.Select(sd => searcher.Doc(sd.Doc)).ToList();
 //反射赋值
 var list = ConvertDocToObj<T>(docList);
 searcher.Dispose();
 directory.Dispose();
return new PagedResult<List<T>>
 {
 Total = totalCount,
 Result = list
 };
 }
 /// <summary>
 /// 查询分页数据（默认排序方式）
 /// </summary>
 /// <typeparam name="T">实体类型</typeparam>
 /// <param name="fields">条件字段</param>
 /// <param name="keywords">关键词组</param>
 /// <param name="index">索引类型</param>
 /// <param name="pageNumber">页码</param>
 /// <param name="pageSize">页数</param>
 /// <returns>结果集</returns>
 public PagedResult<List<T>> SearchByPaged<T>
 (
 string[] fields,
 string[] keywords,
 IndexType index,
 int pageNumber = 1,
 int pageSize = 20
 ) where T : new()
 {
if (fields == || fields.Length == 0)
return ;
if (keywords == || keywords.Length == 0)
return ;
 //索引目录
 var directory = GetLuceneDirectory(index);
 //查询条件
 var boolQuery = GetQuery(fields, keywords);
 var collector = TopScoreDocCollector.Create(pageNumber * pageSize, false);
 var searcher = new IndexSearcher(directory, true);
 searcher.Search(boolQuery, collector);
if (collector == || collector.TotalHits == 0)
return ;
 //分页
 var start = (pageNumber - 1) * pageSize;
 var limit = pageSize;
 var hits = collector.TopDocs(start, limit).ScoreDocs;
 var totalCount = collector.TotalHits;
 var docList = hits.Select(sd => searcher.Doc(sd.Doc)).ToList();
 //反射赋值
 var list = ConvertDocToObj<T>(docList);
 searcher.Dispose();
 directory.Dispose();
return new PagedResult<List<T>>
 {
 Total = totalCount,
 Result = list
 };
 }
 /// <summary>
 /// 查询分页数据（默认排序方式）
 /// </summary>
 /// <param name="fields">条件字段</param>
 /// <param name="keywords">关键词组</param>
 /// <param name="index">索引类型</param>
 /// <returns>结果集</returns>
 public int GetTotla(string[] fields, string[] keywords, IndexType index)
 {
if (fields == || fields.Length == 0)
return 0;
if (keywords == || keywords.Length == 0)
return 0;
 //索引目录
 var directory = GetLuceneDirectory(index);
 //查询条件
 var boolQuery = GetQuery(fields, keywords);
 var collector = TopScoreDocCollector.Create(20, false);
 var searcher = new IndexSearcher(directory, true);
 searcher.Search(boolQuery, collector);
if (collector == || collector.TotalHits == 0)
return 0;
 searcher.Dispose();
 directory.Dispose();
return collector.TotalHits;
 }
 /// <summary>
 /// 文档转换为对象
 /// </summary>
 /// <typeparam name="T">实体类型</typeparam>
 /// <param name="docList">文档集合</param>
 /// <returns>对象集合</returns>
 private List<T> ConvertDocToObj<T>(List<Document> docList) where T : new()
 {
 var type = typeof(T);
 var propertyList = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
 var list = new List<T>();
 var firstDoc = docList.First();
 var fieldNames = firstDoc.GetFields().Select(x => x.Name).ToList();
 foreach (var doc in docList)
 {
 var tObj = new T();
 foreach (var pInfo in propertyList)
 {
 var name = pInfo.Name;
if (fieldNames.Any(x => x.ToLower() == name.ToLower()))
 {
 SetValue<T>(pInfo, tObj, doc, name);
 }
 }
 list.Add(tObj);
 }
return list;
 }
 /// <summary>
 /// 获取查询条件
 /// </summary>
 /// <param name="fields">条件字段</param>
 /// <param name="keywords">关键词组</param>
 /// <returns></returns>
 private BooleanQuery GetQuery(string[] fields, string[] keywords)
 {
 var boolQuery = new BooleanQuery();
 foreach (var field in fields)
 {
 foreach (var keyword in keywords)
 {
 var t = new TermQuery(new Term(field, keyword));
 boolQuery.Add(t, Occur.SHOULD);
 }
 }
return boolQuery;
 }
#endregion 查询
 private void SetValue<T>(PropertyInfo pInfo, T tObj, Document doc, string name)
 {
 var pType = pInfo.PropertyType.Name;
 switch (pType)
 {
case "String":
 pInfo.SetValue(tObj, doc.Get(name), );
break;
case "Int32":
 pInfo.SetValue(tObj, GetInt(doc.Get(name)), );
break;
case "Boolean":
 pInfo.SetValue(tObj, GetBool(doc.Get(name)), );
break;
case "DateTime":
 pInfo.SetValue(tObj, GetDate(doc.Get(name)), );
break;
case "Double":
 pInfo.SetValue(tObj, GetDouble(doc.Get(name)), );
break;
case "Single":
 pInfo.SetValue(tObj, GetFloat(doc.Get(name)), );
break;
case "Decimal":
 pInfo.SetValue(tObj, GetDecimal(doc.Get(name)), );
break;
 }
 }
 private int GetInt(string value)
 {
 var result = 0;
 int.TryParse(value, out result);
return result;
 }
 private DateTime GetDate(string value)
 {
 DateTime result;
 DateTime.TryParse(value, out result);
return result;
 }
 private bool GetBool(string value)
 {
 bool result;
 bool.TryParse(value, out result);
return result;
 }
 private double GetDouble(string value)
 {
 double result;
 double.TryParse(value, out result);
return result;
 }
 private float GetFloat(string value)
 {
float result;
 float.TryParse(value, out result);
return result;
 }
 private decimal GetDecimal(string value)
 {
 decimal result;
 decimal.TryParse(value, out result);
return result;
 }
 }

版权声明： 本站文章均来自互联网搜集，如有侵犯您的权益，请联系我们删除，谢谢。

标签： #lucene搜索引擎 #netlucene文件检索 #lucenenet检索文件

上一篇如何估计仿真的误差范围

下一篇哈夫曼编码的理解(Huffman Coding)

相关文章

    使用Lucene.Net实现全文检索

    使用Lucene.Net实现全文检索

    算法 opendotnet