private Searcher()
{
this.MongoDbServer = Constants.DefaultServerAddress;
this.DbName = Constants.DefaultDbName;
_segmentor = new ChineseSegmentor();
}
public Dictionary<Int32, Int32> Search(String keyword)
{
var server = MongoDbLib.GetServerConnection(ServerAddress);
var database = server.GetDatabase(DbName);
var tblWordList = database.GetCollection<WordItem>(Constants.TblWordList);
var tblFullText = database.GetCollection<InvertedIndex>(Constants.TblFullText);
// 針對搜尋關鍵字斷詞
ChineseSegmentor segmentor = new ChineseSegmentor();
List<Pair<String, Int32>> keywordTokens = segmentor.SegWords(keyword);
// 自索引中取出對應的 word list
var buf = (from t in keywordTokens select t.First).ToList();
var query = from w in tblWordList.AsQueryable<WordItem>()
where w.Word.In(buf)
select new { w.WordId };
List<Int32> wordIdList = new List<Int32>();
foreach (var aWord in query)
{
wordIdList.Add(aWord.WordId);
}
// 自全文索引中，取出對應的記錄
var indexes = from i in tblFullText.AsQueryable<InvertedIndex>()
where i.WordId.In(wordIdList)
select i;
if (indexes.Count() != wordIdList.Count)
{
return null;
}
// 將每個 keyword token 對應回相對應的 index
List<List<IndexElement>> checkedIndex = new List<List<IndexElement>>();
foreach (var aToken in keywordTokens)
{
checkedIndex.Add(indexes.Where(t => t.Word == aToken.First).First().Indexes);
}
// 檢查各文件是否為符合的文件
var firstTokenIndex = checkedIndex[0];
Dictionary<Int32, Int32> hittedDocs = new Dictionary<Int32, Int32>();
foreach (var currentIndex in firstTokenIndex)
{
if (keywordTokens.Count == 1 || CheckDocumentIsHitted(keywordTokens, 1, checkedIndex, currentIndex))
{
if (hittedDocs.ContainsKey(currentIndex.DocId))
hittedDocs[currentIndex.DocId]++;
else
hittedDocs[currentIndex.DocId] = 1;
}
}
// 將文件照點閱率排序
var sortedDict = (from entry in hittedDocs orderby entry.Value descending select entry).ToDictionary(pair => pair.Key, pair => pair.Value);
return sortedDict;
}
public bool MakeIndex()
{
try
{
// 1. 解文
Fetch();
// 2. 建索引
ChineseSegmentor segmentor = new ChineseSegmentor();
var server = MongoDbLib.GetServerConnection(ServerAddress);
var database = server.GetDatabase(DbName);
var tblSourceText = database.GetCollection<SourceDocument>(Constants.TblSourceText);
// 斷詞，處理每個 Token
var sourcees = from s in tblSourceText.AsQueryable<SourceDocument>()
orderby s.DocId, s.ParaId
select s;
Dictionary<String, InvertedIndex> fullIndexes = new Dictionary<String, InvertedIndex>();
InvertedIndex aIndex = null;
foreach (var aSourceText in sourcees)
{
List<Pair<String, Int32>> result = segmentor.SegWords(aSourceText.Para);
foreach (var aToken in result)
{
if (fullIndexes.ContainsKey(aToken.First))
{
aIndex = fullIndexes[aToken.First];
}
else
{
aIndex = new InvertedIndex();
aIndex.Word = aToken.First;
}
aIndex.Indexes.Add(new IndexElement()
{
DocId = aSourceText.DocId,
ParaId = aSourceText.ParaId,
Offset = aToken.Second
});
fullIndexes[aToken.First] = aIndex;
}
}
// 在 Storage 存入 Word List
var wordListCollection = database.GetCollection(Constants.TblWordList);
List<BsonDocument> batch = new List<BsonDocument>();
List<String> wordList = fullIndexes.Keys.ToList();
for (int wordId = 0; wordId < fullIndexes.Count; wordId++)
{
aIndex = fullIndexes[wordList[wordId]];
aIndex.WordId = wordId;
batch.Add(new BsonDocument()
{
{ "Word", wordList[wordId] },
{ "WordId", wordId}
});
}
wordListCollection.InsertBatch(batch);
// 儲存全文索引
var tblFullText = database.GetCollection(Constants.TblFullText);
List<InvertedIndex> fullText = new List<InvertedIndex>();
tblFullText.InsertBatch<InvertedIndex>(fullIndexes.Values.ToList());
return true;
}
catch (Exception e)
{
Console.WriteLine(e.StackTrace);
return false;
}
}