import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.ISOLatin1AccentFilter;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter.Side;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.spell.LuceneDictionary;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
/**
* Search term auto-completer, works for single terms (so use on the last term
* of the query).
*
* Returns more popular terms first.
*
* @author Mat Mannion, M.Mannion@warwick.ac.uk
*/
public final class Autocompleter {
private static final String GRAMMED_WORDS_FIELD = "words";
private static final String SOURCE_WORD_FIELD = "sourceWord";
private static final String COUNT_FIELD = "count";
private static final String[] ENGLISH_STOP_WORDS = {
"a", "an", "and", "are", "as", "at", "be", "but", "by",
"for", "i", "if", "in", "into", "is",
"no", "not", "of", "on", "or", "s", "such",
"t", "that", "the", "their", "then", "there", "these",
"they", "this", "to", "was", "will", "with"
};
private final Directory autoCompleteDirectory;
private IndexReader autoCompleteReader;
private IndexSearcher autoCompleteSearcher;
public Autocompleter(String autoCompleteDir) throws IOException {
this.autoCompleteDirectory = FSDirectory.getDirectory(autoCompleteDir,
null);
reOpenReader();
}
public List suggestTermsFor(String term) throws IOException {
// get the top 5 terms for query
Query query = new TermQuery(new Term(GRAMMED_WORDS_FIELD, term));
Sort sort = new Sort(COUNT_FIELD, true);
TopDocs docs = autoCompleteSearcher.search(query, null, 5, sort);
List suggestions = new ArrayList();
for (ScoreDoc doc : docs.scoreDocs) {
suggestions.add(autoCompleteReader.document(doc.doc).get(
SOURCE_WORD_FIELD));
}
return suggestions;
}
@SuppressWarnings("unchecked")
public void reIndex(Directory sourceDirectory, String fieldToAutocomplete)
throws CorruptIndexException, IOException {
// build a dictionary (from the spell package)
IndexReader sourceReader = IndexReader.open(sourceDirectory);
LuceneDictionary dict = new LuceneDictionary(sourceReader,
fieldToAutocomplete);
// code from
// org.apache.lucene.search.spell.SpellChecker.indexDictionary(
// Dictionary)
IndexReader.unlock(autoCompleteDirectory);
// use a custom analyzer so we can do EdgeNGramFiltering
IndexWriter writer = new IndexWriter(autoCompleteDirectory,
new Analyzer() {
public TokenStream tokenStream(String fieldName,
Reader reader) {
TokenStream result = new StandardTokenizer(reader);
result = new StandardFilter(result);
result = new LowerCaseFilter(result);
result = new ISOLatin1AccentFilter(result);
result = new StopFilter(result,
ENGLISH_STOP_WORDS);
result = new EdgeNGramTokenFilter(
result, Side.FRONT,1, 20);
return result;
}
}, true);
writer.setMergeFactor(300);
writer.setMaxBufferedDocs(150);
// go through every word, storing the original word (incl. n-grams)
// and the number of times it occurs
Map wordsMap = new HashMap();
Iterator iter = (Iterator) dict.getWordsIterator();
while (iter.hasNext()) {
String word = iter.next();
int len = word.length();
if (len < 3) {
continue; // too short we bail but "too long" is fine...
}
if (wordsMap.containsKey(word)) {
throw new IllegalStateException(
"This should never happen in Lucene 2.3.2");
// wordsMap.put(word, wordsMap.get(word) + 1);
} else {
// use the number of documents this word appears in
wordsMap.put(word, sourceReader.docFreq(new Term(
fieldToAutocomplete, word)));
}
}
for (String word : wordsMap.keySet()) {
// ok index the word
Document doc = new Document();
doc.add(new Field(SOURCE_WORD_FIELD, word, Field.Store.YES,
Field.Index.UN_TOKENIZED)); // orig term
doc.add(new Field(GRAMMED_WORDS_FIELD, word, Field.Store.YES,
Field.Index.TOKENIZED)); // grammed
doc.add(new Field(COUNT_FIELD,
Integer.toString(wordsMap.get(word)), Field.Store.NO,
Field.Index.UN_TOKENIZED)); // count
writer.addDocument(doc);
}
sourceReader.close();
// close writer
writer.optimize();
writer.close();
// re-open our reader
reOpenReader();
}
private void reOpenReader() throws CorruptIndexException, IOException {
if (autoCompleteReader == null) {
autoCompleteReader = IndexReader.open(autoCompleteDirectory);
} else {
autoCompleteReader.reopen();
}
autoCompleteSearcher = new IndexSearcher(autoCompleteReader);
}
public static void main(String[] args) throws Exception {
Autocompleter autocomplete = new Autocompleter("/index/autocomplete");
// run this to re-index from the current index, shouldn't need to do
// this very often
// autocomplete.reIndex(FSDirectory.getDirectory("/index/live", null),
// "content");
String term = "steve";
System.out.println(autocomplete.suggestTermsFor(term));
// prints [steve, steven, stevens, stevenson, stevenage]
}
}
// don't navigate away from the field when pressing tab on a selected item
$( "#search-input" ).keydown(function (event) {
if (event.keyCode === $.ui.keyCode.TAB && $(this).data("autocomplete").menu.active) {
event.preventDefault();
}
});
$( "#search-input" ).autocomplete({
source: '@Url.Action("SuggestTerms")', // <-- ASP.NET MVC Razor syntax
minLength: 2,
delay: 500,
focus: function () {
// prevent value inserted on focus
return false;
},
select: function (event, ui) {
var terms = this.value.split(/\s+/);
terms.pop(); // remove dropdown item
terms.push(ui.item.value.trim()); // add completed item
this.value = terms.join(" ");
return false;
},
});
...这是ASP.NET MVC控制器代码:
//
// GET: /MyApp/SuggestTerms?term=something
public JsonResult SuggestTerms(string term)
{
if (string.IsNullOrWhiteSpace(term))
return Json(new string[] {});
term = term.Split().Last();
// Fetch suggestions
string[] suggestions = SearchSvc.SuggestTermsFor(term).ToArray();
return Json(suggestions, JsonRequestBehavior.AllowGet);
}
...这里是C#中Mat的代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Lucene.Net.Store;
using Lucene.Net.Index;
using Lucene.Net.Search;
using SpellChecker.Net.Search.Spell;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Analysis.NGram;
using Lucene.Net.Documents;
namespace Cipher.Services
{
///
/// Search term auto-completer, works for single terms (so use on the last term of the query).
/// Returns more popular terms first.
///
/// Author: Mat Mannion, M.Mannion@warwick.ac.uk
///
///
///
public class SearchAutoComplete {
public int MaxResults { get; set; }
private class AutoCompleteAnalyzer : Analyzer
{
public override TokenStream TokenStream(string fieldName, System.IO.TextReader reader)
{
TokenStream result = new StandardTokenizer(kLuceneVersion, reader);
result = new StandardFilter(result);
result = new LowerCaseFilter(result);
result = new ASCIIFoldingFilter(result);
result = new StopFilter(false, result, StopFilter.MakeStopSet(kEnglishStopWords));
result = new EdgeNGramTokenFilter(
result, Lucene.Net.Analysis.NGram.EdgeNGramTokenFilter.DEFAULT_SIDE,1, 20);
return result;
}
}
private static readonly Lucene.Net.Util.Version kLuceneVersion = Lucene.Net.Util.Version.LUCENE_29;
private static readonly String kGrammedWordsField = "words";
private static readonly String kSourceWordField = "sourceWord";
private static readonly String kCountField = "count";
private static readonly String[] kEnglishStopWords = {
"a", "an", "and", "are", "as", "at", "be", "but", "by",
"for", "i", "if", "in", "into", "is",
"no", "not", "of", "on", "or", "s", "such",
"t", "that", "the", "their", "then", "there", "these",
"they", "this", "to", "was", "will", "with"
};
private readonly Directory m_directory;
private IndexReader m_reader;
private IndexSearcher m_searcher;
public SearchAutoComplete(string autoCompleteDir) :
this(FSDirectory.Open(new System.IO.DirectoryInfo(autoCompleteDir)))
{
}
public SearchAutoComplete(Directory autoCompleteDir, int maxResults = 8)
{
this.m_directory = autoCompleteDir;
MaxResults = maxResults;
ReplaceSearcher();
}
///
/// Find terms matching the given partial word that appear in the highest number of documents.
/// A word or part of a word
/// A list of suggested completions
public IEnumerable SuggestTermsFor(string term)
{
if (m_searcher == null)
return new string[] { };
// get the top terms for query
Query query = new TermQuery(new Term(kGrammedWordsField, term.ToLower()));
Sort sort = new Sort(new SortField(kCountField, SortField.INT));
TopDocs docs = m_searcher.Search(query, null, MaxResults, sort);
string[] suggestions = docs.ScoreDocs.Select(doc =>
m_reader.Document(doc.Doc).Get(kSourceWordField)).ToArray();
return suggestions;
}
///
/// Open the index in the given directory and create a new index of word frequency for the
/// given index.
/// Directory containing the index to count words in.
/// The field in the index that should be analyzed.
public void BuildAutoCompleteIndex(Directory sourceDirectory, String fieldToAutocomplete)
{
// build a dictionary (from the spell package)
using (IndexReader sourceReader = IndexReader.Open(sourceDirectory, true))
{
LuceneDictionary dict = new LuceneDictionary(sourceReader, fieldToAutocomplete);
// code from
// org.apache.lucene.search.spell.SpellChecker.indexDictionary(
// Dictionary)
//IndexWriter.Unlock(m_directory);
// use a custom analyzer so we can do EdgeNGramFiltering
var analyzer = new AutoCompleteAnalyzer();
using (var writer = new IndexWriter(m_directory, analyzer, true, IndexWriter.MaxFieldLength.LIMITED))
{
writer.MergeFactor = 300;
writer.SetMaxBufferedDocs(150);
// go through every word, storing the original word (incl. n-grams)
// and the number of times it occurs
foreach (string word in dict)
{
if (word.Length < 3)
continue; // too short we bail but "too long" is fine...
// ok index the word
// use the number of documents this word appears in
int freq = sourceReader.DocFreq(new Term(fieldToAutocomplete, word));
var doc = MakeDocument(fieldToAutocomplete, word, freq);
writer.AddDocument(doc);
}
writer.Optimize();
}
}
// re-open our reader
ReplaceSearcher();
}
private static Document MakeDocument(String fieldToAutocomplete, string word, int frequency)
{
var doc = new Document();
doc.Add(new Field(kSourceWordField, word, Field.Store.YES,
Field.Index.NOT_ANALYZED)); // orig term
doc.Add(new Field(kGrammedWordsField, word, Field.Store.YES,
Field.Index.ANALYZED)); // grammed
doc.Add(new Field(kCountField,
frequency.ToString(), Field.Store.NO,
Field.Index.NOT_ANALYZED)); // count
return doc;
}
private void ReplaceSearcher()
{
if (IndexReader.IndexExists(m_directory))
{
if (m_reader == null)
m_reader = IndexReader.Open(m_directory, true);
else
m_reader.Reopen();
m_searcher = new IndexSearcher(m_reader);
}
else
{
m_searcher = null;
}
}
}
}
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