Hi,
I am not able to add synonyms to the lucene index.
I condensed my problem into the following class which is based on a Hello World
example.
The idea behind the code was to add a document with universität and the synonym
'Hochschule' (highschool)
so that lucene finds universität wenn I query Hochschule.
But it doesn't and I checked the index contents with a term iterator.
Hochschule is not added to the index:
package test;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.core.LowerCaseFilter;
import org.apache.lucene.analysis.standard.ClassicTokenizer;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.synonym.SynonymFilter;
import org.apache.lucene.analysis.synonym.SynonymMap;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.*;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.CharsRef;
import org.apache.lucene.util.Version;
import java.io.IOException;
import java.io.Reader;
public class LuceneHelloWorld {
public static void main(String[] args) throws Exception {
Analyzer analyzer = getAnalyzer();
Directory directory = new RAMDirectory();
IndexWriterConfig config = new IndexWriterConfig( Version.LUCENE_48,
analyzer);
IndexWriter writer = new IndexWriter(directory, config);
addDoc( writer, "people", "Hello Universität" );
addDoc( writer, "world", "Hello World" );
addDoc( writer, "people", "Hello people" );
writer.close();
IndexReader reader = DirectoryReader.open(directory);
IndexSearcher searcher = new IndexSearcher (reader);
QueryParser parser = new QueryParser ( Version.LUCENE_48, "content",
analyzer);
test( parser, searcher, "Hochschule");
test( parser, searcher, "Hello");
test( parser, searcher, "people");
test( parser, searcher, "universität");
printIndexTerms( reader);
}
public static void addDoc( IndexWriter writer, String title, String
content) throws Exception {
Document document = new Document ();
document.add(new TextField("title", title, Field.Store.YES));
document.add(new TextField("content", content, Field.Store.YES));
writer.addDocument(document);
}
public static Analyzer getAnalyzer(){
//return new StandardAnalyzer(Version.LUCENE_48);
//return new SynonymAnalyzer();
//return new SynonymFromStandardAnalyzer(Version.LUCENE_48);
return new Analyzer() {
@Override
protected TokenStreamComponents createComponents(String fieldName,
Reader reader) {
// TODO Auto-generated method stub
Tokenizer source = new ClassicTokenizer(Version.LUCENE_48,
reader);
TokenStream filter = new StandardFilter(Version.LUCENE_48,
source);
filter = new LowerCaseFilter(Version.LUCENE_48,filter);
SynonymMap mySynonymMap = null;
try {
//mySynonymMap = buildSynonym();
SynonymMap.Builder builder = new SynonymMap.Builder(true);
//loadSynonyms(builder);
builder.add(new CharsRef("Hochschule"), new
CharsRef("Universität"), true);
builder.add(new CharsRef("Universität"), new
CharsRef("Hochschule"), true);
mySynonymMap = builder.build();
} catch (IOException e) {
// TODO Auto-generated catch bl filter = new
SynonymFilter(filter, mySynonymMap, false);
return new TokenStreamComponents(source, filter);
}
};
}
static void test( QueryParser parser, IndexSearcher searcher, String
queryStr) throws Exception {
Query query = parser.parse(queryStr);
TopDocs results = searcher.search(query, 10);
System.out.println( "#Hits: " + results.totalHits + " : " + queryStr);
}
public static void printIndexTerms( IndexReader reader) throws Exception {
Terms terms = SlowCompositeReaderWrapper.wrap(reader).terms("content");
TermsEnum iterator =terms.iterator(TermsEnum.EMPTY);
BytesRef byteRef;
while ( (byteRef = iterator.next())!=null){
String term = byteRef.utf8ToString();
System.out.println(" term: " + term);
}
}
}
output:
#Hits: 0 : Hochschule
#Hits: 3 : Hello
#Hits: 1 : people
#Hits: 1 : universität
term: hello
term: pe
