Here is what I am doing, not so magical... There are two classes, an
analyzer and an a TokenStream in which I can inject my document dependent
data to be stored as payload.
private PayloadAnalyzer panalyzer = new PayloadAnalyzer();
private class PayloadAnalyzer extends Analyzer {
private PayloadTokenStream payToken = null;
private int score;
public synchronized void setScore(int s) {
score=s;
}
public final TokenStream tokenStream(String field, Reader reader) {
payToken = new PayloadTokenStream(new LowerCaseTokenizer(reader));
payToken.setScore(score);
return payToken;
}
}
private class PayloadTokenStream extends TokenStream {
private Tokenizer tok = null;
private int score;
public PayloadTokenStream(Tokenizer tokenizer) {
tok = tokenizer;
}
public void setScore(int s) {
score = s;
}
public Token next(Token t) throws IOException {
t = tok.next(t);
if (t != null) {
//t.setTermBuffer("can change");
//Do something with the data
byte[] bytes = ("score:"+ score).getBytes();
t.setPayload(new Payload(bytes));
}
return t;
}
public void reset(Reader input) throws IOException {
tok.reset(input);
}
public void close() throws IOException {
tok.close();
}
}
public void doIndex() {
try {
File index = new File("./TestPayloadIndex");
IndexWriter iwriter = new IndexWriter(index,
panalyzer,
IndexWriter.MaxFieldLength.UNLIMITED);
Document d = new Document();
d.add(new Field("content",
"Everyone, someone, myTerm, yourTerm", Field.Store.YES,
Field.Index.ANALYZED, Field.TermVector.YES));
//We set the score for the term of the document that will be
analyzed.
/*I was worried about this part - document dependent score
which may be utilized*/
panalyzer.setScore(5);
iwriter.addDocument(d, panalyzer);
/*-----------------*/
...
iwriter.commit();
iwriter.optimize();
iwriter.close();
//Now read the index
IndexReader ireader = IndexReader.open(index);
TermPositions tpos = ireader.termPositions(
new Term("content","myterm"));//Note
LowercaseTokenizer
while (tpos.next()) {
int pos;
for(int i=0;i<tpos.freq();i++){
pos=tpos.nextPosition();
if (tpos.isPayloadAvailable()) {
byte[] data = new byte[tpos.getPayloadLength()];
tpos.getPayload(data, 0);
//Utilise payloads;
}
}
}
tpos.close();
} catch (CorruptIndexException ex) {
//
} catch (LockObtainFailedException ex) {
//
} catch (IOException ex) {
//
}
}
I wish it was designed better... Please let me know if you guys have a
better idea.
Cheers,
Murat
> Dear Murat,
>
> I saw your question and wondered how did you implement these changes?
> The requirement below are the same ones as I am trying to code now.
> Did you modify the source code itself or only used Lucene's jar and just
> override code?
>
> I would very much apprecicate if you could give me a short explanation on
> how was it done.
>
> Thanks a lot,
> Liat
>
> 2009/4/21 Murat Yakici <murat.yak...@cis.strath.ac.uk>
>
>> Hi,
>> I started playing with the experimental payload functionality. I have
>> written an analyzer which adds a payload (some sort of a score/boost)
>> for
>> each term occurance. The payload/score for each term is dependent on the
>> document that the term comes from (I guess this is the typoical use
>> case).
>> So say term t1 may have a payload of 5 in doc1 and 34 in doc5. The
>> parameter
>> for calculating the payload changes after each
>> indexWriter.addDocument(..)
>> method call in a while loop. I am assuming that the
>> indexWriter.addDocument(..) methods are thread safe. Can I confirm this?
>>
>> Cheers,
>>
>> --
>> Murat Yakici
>> Department of Computer & Information Sciences
>> University of Strathclyde
>> Glasgow, UK
>> -------------------------------------------
>> The University of Strathclyde is a charitable body, registered in
>> Scotland,
>> with registration number SC015263.
>>
>>
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>>
>>
>
Murat Yakici
Department of Computer & Information Sciences
University of Strathclyde
Glasgow, UK
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