public static NamedList doHighlighting(DocList docs, Query query, SolrQueryRequest req, String[] defaultFields) throws IOException {
if (!isHighlightingEnabled(req))
return null;
SolrIndexSearcher searcher = req.getSearcher();
NamedList fragments = new SimpleOrderedMap();
String[] fieldNames = getHighlightFields(query, req, defaultFields);
Document[] readDocs = new Document[docs.size()];
{
// pre-fetch documents using the Searcher's doc cache
Set<String> fset = new HashSet<String>();
for(String f : fieldNames) { fset.add(f); }
// fetch unique key if one exists.
SchemaField keyField = req.getSearcher().getSchema().getUniqueKeyField();
if(null != keyField)
fset.add(keyField.getName());
searcher.readDocs(readDocs, docs, fset);
}
// Highlight each document
DocIterator iterator = docs.iterator();
for (int i = 0; i < docs.size(); i++) {
int docId = iterator.nextDoc();
Document doc = readDocs[i];
NamedList docSummaries = new SimpleOrderedMap();
for (String fieldName : fieldNames) {
fieldName = fieldName.trim();
String[] docTexts = doc.getValues(fieldName);
if (docTexts == null) continue;
// get highlighter, and number of fragments for this field
Highlighter highlighter = getHighlighter(query, fieldName, req);
int numFragments = getMaxSnippets(fieldName, req);
String[] summaries;
TextFragment[] frag;
if (docTexts.length == 1) {
// single-valued field
TokenStream tstream;
try {
// attempt term vectors
tstream = TokenSources.getTokenStream(searcher.getReader(), docId, fieldName);
}
catch (IllegalArgumentException e) {
// fall back to analyzer
tstream = new TokenOrderingFilter(searcher.getSchema().getAnalyzer().tokenStream(fieldName, new StringReader(docTexts[0])), 10);
}
frag = highlighter.getBestTextFragments(tstream, docTexts[0], false, numFragments);
}
else {
// multi-valued field
MultiValueTokenStream tstream;
tstream = new MultiValueTokenStream(fieldName, docTexts, searcher.getSchema().getAnalyzer(), true);
frag = highlighter.getBestTextFragments(tstream, tstream.asSingleValue(), false, numFragments);
}
// convert fragments back into text
// TODO: we can include score and position information in output as snippet attributes
if (frag.length > 0) {
ArrayList<String> fragTexts = new ArrayList<String>();
for (int j = 0; j < frag.length; j++) {
if ((frag[j] != null) && (frag[j].getScore() > 0)) {
fragTexts.add(frag[j].toString());
}
}
summaries = fragTexts.toArray(new String[0]);
if (summaries.length > 0)
docSummaries.add(fieldName, summaries);
}
}
String printId = searcher.getSchema().printableUniqueKey(doc);
fragments.add(printId == null ? null : printId, docSummaries);
}