Java tutorial
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See the License for the * specific language governing permissions and limitations * under the License. */ package org.elasticsearch.search.fetch.subphase.highlight; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.highlight.Encoder; import org.apache.lucene.search.highlight.Snippet; import org.apache.lucene.search.uhighlight.CustomPassageFormatter; import org.apache.lucene.search.uhighlight.CustomUnifiedHighlighter; import org.apache.lucene.util.BytesRef; import org.apache.lucene.util.CollectionUtil; import org.elasticsearch.common.Strings; import org.elasticsearch.common.text.Text; import org.elasticsearch.index.mapper.FieldMapper; import org.elasticsearch.search.fetch.FetchPhaseExecutionException; import org.elasticsearch.search.fetch.FetchSubPhase; import org.elasticsearch.search.internal.SearchContext; import java.io.IOException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.stream.Collectors; import static org.elasticsearch.search.fetch.subphase.highlight.PostingsHighlighter.filterSnippets; import static org.elasticsearch.search.fetch.subphase.highlight.PostingsHighlighter.mergeFieldValues; public class UnifiedHighlighter implements Highlighter { private static final String CACHE_KEY = "highlight-unified"; @Override public boolean canHighlight(FieldMapper fieldMapper) { return true; } @Override public HighlightField highlight(HighlighterContext highlighterContext) { FieldMapper fieldMapper = highlighterContext.mapper; SearchContextHighlight.Field field = highlighterContext.field; SearchContext context = highlighterContext.context; FetchSubPhase.HitContext hitContext = highlighterContext.hitContext; if (!hitContext.cache().containsKey(CACHE_KEY)) { hitContext.cache().put(CACHE_KEY, new HighlighterEntry()); } HighlighterEntry highlighterEntry = (HighlighterEntry) hitContext.cache().get(CACHE_KEY); MapperHighlighterEntry mapperHighlighterEntry = highlighterEntry.mappers.get(fieldMapper); if (mapperHighlighterEntry == null) { Encoder encoder = field.fieldOptions().encoder().equals("html") ? HighlightUtils.Encoders.HTML : HighlightUtils.Encoders.DEFAULT; CustomPassageFormatter passageFormatter = new CustomPassageFormatter(field.fieldOptions().preTags()[0], field.fieldOptions().postTags()[0], encoder); mapperHighlighterEntry = new MapperHighlighterEntry(passageFormatter); } List<Snippet> snippets = new ArrayList<>(); int numberOfFragments; try { Analyzer analyzer = context.mapperService().documentMapper(hitContext.hit().getType()).mappers() .indexAnalyzer(); List<Object> fieldValues = HighlightUtils.loadFieldValues(field, fieldMapper, context, hitContext); fieldValues = fieldValues.stream().map(obj -> { if (obj instanceof BytesRef) { return fieldMapper.fieldType().valueForDisplay(obj).toString(); } else { return obj; } }).collect(Collectors.toList()); IndexSearcher searcher = new IndexSearcher(hitContext.reader()); CustomUnifiedHighlighter highlighter; if (field.fieldOptions().numberOfFragments() == 0) { // we use a control char to separate values, which is the only char that the custom break iterator // breaks the text on, so we don't lose the distinction between the different values of a field and we // get back a snippet per value String fieldValue = mergeFieldValues(fieldValues, HighlightUtils.NULL_SEPARATOR); org.apache.lucene.search.postingshighlight.CustomSeparatorBreakIterator breakIterator = new org.apache.lucene.search.postingshighlight.CustomSeparatorBreakIterator( HighlightUtils.NULL_SEPARATOR); highlighter = new CustomUnifiedHighlighter(searcher, analyzer, mapperHighlighterEntry.passageFormatter, breakIterator, fieldValue, field.fieldOptions().noMatchSize() > 0); numberOfFragments = fieldValues.size(); // we are highlighting the whole content, one snippet per value } else { //using paragraph separator we make sure that each field value holds a discrete passage for highlighting String fieldValue = mergeFieldValues(fieldValues, HighlightUtils.PARAGRAPH_SEPARATOR); highlighter = new CustomUnifiedHighlighter(searcher, analyzer, mapperHighlighterEntry.passageFormatter, null, fieldValue, field.fieldOptions().noMatchSize() > 0); numberOfFragments = field.fieldOptions().numberOfFragments(); } if (field.fieldOptions().requireFieldMatch()) { final String fieldName = highlighterContext.fieldName; highlighter.setFieldMatcher((name) -> fieldName.equals(name)); } else { highlighter.setFieldMatcher((name) -> true); } Snippet[] fieldSnippets = highlighter.highlightField(highlighterContext.fieldName, highlighterContext.query, hitContext.docId(), numberOfFragments); for (Snippet fieldSnippet : fieldSnippets) { if (Strings.hasText(fieldSnippet.getText())) { snippets.add(fieldSnippet); } } } catch (IOException e) { throw new FetchPhaseExecutionException(context, "Failed to highlight field [" + highlighterContext.fieldName + "]", e); } snippets = filterSnippets(snippets, field.fieldOptions().numberOfFragments()); if (field.fieldOptions().scoreOrdered()) { //let's sort the snippets by score if needed CollectionUtil.introSort(snippets, (o1, o2) -> Double.compare(o2.getScore(), o1.getScore())); } String[] fragments = new String[snippets.size()]; for (int i = 0; i < fragments.length; i++) { fragments[i] = snippets.get(i).getText(); } if (fragments.length > 0) { return new HighlightField(highlighterContext.fieldName, Text.convertFromStringArray(fragments)); } return null; } static class HighlighterEntry { Map<FieldMapper, MapperHighlighterEntry> mappers = new HashMap<>(); } static class MapperHighlighterEntry { final CustomPassageFormatter passageFormatter; private MapperHighlighterEntry(CustomPassageFormatter passageFormatter) { this.passageFormatter = passageFormatter; } } }