Source Code Cross Referenced for HighlightingUtils.java in  » Search-Engine » apache-solr-1.2.0 » org » apache » solr » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Search Engine » apache solr 1.2.0 » org.apache.solr.util 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /**
002:         * Licensed to the Apache Software Foundation (ASF) under one or more
003:         * contributor license agreements.  See the NOTICE file distributed with
004:         * this work for additional information regarding copyright ownership.
005:         * The ASF licenses this file to You under the Apache License, Version 2.0
006:         * (the "License"); you may not use this file except in compliance with
007:         * the License.  You may obtain a copy of the License at
008:         *
009:         *     http://www.apache.org/licenses/LICENSE-2.0
010:         *
011:         * Unless required by applicable law or agreed to in writing, software
012:         * distributed under the License is distributed on an "AS IS" BASIS,
013:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014:         * See the License for the specific language governing permissions and
015:         * limitations under the License.
016:         */package org.apache.solr.util;
017:
018:        import java.io.IOException;
019:        import java.io.StringReader;
020:        import java.util.HashMap;
021:        import java.util.HashSet;
022:        import java.util.Map;
023:        import java.util.Set;
024:        import java.util.List;
025:        import java.util.LinkedList;
026:        import java.util.ArrayList;
027:        import java.util.ListIterator;
028:
029:        import org.apache.solr.request.*;
030:        import org.apache.solr.search.DocIterator;
031:        import org.apache.solr.search.DocList;
032:        import org.apache.solr.search.SolrIndexSearcher;
033:        import org.apache.solr.schema.SchemaField;
034:
035:        import org.apache.lucene.analysis.*;
036:        import org.apache.lucene.document.Document;
037:        import org.apache.lucene.search.Query;
038:        import org.apache.lucene.search.highlight.*;
039:
040:        /**
041:         * Collection of Utility and Factory methods for Highlighting.
042:         */
043:        public class HighlightingUtils {
044:            private static final String SIMPLE = "simple";
045:
046:            private static final String HIGHLIGHT = "hl";
047:            private static final String PREFIX = "hl.";
048:            private static final String FIELDS = PREFIX + "fl";
049:            private static final String SNIPPETS = PREFIX + "snippets";
050:            private static final String FRAGSIZE = PREFIX + "fragsize";
051:            private static final String FORMATTER = PREFIX + "formatter";
052:            private static final String SIMPLE_PRE = PREFIX + SIMPLE + ".pre";
053:            private static final String SIMPLE_POST = PREFIX + SIMPLE + ".post";
054:            private static final String FIELD_MATCH = PREFIX
055:                    + "requireFieldMatch";
056:
057:            private static SolrParams DEFAULTS = null;
058:            static {
059:                Map<String, String> map = new HashMap<String, String>();
060:                map.put(SNIPPETS, "1");
061:                map.put(FRAGSIZE, "100");
062:                map.put(FORMATTER, SIMPLE);
063:                map.put(SIMPLE_PRE, "<em>");
064:                map.put(SIMPLE_POST, "</em>");
065:
066:                DEFAULTS = new MapSolrParams(map);
067:            }
068:
069:            /** Combine request parameters with highlighting defaults. */
070:            private static SolrParams getParams(SolrQueryRequest request) {
071:                return new DefaultSolrParams(request.getParams(), DEFAULTS);
072:            }
073:
074:            /**
075:             * Check whether Highlighting is enabled for this request.
076:             * @param request The current SolrQueryRequest
077:             * @return <code>true</code> if highlighting enabled, <code>false</code> if not.
078:             */
079:            public static boolean isHighlightingEnabled(SolrQueryRequest request) {
080:                return getParams(request).getBool(HIGHLIGHT, false);
081:            }
082:
083:            /**
084:             * Return a Highlighter appropriate for this field.
085:             * @param query The current Query
086:             * @param fieldName The name of the field
087:             * @param request The current SolrQueryRequest
088:             */
089:            public static Highlighter getHighlighter(Query query,
090:                    String fieldName, SolrQueryRequest request) {
091:                Highlighter highlighter = new Highlighter(getFormatter(
092:                        fieldName, request), getQueryScorer(query, fieldName,
093:                        request));
094:                highlighter
095:                        .setTextFragmenter(getFragmenter(fieldName, request));
096:                return highlighter;
097:            }
098:
099:            /**
100:             * Return a QueryScorer suitable for this Query and field.
101:             * @param query The current query
102:             * @param fieldName The name of the field
103:             * @param request The SolrQueryRequest
104:             */
105:            public static QueryScorer getQueryScorer(Query query,
106:                    String fieldName, SolrQueryRequest request) {
107:                boolean reqFieldMatch = getParams(request).getFieldBool(
108:                        fieldName, FIELD_MATCH, false);
109:                if (reqFieldMatch) {
110:                    return new QueryScorer(query, request.getSearcher()
111:                            .getReader(), fieldName);
112:                } else {
113:                    return new QueryScorer(query);
114:                }
115:            }
116:
117:            /**
118:             * Return a String array of the fields to be highlighted.
119:             * Falls back to the programatic defaults, or the default search field if the list of fields
120:             * is not specified in either the handler configuration or the request.
121:             * @param query The current Query
122:             * @param request The current SolrQueryRequest
123:             * @param defaultFields Programmatic default highlight fields, used if nothing is specified in the handler config or the request.
124:             */
125:            public static String[] getHighlightFields(Query query,
126:                    SolrQueryRequest request, String[] defaultFields) {
127:                String fields[] = getParams(request).getParams(FIELDS);
128:
129:                // if no fields specified in the request, or the handler, fall back to programmatic default, or default search field.
130:                if (emptyArray(fields)) {
131:                    // use default search field if highlight fieldlist not specified.
132:                    if (emptyArray(defaultFields)) {
133:                        fields = new String[] { request.getSchema()
134:                                .getDefaultSearchFieldName() };
135:                    } else {
136:                        fields = defaultFields;
137:                    }
138:                } else if (fields.length == 1) {
139:                    // if there's a single request/handler value, it may be a space/comma separated list
140:                    fields = SolrPluginUtils.split(fields[0]);
141:                }
142:
143:                return fields;
144:            }
145:
146:            private static boolean emptyArray(String[] arr) {
147:                return (arr == null || arr.length == 0 || arr[0] == null || arr[0]
148:                        .trim().length() == 0);
149:            }
150:
151:            /**
152:             * Return the max number of snippets for this field. If this has not
153:             * been configured for this field, fall back to the configured default
154:             * or the solr default.
155:             * @param fieldName The name of the field
156:             * @param request The current SolrQueryRequest
157:             */
158:            public static int getMaxSnippets(String fieldName,
159:                    SolrQueryRequest request) {
160:                return Integer.parseInt(getParams(request).getFieldParam(
161:                        fieldName, SNIPPETS));
162:            }
163:
164:            /**
165:             * Return a formatter appropriate for this field. If a formatter
166:             * has not been configured for this field, fall back to the configured
167:             * default or the solr default (SimpleHTMLFormatter).
168:             * 
169:             * @param fieldName The name of the field
170:             * @param request The current SolrQueryRequest
171:             * @return An appropriate Formatter.
172:             */
173:            public static Formatter getFormatter(String fieldName,
174:                    SolrQueryRequest request) {
175:                SolrParams p = getParams(request);
176:
177:                // SimpleHTMLFormatter is the only supported Formatter at the moment
178:                return new SimpleHTMLFormatter(p.getFieldParam(fieldName,
179:                        SIMPLE_PRE), p.getFieldParam(fieldName, SIMPLE_POST));
180:            }
181:
182:            /**
183:             * Return a fragmenter appropriate for this field. If a fragmenter
184:             * has not been configured for this field, fall back to the configured
185:             * default or the solr default (GapFragmenter).
186:             * 
187:             * @param fieldName The name of the field
188:             * @param request The current SolrQueryRequest
189:             * @return An appropriate Fragmenter.
190:             */
191:            public static Fragmenter getFragmenter(String fieldName,
192:                    SolrQueryRequest request) {
193:                int fragsize = Integer.parseInt(getParams(request)
194:                        .getFieldParam(fieldName, FRAGSIZE));
195:                return (fragsize <= 0) ? new NullFragmenter()
196:                        : new GapFragmenter(fragsize);
197:            }
198:
199:            /**
200:             * Generates a list of Highlighted query fragments for each item in a list
201:             * of documents, or returns null if highlighting is disabled.
202:             *
203:             * @param docs query results
204:             * @param query the query
205:             * @param req the current request
206:             * @param defaultFields default list of fields to summarize
207:             *
208:             * @return NamedList containing a NamedList for each document, which in
209:             * turns contains sets (field, summary) pairs.
210:             */
211:            public static NamedList doHighlighting(DocList docs, Query query,
212:                    SolrQueryRequest req, String[] defaultFields)
213:                    throws IOException {
214:                if (!isHighlightingEnabled(req))
215:                    return null;
216:
217:                SolrIndexSearcher searcher = req.getSearcher();
218:                NamedList fragments = new SimpleOrderedMap();
219:                String[] fieldNames = getHighlightFields(query, req,
220:                        defaultFields);
221:                Document[] readDocs = new Document[docs.size()];
222:                {
223:                    // pre-fetch documents using the Searcher's doc cache
224:                    Set<String> fset = new HashSet<String>();
225:                    for (String f : fieldNames) {
226:                        fset.add(f);
227:                    }
228:                    // fetch unique key if one exists.
229:                    SchemaField keyField = req.getSearcher().getSchema()
230:                            .getUniqueKeyField();
231:                    if (null != keyField)
232:                        fset.add(keyField.getName());
233:                    searcher.readDocs(readDocs, docs, fset);
234:                }
235:
236:                // Highlight each document
237:                DocIterator iterator = docs.iterator();
238:                for (int i = 0; i < docs.size(); i++) {
239:                    int docId = iterator.nextDoc();
240:                    Document doc = readDocs[i];
241:                    NamedList docSummaries = new SimpleOrderedMap();
242:                    for (String fieldName : fieldNames) {
243:                        fieldName = fieldName.trim();
244:                        String[] docTexts = doc.getValues(fieldName);
245:                        if (docTexts == null)
246:                            continue;
247:
248:                        // get highlighter, and number of fragments for this field
249:                        Highlighter highlighter = getHighlighter(query,
250:                                fieldName, req);
251:                        int numFragments = getMaxSnippets(fieldName, req);
252:
253:                        String[] summaries;
254:                        TextFragment[] frag;
255:                        if (docTexts.length == 1) {
256:                            // single-valued field
257:                            TokenStream tstream;
258:                            try {
259:                                // attempt term vectors
260:                                tstream = TokenSources.getTokenStream(searcher
261:                                        .getReader(), docId, fieldName);
262:                            } catch (IllegalArgumentException e) {
263:                                // fall back to analyzer
264:                                tstream = new TokenOrderingFilter(searcher
265:                                        .getSchema().getAnalyzer().tokenStream(
266:                                                fieldName,
267:                                                new StringReader(docTexts[0])),
268:                                        10);
269:                            }
270:                            frag = highlighter.getBestTextFragments(tstream,
271:                                    docTexts[0], false, numFragments);
272:                        } else {
273:                            // multi-valued field
274:                            MultiValueTokenStream tstream;
275:                            tstream = new MultiValueTokenStream(fieldName,
276:                                    docTexts, searcher.getSchema()
277:                                            .getAnalyzer(), true);
278:                            frag = highlighter.getBestTextFragments(tstream,
279:                                    tstream.asSingleValue(), false,
280:                                    numFragments);
281:                        }
282:                        // convert fragments back into text
283:                        // TODO: we can include score and position information in output as snippet attributes
284:                        if (frag.length > 0) {
285:                            ArrayList<String> fragTexts = new ArrayList<String>();
286:                            for (int j = 0; j < frag.length; j++) {
287:                                if ((frag[j] != null)
288:                                        && (frag[j].getScore() > 0)) {
289:                                    fragTexts.add(frag[j].toString());
290:                                }
291:                            }
292:                            summaries = fragTexts.toArray(new String[0]);
293:                            if (summaries.length > 0)
294:                                docSummaries.add(fieldName, summaries);
295:                        }
296:                    }
297:                    String printId = searcher.getSchema().printableUniqueKey(
298:                            doc);
299:                    fragments.add(printId == null ? null : printId,
300:                            docSummaries);
301:                }
302:                return fragments;
303:            }
304:        }
305:
306:        /** 
307:         * Helper class which creates a single TokenStream out of values from a 
308:         * multi-valued field.
309:         */
310:        class MultiValueTokenStream extends TokenStream {
311:            private String fieldName;
312:            private String[] values;
313:            private Analyzer analyzer;
314:            private int curIndex; // next index into the values array
315:            private int curOffset; // offset into concatenated string
316:            private TokenStream currentStream; // tokenStream currently being iterated
317:            private boolean orderTokenOffsets;
318:
319:            /** Constructs a TokenStream for consecutively-analyzed field values
320:             *
321:             * @param fieldName name of the field
322:             * @param values array of field data
323:             * @param analyzer analyzer instance
324:             */
325:            public MultiValueTokenStream(String fieldName, String[] values,
326:                    Analyzer analyzer, boolean orderTokenOffsets) {
327:                this .fieldName = fieldName;
328:                this .values = values;
329:                this .analyzer = analyzer;
330:                curIndex = -1;
331:                curOffset = 0;
332:                currentStream = null;
333:                this .orderTokenOffsets = orderTokenOffsets;
334:            }
335:
336:            /** Returns the next token in the stream, or null at EOS. */
337:            public Token next() throws IOException {
338:                int extra = 0;
339:                if (currentStream == null) {
340:                    curIndex++;
341:                    if (curIndex < values.length) {
342:                        currentStream = analyzer.tokenStream(fieldName,
343:                                new StringReader(values[curIndex]));
344:                        if (orderTokenOffsets)
345:                            currentStream = new TokenOrderingFilter(
346:                                    currentStream, 10);
347:                        // add extra space between multiple values
348:                        if (curIndex > 0)
349:                            extra = analyzer.getPositionIncrementGap(fieldName);
350:                    } else {
351:                        return null;
352:                    }
353:                }
354:                Token nextToken = currentStream.next();
355:                if (nextToken == null) {
356:                    curOffset += values[curIndex].length();
357:                    currentStream = null;
358:                    return next();
359:                }
360:                // create an modified token which is the offset into the concatenated
361:                // string of all values
362:                Token offsetToken = new Token(nextToken.termText(), nextToken
363:                        .startOffset()
364:                        + curOffset, nextToken.endOffset() + curOffset);
365:                offsetToken.setPositionIncrement(nextToken
366:                        .getPositionIncrement()
367:                        + extra * 10);
368:                return offsetToken;
369:            }
370:
371:            /**
372:             * Returns all values as a single String into which the Tokens index with
373:             * their offsets.
374:             */
375:            public String asSingleValue() {
376:                StringBuilder sb = new StringBuilder();
377:                for (String str : values)
378:                    sb.append(str);
379:                return sb.toString();
380:            }
381:
382:        }
383:
384:        /**
385:         * A simple modification of SimpleFragmenter which additionally creates new
386:         * fragments when an unusually-large position increment is encountered
387:         * (this behaves much better in the presence of multi-valued fields).
388:         */
389:        class GapFragmenter extends SimpleFragmenter {
390:            /** 
391:             * When a gap in term positions is observed that is at least this big, treat
392:             * the gap as a fragment delimiter.
393:             */
394:            public static final int INCREMENT_THRESHOLD = 50;
395:            protected int fragOffsetAccum = 0;
396:
397:            public GapFragmenter() {
398:            }
399:
400:            public GapFragmenter(int fragsize) {
401:                super (fragsize);
402:            }
403:
404:            /* (non-Javadoc)
405:             * @see org.apache.lucene.search.highlight.TextFragmenter#start(java.lang.String)
406:             */
407:            public void start(String originalText) {
408:                fragOffsetAccum = 0;
409:            }
410:
411:            /* (non-Javadoc)
412:             * @see org.apache.lucene.search.highlight.TextFragmenter#isNewFragment(org.apache.lucene.analysis.Token)
413:             */
414:            public boolean isNewFragment(Token token) {
415:                boolean isNewFrag = token.endOffset() >= fragOffsetAccum
416:                        + getFragmentSize()
417:                        || token.getPositionIncrement() > INCREMENT_THRESHOLD;
418:                if (isNewFrag) {
419:                    fragOffsetAccum += token.endOffset() - fragOffsetAccum;
420:                }
421:                return isNewFrag;
422:            }
423:        }
424:
425:        /** Orders Tokens in a window first by their startOffset ascending.
426:         * endOffset is currently ignored.
427:         * This is meant to work around fickleness in the highlighter only.  It
428:         * can mess up token positions and should not be used for indexing or querying.
429:         */
430:        class TokenOrderingFilter extends TokenFilter {
431:            private final int windowSize;
432:            private final LinkedList<Token> queue = new LinkedList<Token>();
433:            private boolean done = false;
434:
435:            protected TokenOrderingFilter(TokenStream input, int windowSize) {
436:                super (input);
437:                this .windowSize = windowSize;
438:            }
439:
440:            public Token next() throws IOException {
441:                while (!done && queue.size() < windowSize) {
442:                    Token newTok = input.next();
443:                    if (newTok == null) {
444:                        done = true;
445:                        break;
446:                    }
447:
448:                    // reverse iterating for better efficiency since we know the
449:                    // list is already sorted, and most token start offsets will be too.
450:                    ListIterator<Token> iter = queue.listIterator(queue.size());
451:                    while (iter.hasPrevious()) {
452:                        if (newTok.startOffset() >= iter.previous()
453:                                .startOffset()) {
454:                            // insertion will be before what next() would return (what
455:                            // we just compared against), so move back one so the insertion
456:                            // will be after.
457:                            iter.next();
458:                            break;
459:                        }
460:                    }
461:                    iter.add(newTok);
462:                }
463:
464:                return queue.isEmpty() ? null : queue.removeFirst();
465:            }
466:        }
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