Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.jackrabbit.oak.plugins.index.lucene.util; import java.io.File; import java.io.IOException; import java.io.Reader; import java.util.Collections; import java.util.List; import com.google.common.io.Files; import org.apache.commons.io.FileUtils; import org.apache.jackrabbit.oak.plugins.index.lucene.FieldNames; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.index.IndexReader; import org.apache.lucene.search.spell.Dictionary; import org.apache.lucene.search.spell.LuceneDictionary; import org.apache.lucene.search.suggest.Lookup; import org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester; import org.apache.lucene.store.Directory; import org.apache.lucene.store.FSDirectory; import org.apache.lucene.util.Version; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Helper class for getting suggest results for a given term, calling a {@link org.apache.lucene.search.suggest.Lookup} * implementation under the hood. */ public class SuggestHelper { private static final Logger log = LoggerFactory.getLogger(SuggestHelper.class); private static final Analyzer analyzer = new Analyzer() { @Override protected Analyzer.TokenStreamComponents createComponents(String fieldName, Reader reader) { return new Analyzer.TokenStreamComponents(new CRTokenizer(Version.LUCENE_47, reader)); } }; public static void updateSuggester(Directory directory, Analyzer analyzer, IndexReader reader) throws IOException { File tempDir = null; try { //Analyzing infix suggester takes a file parameter. It uses its path to getDirectory() //for actual storage of suggester data. BUT, while building it also does getDirectory() to //a temporary location (original path + ".tmp"). So, instead we create a temp dir and also //create a placeholder non-existing-sub-child which would mark the location when we want to return //our internal suggestion OakDirectory. After build is done, we'd delete the temp directory //thereby removing any temp stuff that suggester created in the interim. tempDir = Files.createTempDir(); File tempSubChild = new File(tempDir, "non-existing-sub-child"); if (reader.getDocCount(FieldNames.SUGGEST) > 0) { Dictionary dictionary = new LuceneDictionary(reader, FieldNames.SUGGEST); getLookup(directory, analyzer, tempSubChild).build(dictionary); } } catch (RuntimeException e) { log.debug("could not update the suggester", e); } finally { //cleanup temp dir if (tempDir != null && !FileUtils.deleteQuietly(tempDir)) { log.error("Cleanup failed for temp dir {}", tempDir.getAbsolutePath()); } } } public static List<Lookup.LookupResult> getSuggestions(AnalyzingInfixSuggester suggester, SuggestQuery suggestQuery) { try { long count = suggester.getCount(); if (count > 0) { return suggester.lookup(suggestQuery.getText(), 10, true, false); } else { return Collections.emptyList(); } } catch (Exception e) { throw new RuntimeException("could not handle Suggest query " + suggestQuery, e); } } public static SuggestQuery getSuggestQuery(String suggestQueryString) { try { String text = null; for (String param : suggestQueryString.split("&")) { String[] keyValuePair = param.split("="); if (keyValuePair.length != 2 || keyValuePair[0] == null || keyValuePair[1] == null) { throw new RuntimeException("Unparsable native Lucene Suggest query: " + suggestQueryString); } else { if ("term".equals(keyValuePair[0])) { text = keyValuePair[1]; } } } if (text != null) { return new SuggestQuery(text); } else { return null; } } catch (Exception e) { throw new RuntimeException("could not build SuggestQuery " + suggestQueryString, e); } } public static AnalyzingInfixSuggester getLookup(final Directory suggestDirectory) throws IOException { return getLookup(suggestDirectory, SuggestHelper.analyzer); } public static AnalyzingInfixSuggester getLookup(final Directory suggestDirectory, Analyzer analyzer) throws IOException { return getLookup(suggestDirectory, analyzer, null); } public static AnalyzingInfixSuggester getLookup(final Directory suggestDirectory, Analyzer analyzer, final File tempDir) throws IOException { return new AnalyzingInfixSuggester(Version.LUCENE_47, tempDir, analyzer, analyzer, 3) { @Override protected Directory getDirectory(File path) throws IOException { if (tempDir == null || tempDir.getAbsolutePath().equals(path.getAbsolutePath())) { return suggestDirectory; // use oak directory for writing suggest index } else { return FSDirectory.open(path); // use FS for temp index used at build time } } }; } public static Analyzer getAnalyzer() { return analyzer; } public static class SuggestQuery { private final String text; public SuggestQuery(String text) { this.text = text; } public String getText() { return text; } @Override public String toString() { return "SuggestQuery{" + "text='" + text + '\'' + '}'; } } }