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 com.zghw.lucene.demo; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.nio.charset.StandardCharsets; import java.util.Enumeration; import java.util.Properties; import java.util.StringTokenizer; import javax.servlet.RequestDispatcher; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.document.Field; import org.apache.lucene.document.FieldType; import org.apache.lucene.document.TextField; import org.apache.lucene.index.DirectoryReader; import org.apache.lucene.index.IndexReader; import org.apache.lucene.index.IndexWriter; import org.apache.lucene.index.IndexWriterConfig; import org.apache.lucene.queryparser.xml.CorePlusExtensionsParser; import org.apache.lucene.queryparser.xml.QueryTemplateManager; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.ScoreDoc; import org.apache.lucene.search.TopDocs; import org.apache.lucene.store.RAMDirectory; import org.apache.lucene.util.Version; /** * Example servlet that uses the XML queryparser. * <p> * NOTE: you must provide CSV data in <code>/WEB-INF/data.tsv</code> * for the demo to work! */ public class FormBasedXmlQueryDemo extends HttpServlet { private QueryTemplateManager queryTemplateManager; private CorePlusExtensionsParser xmlParser; private IndexSearcher searcher; private Analyzer analyzer = new StandardAnalyzer(); /** for instantiation by the servlet container */ public FormBasedXmlQueryDemo() { } @Override public void init(ServletConfig config) throws ServletException { super.init(config); try { openExampleIndex(); //load servlet configuration settings String xslFile = config.getInitParameter("xslFile"); String defaultStandardQueryParserField = config.getInitParameter("defaultStandardQueryParserField"); //Load and cache choice of XSL query template using QueryTemplateManager queryTemplateManager = new QueryTemplateManager( getServletContext().getResourceAsStream("/WEB-INF/" + xslFile)); //initialize an XML Query Parser for use by all threads xmlParser = new CorePlusExtensionsParser(defaultStandardQueryParserField, analyzer); } catch (Exception e) { throw new ServletException("Error loading query template", e); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //Take all completed form fields and add to a Properties object Properties completedFormFields = new Properties(); Enumeration<?> pNames = request.getParameterNames(); while (pNames.hasMoreElements()) { String propName = (String) pNames.nextElement(); String value = request.getParameter(propName); if ((value != null) && (value.trim().length() > 0)) { completedFormFields.setProperty(propName, value); } } try { //Create an XML query by populating template with given user criteria org.w3c.dom.Document xmlQuery = queryTemplateManager.getQueryAsDOM(completedFormFields); //Parse the XML to produce a Lucene query Query query = xmlParser.getQuery(xmlQuery.getDocumentElement()); //Run the query TopDocs topDocs = searcher.search(query, 10); //and package the results and forward to JSP if (topDocs != null) { ScoreDoc[] sd = topDocs.scoreDocs; Document[] results = new Document[sd.length]; for (int i = 0; i < results.length; i++) { results[i] = searcher.doc(sd[i].doc); request.setAttribute("results", results); } } RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/index.jsp"); dispatcher.forward(request, response); } catch (Exception e) { throw new ServletException("Error processing query", e); } } private void openExampleIndex() throws IOException { //Create a RAM-based index from our test data file RAMDirectory rd = new RAMDirectory(); IndexWriterConfig iwConfig = new IndexWriterConfig(Version.LUCENE_CURRENT, analyzer); IndexWriter writer = new IndexWriter(rd, iwConfig); InputStream dataIn = getServletContext().getResourceAsStream("/WEB-INF/data.tsv"); BufferedReader br = new BufferedReader(new InputStreamReader(dataIn, StandardCharsets.UTF_8)); String line = br.readLine(); final FieldType textNoNorms = new FieldType(TextField.TYPE_STORED); textNoNorms.setOmitNorms(true); while (line != null) { line = line.trim(); if (line.length() > 0) { //parse row and create a document StringTokenizer st = new StringTokenizer(line, "\t"); Document doc = new Document(); doc.add(new Field("location", st.nextToken(), textNoNorms)); doc.add(new Field("salary", st.nextToken(), textNoNorms)); doc.add(new Field("type", st.nextToken(), textNoNorms)); doc.add(new Field("description", st.nextToken(), textNoNorms)); writer.addDocument(doc); } line = br.readLine(); } writer.close(); //open searcher // this example never closes it reader! IndexReader reader = DirectoryReader.open(rd); searcher = new IndexSearcher(reader); } }