    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 */
    017
    018package org.apache.lucene.demo.xmlparser;
    019
    020import java.io.BufferedReader;
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.InputStreamReader;
    024import java.util.Enumeration;
    025import java.util.Properties;
    026import java.util.StringTokenizer;
    027import javax.servlet.RequestDispatcher;
    028import javax.servlet.ServletConfig;
    029import javax.servlet.ServletException;
    030import javax.servlet.http.HttpServlet;
    031import javax.servlet.http.HttpServletRequest;
    032import javax.servlet.http.HttpServletResponse;
    033
    034import org.apache.lucene.analysis.Analyzer;
    035import org.apache.lucene.analysis.standard.StandardAnalyzer;
    036import org.apache.lucene.document.Document;
    037import org.apache.lucene.document.Field;
    038import org.apache.lucene.document.FieldType;
    039import org.apache.lucene.document.TextField;
    040import org.apache.lucene.index.DirectoryReader;
    041import org.apache.lucene.index.IndexReader;
    042import org.apache.lucene.index.IndexWriter;
    043import org.apache.lucene.index.IndexWriterConfig;
    044import org.apache.lucene.queryparser.xml.CorePlusExtensionsParser;
    045import org.apache.lucene.queryparser.xml.QueryTemplateManager;
    046import org.apache.lucene.search.IndexSearcher;
    047import org.apache.lucene.search.Query;
    048import org.apache.lucene.search.ScoreDoc;
    049import org.apache.lucene.search.TopDocs;
    050import org.apache.lucene.store.RAMDirectory;
    051import org.apache.lucene.util.IOUtils;
    052import org.apache.lucene.util.Version;
    053
    054/**
    055 * Example servlet that uses the XML queryparser.
    056 * <p>
    057 * NOTE: you must provide CSV data in <code>/WEB-INF/data.tsv</code>
    058 * for the demo to work!
    059 */
    060public class FormBasedXmlQueryDemo extends HttpServlet {
    061
    062  private QueryTemplateManager queryTemplateManager;
    063  private CorePlusExtensionsParser xmlParser;
    064  private IndexSearcher searcher;
    065  private Analyzer analyzer = new StandardAnalyzer(org.apache.lucene.util.Version.LUCENE_CURRENT);
    066
    067  /** for instantiation by the servlet container */
    068  public FormBasedXmlQueryDemo() {}
    069
    070  @Override
    071  public void init(ServletConfig config) throws ServletException {
    072    super.init(config);
    073    try {
    074      openExampleIndex();
    075
    076      //load servlet configuration settings
    077      String xslFile = config.getInitParameter("xslFile");
    078      String defaultStandardQueryParserField = config.getInitParameter("defaultStandardQueryParserField");
    079
    080
    081      //Load and cache choice of XSL query template using QueryTemplateManager
    082      queryTemplateManager = new QueryTemplateManager(
    083          getServletContext().getResourceAsStream("/WEB-INF/" + xslFile));
    084
    085      //initialize an XML Query Parser for use by all threads
    086      xmlParser = new CorePlusExtensionsParser(defaultStandardQueryParserField, analyzer);
    087    } catch (Exception e) {
    088      throw new ServletException("Error loading query template", e);
    089    }
    090  }
    091
    092  @Override
    093  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    094    //Take all completed form fields and add to a Properties object
    095    Properties completedFormFields = new Properties();
    096    Enumeration<?> pNames = request.getParameterNames();
    097    while (pNames.hasMoreElements()) {
    098      String propName = (String) pNames.nextElement();
    099      String value = request.getParameter(propName);
    100      if ((value != null) && (value.trim().length() > 0)) {
    101        completedFormFields.setProperty(propName, value);
    102      }
    103    }
    104
    105    try {
    106      //Create an XML query by populating template with given user criteria
    107      org.w3c.dom.Document xmlQuery = queryTemplateManager.getQueryAsDOM(completedFormFields);
    108
    109      //Parse the XML to produce a Lucene query
    110      Query query = xmlParser.getQuery(xmlQuery.getDocumentElement());
    111
    112      //Run the query
    113      TopDocs topDocs = searcher.search(query, 10);
    114
    115      //and package the results and forward to JSP
    116      if (topDocs != null) {
    117        ScoreDoc[] sd = topDocs.scoreDocs;
    118        Document[] results = new Document[sd.length];
    119        for (int i = 0; i < results.length; i++) {
    120          results[i] = searcher.doc(sd[i].doc);
    121          request.setAttribute("results", results);
    122        }
    123      }
    124      RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/index.jsp");
    125      dispatcher.forward(request, response);
    126    }
    127    catch (Exception e) {
    128      throw new ServletException("Error processing query", e);
    129    }
    130  }
    131
    132  private void openExampleIndex() throws IOException {
    133    //Create a RAM-based index from our test data file
    134    RAMDirectory rd = new RAMDirectory();
    135    IndexWriterConfig iwConfig = new IndexWriterConfig(Version.LUCENE_40, analyzer);
    136    IndexWriter writer = new IndexWriter(rd, iwConfig);
    137    InputStream dataIn = getServletContext().getResourceAsStream("/WEB-INF/data.tsv");
    138    BufferedReader br = new BufferedReader(new InputStreamReader(dataIn, IOUtils.CHARSET_UTF_8));
    139    String line = br.readLine();
    140    final FieldType textNoNorms = new FieldType(TextField.TYPE_STORED);
    141    textNoNorms.setOmitNorms(true);
    142    while (line != null) {
    143      line = line.trim();
    144      if (line.length() > 0) {
    145        //parse row and create a document
    146        StringTokenizer st = new StringTokenizer(line, "\t");
    147        Document doc = new Document();
    148        doc.add(new Field("location", st.nextToken(), textNoNorms));
    149        doc.add(new Field("salary", st.nextToken(), textNoNorms));
    150        doc.add(new Field("type", st.nextToken(), textNoNorms));
    151        doc.add(new Field("description", st.nextToken(), textNoNorms));
    152        writer.addDocument(doc);
    153      }
    154      line = br.readLine();
    155    }
    156    writer.close();
    157
    158    //open searcher
    159    // this example never closes it reader!
    160    IndexReader reader = DirectoryReader.open(rd);
    161    searcher = new IndexSearcher(reader);
    162  }
    163}