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  @Override
068  public void init(ServletConfig config) throws ServletException {
069    super.init(config);
070    try {
071      openExampleIndex();
072
073      //load servlet configuration settings
074      String xslFile = config.getInitParameter("xslFile");
075      String defaultStandardQueryParserField = config.getInitParameter("defaultStandardQueryParserField");
076
077
078      //Load and cache choice of XSL query template using QueryTemplateManager
079      queryTemplateManager = new QueryTemplateManager(
080          getServletContext().getResourceAsStream("/WEB-INF/" + xslFile));
081
082      //initialize an XML Query Parser for use by all threads
083      xmlParser = new CorePlusExtensionsParser(defaultStandardQueryParserField, analyzer);
084    } catch (Exception e) {
085      throw new ServletException("Error loading query template", e);
086    }
087  }
088
089  @Override
090  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
091    //Take all completed form fields and add to a Properties object
092    Properties completedFormFields = new Properties();
093    Enumeration<?> pNames = request.getParameterNames();
094    while (pNames.hasMoreElements()) {
095      String propName = (String) pNames.nextElement();
096      String value = request.getParameter(propName);
097      if ((value != null) && (value.trim().length() > 0)) {
098        completedFormFields.setProperty(propName, value);
099      }
100    }
101
102    try {
103      //Create an XML query by populating template with given user criteria
104      org.w3c.dom.Document xmlQuery = queryTemplateManager.getQueryAsDOM(completedFormFields);
105
106      //Parse the XML to produce a Lucene query
107      Query query = xmlParser.getQuery(xmlQuery.getDocumentElement());
108
109      //Run the query
110      TopDocs topDocs = searcher.search(query, 10);
111
112      //and package the results and forward to JSP
113      if (topDocs != null) {
114        ScoreDoc[] sd = topDocs.scoreDocs;
115        Document[] results = new Document[sd.length];
116        for (int i = 0; i < results.length; i++) {
117          results[i] = searcher.doc(sd[i].doc);
118          request.setAttribute("results", results);
119        }
120      }
121      RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/index.jsp");
122      dispatcher.forward(request, response);
123    }
124    catch (Exception e) {
125      throw new ServletException("Error processing query", e);
126    }
127  }
128
129  private void openExampleIndex() throws IOException {
130    //Create a RAM-based index from our test data file
131    RAMDirectory rd = new RAMDirectory();
132    IndexWriterConfig iwConfig = new IndexWriterConfig(Version.LUCENE_40, analyzer);
133    IndexWriter writer = new IndexWriter(rd, iwConfig);
134    InputStream dataIn = getServletContext().getResourceAsStream("/WEB-INF/data.tsv");
135    BufferedReader br = new BufferedReader(new InputStreamReader(dataIn, IOUtils.CHARSET_UTF_8));
136    String line = br.readLine();
137    final FieldType textNoNorms = new FieldType(TextField.TYPE_STORED);
138    textNoNorms.setOmitNorms(true);
139    while (line != null) {
140      line = line.trim();
141      if (line.length() > 0) {
142        //parse row and create a document
143        StringTokenizer st = new StringTokenizer(line, "\t");
144        Document doc = new Document();
145        doc.add(new Field("location", st.nextToken(), textNoNorms));
146        doc.add(new Field("salary", st.nextToken(), textNoNorms));
147        doc.add(new Field("type", st.nextToken(), textNoNorms));
148        doc.add(new Field("description", st.nextToken(), textNoNorms));
149        writer.addDocument(doc);
150      }
151      line = br.readLine();
152    }
153    writer.close();
154
155    //open searcher
156    // this example never closes it reader!
157    IndexReader reader = DirectoryReader.open(rd);
158    searcher = new IndexSearcher(reader);
159  }
160}