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}