/*
* 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.lucene.demo.xmlparser;
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;
/**
* 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(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);
}
}