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 fr.univ_tours.etu.searcher; import fr.univ_tours.etu.nlp.CoreNlpTokenizer; import fr.univ_tours.etu.nlp.NlpNeTokenizer; import fr.univ_tours.etu.pdf.*; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.Reader; import java.io.StringReader; import java.io.StringWriter; import java.net.URL; import java.net.URLConnection; import java.util.Map; import java.util.HashMap; import java.util.List; import java.util.Calendar; import java.util.Date; import java.util.Properties; import org.apache.lucene.document.DateTools; import org.apache.lucene.document.Document; import org.apache.lucene.document.Field; import org.apache.lucene.document.FieldType; import org.apache.lucene.document.StringField; import org.apache.lucene.document.TextField; import org.apache.lucene.index.IndexOptions; import org.apache.pdfbox.exceptions.InvalidPasswordException; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDDocumentInformation; import org.apache.pdfbox.util.PDFTextStripper; /** * This class is used to create a document for the lucene search engine. This should easily plug into the IndexPDFFiles * that comes with the lucene project. This class will populate the following fields. * <table> * <tr> * <th>Lucene Field Name</th> * <th>Description</th> * </tr> * <tr> * <td>path</td> * <td>File system path if loaded from a file</td> * </tr> * <tr> * <td>url</td> * <td>URL to PDF document</td> * </tr> * <tr> * <td>contents</td> * <td>Entire contents of PDF document, indexed but not stored</td> * </tr> * <tr> * <td>summary</td> * <td>First 500 characters of content</td> * </tr> * <tr> * <td>modified</td> * <td>The modified date/time according to the url or path</td> * </tr> * <tr> * <td>uid</td> * <td>A unique identifier for the Lucene document.</td> * </tr> * <tr> * <td>CreationDate</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>Creator</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>Keywords</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>ModificationDate</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>Producer</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>Subject</td> * <td>From PDF meta-data if available</td> * </tr> * <tr> * <td>Trapped</td> * <td>From PDF meta-data if available</td> * </tr> * </table> * * @author Ben Litchfield * */ public class LucenePDFDocument { private static final char FILE_SEPARATOR = System.getProperty("file.separator").charAt(0); // given caveat of increased search times when using // MICROSECOND, only use SECOND by default private static final DateTools.Resolution DATE_TIME_RES = DateTools.Resolution.SECOND; private PDFTextStripper stripper = null; /** not Indexed, tokenized, stored. */ public static final FieldType TYPE_STORED_NOT_INDEXED = new FieldType(); static { TYPE_STORED_NOT_INDEXED.setIndexOptions(IndexOptions.NONE); TYPE_STORED_NOT_INDEXED.setStored(true); TYPE_STORED_NOT_INDEXED.setTokenized(true); TYPE_STORED_NOT_INDEXED.freeze(); } /** * Constructor. */ public LucenePDFDocument() { } /** * Set the text stripper that will be used during extraction. * * @param aStripper The new pdf text stripper. */ public void setTextStripper(PDFTextStripper aStripper) { stripper = aStripper; } private static String timeToString(long time) { return DateTools.timeToString(time, DATE_TIME_RES); } private void addKeywordField(Document document, String name, String value) { if (value != null) { document.add(new StringField(name, value, Field.Store.YES)); } } private void addTextField(Document document, String name, Reader value) { if (value != null) { document.add(new TextField(name, value)); } } private void addTextField(Document document, String name, String value) { if (value != null) { document.add(new TextField(name, value, Field.Store.YES)); } } private void addTextField(Document document, String name, Date value) { if (value != null) { addTextField(document, name, DateTools.dateToString(value, DATE_TIME_RES)); } } private void addTextField(Document document, String name, Calendar value) { if (value != null) { addTextField(document, name, value.getTime()); } } private static void addUnindexedField(Document document, String name, String value) { if (value != null) { document.add(new Field(name, value, TYPE_STORED_NOT_INDEXED)); } } private void addUnstoredKeywordField(Document document, String name, String value) { if (value != null) { document.add(new Field(name, value, TextField.TYPE_NOT_STORED)); } } /** * Convert the PDF stream to a lucene document. * * @param is The input stream. * @return The input stream converted to a lucene document. * @throws IOException If there is an error converting the PDF. */ public Document convertDocument(InputStream is) throws IOException { Document document = new Document(); addContent(document, is, "<inputstream>"); return document; } /** * This will take a reference to a PDF document and create a lucene document. * * @param file A reference to a PDF document. * @return The converted lucene document. * * @throws IOException If there is an exception while converting the document. */ public Document convertDocument(File file) throws IOException { Document document = new Document(); // Add the url as a field named "url". Use an UnIndexed field, so // that the url is just stored with the document, but is not searchable. addUnindexedField(document, "path", file.getPath()); addUnindexedField(document, "url", file.getPath().replace(FILE_SEPARATOR, '/')); // Add the last modified date of the file a field named "modified". Use a // Keyword field, so that it's searchable, but so that no attempt is made // to tokenize the field into words. addKeywordField(document, "modified", timeToString(file.lastModified())); String uid = createUID(file); // Add the uid as a field, so that index can be incrementally maintained. // This field is not stored with document, it is indexed, but it is not // tokenized prior to indexing. addUnstoredKeywordField(document, "uid", uid); FileInputStream input = null; try { input = new FileInputStream(file); addContent(document, input, file.getPath()); } finally { if (input != null) { input.close(); } } // return the document return document; } /** * Convert the document from a PDF to a lucene document. * * @param url A url to a PDF document. * @return The PDF converted to a lucene document. * @throws IOException If there is an error while converting the document. */ public Document convertDocument(URL url) throws IOException { Document document = new Document(); URLConnection connection = url.openConnection(); connection.connect(); // Add the url as a field named "url". Use an UnIndexed field, so // that the url is just stored with the document, but is not searchable. addUnindexedField(document, "url", url.toExternalForm()); // Add the last modified date of the file a field named "modified". Use a // Keyword field, so that it's searchable, but so that no attempt is made // to tokenize the field into words. addKeywordField(document, "modified", timeToString(connection.getLastModified())); String uid = createUID(url, connection.getLastModified()); // Add the uid as a field, so that index can be incrementally maintained. // This field is not stored with document, it is indexed, but it is not // tokenized prior to indexing. addUnstoredKeywordField(document, "uid", uid); InputStream input = null; try { input = connection.getInputStream(); addContent(document, input, url.toExternalForm()); } finally { if (input != null) { input.close(); } } // return the document return document; } /** * This will get a lucene document from a PDF file. * * @param is The stream to read the PDF from. * * @return The lucene document. * * @throws IOException If there is an error parsing or indexing the document. */ public static Document getDocument(InputStream is) throws IOException { LucenePDFDocument converter = new LucenePDFDocument(); return converter.convertDocument(is); } /** * This will get a lucene document from a PDF file. * * @param file The file to get the document for. * * @return The lucene document. * * @throws IOException If there is an error parsing or indexing the document. */ public static Document getDocument(File file) throws IOException { LucenePDFDocument converter = new LucenePDFDocument(); return converter.convertDocument(file); } /** * This will get a lucene document from a PDF file. * * @param url The file to get the document for. * * @return The lucene document. * * @throws IOException If there is an error parsing or indexing the document. */ public static Document getDocument(URL url) throws IOException { LucenePDFDocument converter = new LucenePDFDocument(); return converter.convertDocument(url); } /** * This will add the contents to the lucene document. * * @param document The document to add the contents to. * @param is The stream to get the contents from. * @param documentLocation The location of the document, used just for debug messages. * * @throws IOException If there is an error parsing the document. */ private void addContent(Document document, InputStream is, String documentLocation) throws IOException { PDDocument pdfDocument = null; try { pdfDocument = PDDocument.load(is); // create a writer where to append the text content. StringWriter writer = new StringWriter(); if (stripper == null) { stripper = new PDFTextStripper(); } stripper.writeText(pdfDocument, writer); // Note: the buffer to string operation is costless; // the char array value of the writer buffer and the content string // is shared as long as the buffer content is not modified, which will // not occur here. String contents = writer.getBuffer().toString(); StringReader reader = new StringReader(contents); // Add the tag-stripped contents as a Reader-valued Text field so it will // get tokenized and indexed. addTextField(document, "contents", reader); PDDocumentInformation info = pdfDocument.getDocumentInformation(); if (info != null) { addTextField(document, "Author", info.getAuthor()); addTextField(document, "CreationDate", info.getCreationDate()); addTextField(document, "Creator", info.getCreator()); addTextField(document, "Keywords", info.getKeywords()); addTextField(document, "ModificationDate", info.getModificationDate()); addTextField(document, "Producer", info.getProducer()); addTextField(document, "Subject", info.getSubject()); addTextField(document, "Title", info.getTitle()); addTextField(document, "Trapped", info.getTrapped()); } int summarySize = Math.min(contents.length(), 1500); String summary = contents.substring(0, summarySize); // Add the summary as an UnIndexed field, so that it is stored and returned // with hit documents for display. addUnindexedField(document, "summary", summary); } finally { if (pdfDocument != null) { pdfDocument.close(); } } } /** * Create an UID for the given file using the given time. * * @param url the file we have to create an UID for * @param time the time to used to the UID * * @return the created UID */ public static String createUID(URL url, long time) { return url.toExternalForm().replace(FILE_SEPARATOR, '\u0000') + "\u0000" + timeToString(time); } /** * Create an UID for the given file. * * @param file the file we have to create an UID for * * @return the created UID */ public static String createUID(File file) { return file.getPath().replace(FILE_SEPARATOR, '\u0000') + "\u0000" + timeToString(file.lastModified()); } }