LucenePDFDocument.java
/*
* 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.pdfbox.examples.lucene;
import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.net.URL;
import java.net.URLConnection;
import java.nio.file.FileSystems;
import java.util.Calendar;
import java.util.Date;
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.Loader;
import org.apache.pdfbox.io.RandomAccessRead;
import org.apache.pdfbox.io.RandomAccessReadBuffer;
import org.apache.pdfbox.io.RandomAccessReadBufferedFile;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDDocumentInformation;
import org.apache.pdfbox.pdmodel.encryption.InvalidPasswordException;
import org.apache.pdfbox.text.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>
* <caption></caption>
* <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 = FileSystems.getDefault().getSeparator().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));
}
}
/**
* 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);
addContent(document, new RandomAccessReadBufferedFile(file), file.getPath());
// 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);
addContent(document,
RandomAccessReadBuffer.createBufferFromStream(connection.getInputStream()),
url.toExternalForm());
// return the document
return document;
}
/**
* 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 source The source to get the content 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, RandomAccessRead source, String documentLocation)
throws IOException
{
try (PDDocument pdfDocument = Loader.loadPDF(source))
{
// 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(), 500);
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);
}
catch (InvalidPasswordException e)
{
// they didn't supply a password and the default of "" was wrong.
throw new IOException("Error: The document(" + documentLocation + ") is encrypted and will not be indexed.", e);
}
}
/**
* 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());
}
}