187 lines
8.6 KiB
XML
187 lines
8.6 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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See the License for the specific language governing permissions and
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limitations under the License.
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====================================================================
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-->
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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.3//EN" "./dtd/document-v13.dtd">
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<document>
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<header>
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<title>Apache POI - Text Extraction</title>
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<authors>
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<person id="NB" name="Nick Burch" email="nick@apache.org"/>
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</authors>
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</header>
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<body>
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<section><title>Overview</title>
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<p>For a number of years now, Apache POI has provided basic
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text extraction for all the project supported file formats. In
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addition, as well as the (plain) text, these provides access to
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the metadata associated with a given file, such as title and
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author.</p>
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<p>For more advanced text extraction needs, including Rich Text
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extraction (such as formatting and styling), along with XML and
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HTML output, Apache POI works closely with
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<link href="http://tika.apache.org/">Apache Tika</link> to deliver
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POI-powered Tika Parsers for all the project supported file formats.</p>
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<p>If you are after turn-key text extraction, including the latest
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support, styles etc, you are strongly advised to make use of
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<link href="http://tika.apache.org/">Apache Tika</link>, which builds
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on top of POI to provide Text and Metadata extraction. If you wish
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to have something very simple and stand-alone, or you wish to make
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heavy modificiations, then the POI provided text extractors documented
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below might be a better fit for your needs.</p>
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</section>
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<section><title>Common functionality</title>
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<p>All of the POI text extractors extend from
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<em>org.apache.poi.POITextExtractor</em>. This provides a common
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method across all extractors, getText(). For many cases, the text
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returned will be all you need. However, many extractors do provide
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more targetted text extraction methods, so you may wish to use
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these in some cases.</p>
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<p>All POIFS / OLE 2 based text extractors also extend from
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<em>org.apache.poi.POIOLE2TextExtractor</em>. This additionally
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provides common methods to get at the <link href="hpfs/">HPFS
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document metadata</link>.</p>
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<p>All OOXML based text extractors (available in POI 3.5 and later)
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also extend from
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<em>org.apache.poi.POIOOXMLTextExtractor</em>. This additionally
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provides common methods to get at the OOXML metadata.</p>
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</section>
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<section><title>Text Extractor Factory</title>
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<p>As part of the addition of OOXML support in Apache POI 3.5, there
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is a common class to select the appropriate POI text extractor for
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you. <em>org.apache.poi.extractor.ExtractorFactory</em> provides a
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similar function to WorkbookFactory. You simply pass it an
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InputStream, a File, a POIFSFileSystem or a OOXML Package. It
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figures out the correct text extractor for you, and returns it.</p>
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<p>For complete detection and text extractor auto-selection, users
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are strongly encouraged to investigate
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<link href="http://tika.apache.org/">Apache Tika</link>.</p>
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</section>
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<section><title>Excel</title>
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<p>For .xls files, there is
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<em>org.apache.poi.hssf.extractor.ExcelExtractor</em>, which will
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return text, optionally with formulas instead of their contents.
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Those using POI 3.5 can also use
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<em>org.apache.poi.xssf.extractor.XSSFExcelExtractor</em>, to perform
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a similar task for .xlsx files.</p>
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<p>In addition, there is a second text extractor for .xls files,
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<em>org.apache.poi.hssf.extractor.EventBasedExcelExtractor</em>. This
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is based on the streaming EventUserModel code, and will generally
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deliver a lower memory footprint for extraction. However, it will
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have problems correctly outputting more complex formulas, as it
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works with records as they pass, and so doesn't have access to all
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parts of complex and shared formulas.</p>
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</section>
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<section><title>Word</title>
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<p>For .doc files from Word 97 - Word 2003, in scratchpad there is
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<em>org.apache.poi.hwpf.extractor.WordExtractor</em>, which will
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return text for your document.</p>
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<p>Those using POI 3.7 can also extract simple textual content from
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older Word 6 and Word 95 files, using the scratchpad class
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<em>org.apache.poi.hwpf.extractor.Word6Extractor</em>.</p>
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<p>Since POI 3.5, it is possible to use
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<em>org.apache.poi.xwpf.extractor.XPFFWordExtractor</em>, to perform
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text extraction for .docx files.</p>
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</section>
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<section><title>PowerPoint</title>
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<p>For .ppt files, in scratchpad there is
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<em>org.apache.poi.hslf.extractor.PowerPointExtractor</em>, which
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will return text for your slideshow, optionally restricted to just
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slides text or notes text. Those using POI 3.5 can also use
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<em>org.apache.poi.xslf.extractor.XSLFPowerPointExtractor</em>, to
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perform a similar task for .pptx files.</p>
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</section>
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<section><title>Publisher</title>
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<p>For .pub files, in scratchpad there is
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<em>org.apache.poi.hpbf.extractor.PublisherExtractor</em>, which
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will return text for your file.</p>
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</section>
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<section><title>Visio</title>
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<p>For .vsd files, in scratchpad there is
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<em>org.apache.poi.hdgf.extractor.VisioTextExtractor</em>, which
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will return text for your file.</p>
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</section>
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<section><title>Embedded Objects</title>
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<p>Extractors already exist for Excel, Word, PowerPoint and Visio;
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if one of these objects is embedded into a worksheet, the ExtractorFactory class can be used to recover an extractor for it.
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</p>
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<source>
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FileInputStream fis = new FileInputStream(inputFile);
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POIFSFileSystem fileSystem = new POIFSFileSystem(fis);
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// Firstly, get an extractor for the Workbook
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POIOLE2TextExtractor oleTextExtractor =
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ExtractorFactory.createExtractor(fileSystem);
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// Then a List of extractors for any embedded Excel, Word, PowerPoint
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// or Visio objects embedded into it.
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POITextExtractor[] embeddedExtractors =
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ExtractorFactory.getEmbededDocsTextExtractors(oleTextExtractor);
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for (POITextExtractor textExtractor : embeddedExtractors) {
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// If the embedded object was an Excel spreadsheet.
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if (textExtractor instanceof ExcelExtractor) {
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ExcelExtractor excelExtractor = (ExcelExtractor) textExtractor;
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System.out.println(excelExtractor.getText());
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}
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// A Word Document
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else if (textExtractor instanceof WordExtractor) {
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WordExtractor wordExtractor = (WordExtractor) textExtractor;
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String[] paragraphText = wordExtractor.getParagraphText();
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for (String paragraph : paragraphText) {
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System.out.println(paragraph);
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}
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// Display the document's header and footer text
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System.out.println("Footer text: " + wordExtractor.getFooterText());
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System.out.println("Header text: " + wordExtractor.getHeaderText());
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}
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// PowerPoint Presentation.
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else if (textExtractor instanceof PowerPointExtractor) {
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PowerPointExtractor powerPointExtractor =
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(PowerPointExtractor) textExtractor;
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System.out.println("Text: " + powerPointExtractor.getText());
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System.out.println("Notes: " + powerPointExtractor.getNotes());
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}
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// Visio Drawing
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else if (textExtractor instanceof VisioTextExtractor) {
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VisioTextExtractor visioTextExtractor =
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(VisioTextExtractor) textExtractor;
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System.out.println("Text: " + visioTextExtractor.getText());
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}
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}
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</source>
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</section>
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</body>
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<footer>
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<legal>
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Copyright (c) @year@ The Apache Software Foundation. All rights reserved.
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<br />
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Apache POI, POI, Apache, the Apache feather logo, and the Apache
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POI project logo are trademarks of The Apache Software Foundation.
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</legal>
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</footer>
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</document>
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