C # Convert PDF to text

Update

April February 27, 2014:This article initially only describes how to use product_box to parse PDF files. Now it has been extended to include routines using IFilter and iTextSharp.

This article and the corresponding Visual Studio project have been updated to the latest product_box version (1.8.4 ). You can download the complete project from the http://www.squarepdf.net/how-to-convert-pdf-to-text-in-net-sample-project/ that contains all the dependencies (which is tricky to remove dependencies ).

How to parse PDF files

There are several main methods for extracting text from a PDF file in. NET:

• Microsoft IFilter interface and Adobe IFilter implementation;

• ITextSharp;

• Product_box.

Unfortunately, these PDF resolution schemes are not perfect. We will discuss these methods below.

Adobe PDF IFilter

To use the IFilter interface to parse PDF files, you need:

• Windows 2000 or later versions

• Adobe Acrobat or Reader 7.0.5 + (or a separate Adobe PDF IFilter [adobe.com])

• IFilter COM encapsulation class [dotlucene.net]

Sample Code:

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using IFilter; // ... public static string ExtractTextFromPdf(string path) {  return DefaultParser.Extract(path); }

Disadvantages:

ITextSharp

ITextSharp (http://sourceforge.net/projects/itextsharp/) is a Java PDF operating library iText (http://itextpdf.com/). NET output. It mainly focuses on editing PDF files rather than reading them, but it certainly supports extracting text from PDF files (though a little small ).

Routine:

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using iTextSharp.text.pdf;using iTextSharp.text.pdf.parser; // ...  public static string ExtractTextFromPdf(string path){  using (PdfReader reader = new PdfReader(path))  {    StringBuilder text = new StringBuilder();     for (int i = 1; i <= reader.NumberOfPages; i++)    {        text.Append(PdfTextExtractor.GetTextFromPage(reader, i));    }     return text.ToString();  }}

Letter of Credit: Member No. 10364982

Disadvantages:

Product_box

Consumer box is another Java PDF class library. It can also be used with the original Java Lucene (see luceneworkflow document ).

Fortunately, javasbox has a. NET version developed using IKVM. NET (you only need to access the javasbox download page ).

To use consumer box in. NET, you need to reference:

• IKVM. OpenJDK. Core. dll

• IKVM. OpenJDK. SwingAWT. dll

• Pdfbox-1.8.4.dll

And copy the following files to the bin Folder:

• Commons-logging.dll

• Fontbox-1.8.4.dll

• IKVM. OpenJDK. Util. dll

• IKVM. Runtime. dll

Using product_box to parse PDF is very simple:

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using org.apache.pdfbox.pdmodel;using org.apache.pdfbox.util; // ... private static string ExtractTextFromPdf(string path){  PDDocument doc = null;  try {    doc = PDDocument.load(path)    PDFTextStripper stripper = new PDFTextStripper();    return stripper.getText(doc);  }  finally {    if (doc != null) {      doc.close();    }  }}

The size after compilation is about 18 MB:

• IKVM. OpenJDK. Core. dll (4 MB)

• IKVM. OpenJDK. SwingAWT. dll (6 MB)

• Pdfbox-1.8.4.dll (4 MB)

• Commons-logging.dll (82 kB)

• Fontbox-1.8.4.dll (180 kB)

• IKVM. OpenJDK. Util. dll (2 MB)

• IKVM. Runtime. dll (1 MB)

Speed: It takes 13 seconds to parse the U. S. Copyright Act PDF (5.1 MB) file.

Thanks to the improvement suggestions provided by bobrien100.

Disadvantages:

Related information

• You can see this article (and subsequent updates) on SquarePDF. NET ).

Address: http://www.codeproject.com/Articles/12445/Converting-PDF-to-Text-in-C