io.github.astrapisixtynine.pdf.to.text.PdfToTextExtensions Maven / Gradle / Ivy
package io.github.astrapisixtynine.pdf.to.text;
import java.awt.image.BufferedImage;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import org.apache.pdfbox.Loader;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.text.PDFTextStripper;
import io.github.astrapi69.file.create.FileFactory;
import io.github.astrapi69.file.read.ReadFileExtensions;
import io.github.astrapi69.file.write.StoreFileExtensions;
import io.github.astrapi69.io.file.FileExtension;
import io.github.astrapi69.io.file.FilenameExtensions;
import io.github.astrapi69.io.shell.LinuxShellExecutor;
import io.github.astrapisixtynine.pdf.to.text.info.ConversionResult;
import net.sourceforge.tess4j.Tesseract;
import net.sourceforge.tess4j.TesseractException;
/**
* The class {@link PdfToTextExtensions} provides functionality to convert a PDF file into a text
* file using either direct text extraction or Optical Character Recognition (OCR)
*/
public final class PdfToTextExtensions
{
/**
* Private constructor to prevent instantiation
*/
private PdfToTextExtensions()
{
}
/**
* Converts a PDF file to a text file extracting text from all pages
*
* @param pdfFile
* the input PDF file
* @param resultDir
* the directory where the output text file will be stored
* @return the generated text file
* @throws IOException
* if an I/O error occurs
*/
public static File pdfToText(File pdfFile, File resultDir) throws IOException
{
int numberOfPages;
try (PDDocument document = Loader.loadPDF(pdfFile))
{
numberOfPages = document.getNumberOfPages();
}
return pdfToText(pdfFile, resultDir, 0, numberOfPages);
}
/**
* Converts a PDF file to a text file, with the option to specify a range of pages to extract
*
* @param pdfFile
* the input PDF file
* @param resultDir
* the directory where the output text file will be stored
* @param startPageValue
* the starting page number
* @param endPageValue
* the ending page number
* @return the generated text file
* @throws IOException
* if an I/O error occurs
*/
public static File pdfToText(File pdfFile, File resultDir, int startPageValue, int endPageValue)
throws IOException
{
String txtFileName;
String fileName;
fileName = FilenameExtensions.getFilenameWithoutExtension(pdfFile);
txtFileName = fileName + FileExtension.TXT.getExtension();
File resultTextFile = FileFactory.newFile(resultDir, txtFileName);
try (PDDocument document = Loader.loadPDF(pdfFile);
BufferedWriter wr = new BufferedWriter(
new OutputStreamWriter(new FileOutputStream(resultTextFile))))
{
PDFTextStripper stripper = new PDFTextStripper();
stripper.setStartPage(startPageValue); // Start extracting from first page
stripper.setEndPage(endPageValue); // Extract till the end
stripper.writeText(document, wr);
}
return resultTextFile;
}
/**
* Converts a PDF file to text using image processing and OCR
*
* @param pdfFile
* the input PDF file
* @param outputDir
* the directory where the output files will be stored
* @return the result of the conversion containing image files, text files, and the final result
* text file
* @throws IOException
* if an I/O error occurs
* @throws InterruptedException
* if the process is interrupted
*/
public static ConversionResult convertPdfToTextfile(File pdfFile, File outputDir)
throws IOException, InterruptedException
{
String txtFileName;
String fileName;
fileName = FilenameExtensions.getFilenameWithoutExtension(pdfFile);
txtFileName = fileName + FileExtension.TXT.getExtension();
File resultTextFile = FileFactory.newFile(outputDir, txtFileName);
// step 1: convert the pdf file to image files
List imageFiles = getImageFiles(pdfFile, outputDir);
// step 2: convert the image files to text files
String shellPath = "/bin/sh";
List textFiles = getTextFiles(imageFiles, outputDir, shellPath);
// step 3: concatenate all text files to one
concatenateAll(textFiles, resultTextFile);
return ConversionResult.builder().imageFiles(imageFiles).textFiles(textFiles)
.resultTextFile(resultTextFile).build();
}
/**
* Converts image files into text files using Tesseract OCR
*
* @param imageFiles
* the list of image files to be processed
* @param resultDir
* the directory where the text files will be stored
* @param shellPath
* the shell path for executing commands
* @return the list of generated text files
* @throws IOException
* if an I/O error occurs
* @throws InterruptedException
* if the process is interrupted
*/
public static List getTextFiles(List imageFiles, File resultDir, String shellPath)
throws IOException, InterruptedException
{
String output;
String command;
String commandPrefix;
commandPrefix = "tesseract";
String executionPath = resultDir.toString();
List textFiles = new ArrayList<>();
for (int page = 0; page < imageFiles.size(); ++page)
{
File imageFile = imageFiles.get(page);
String imageFileName = imageFile.getName();
String textFileName = FilenameExtensions.getFilenameWithoutExtension(imageFile);
command = commandPrefix + " " + imageFileName + " " + textFileName + " -l deu";
output = LinuxShellExecutor.execute(shellPath, executionPath, command);
System.out.println(output);
File textFile = new File(resultDir, textFileName + ".txt");
textFiles.add(textFile);
}
return textFiles;
}
/**
* Converts a PDF file into image files for each page
*
* @param pdfFile
* the input PDF file
* @param outputDir
* the directory where the image files will be stored
* @return the list of generated image files
* @throws IOException
* if an I/O error occurs
*/
public static List getImageFiles(File pdfFile, File outputDir) throws IOException
{
List imageFiles = new ArrayList<>();
String fileName = FilenameExtensions.getFilenameWithoutExtension(pdfFile);
try (PDDocument document = Loader.loadPDF(pdfFile))
{
PDFRenderer pdfRenderer = new PDFRenderer(document);
for (int page = 0; page < document.getNumberOfPages(); ++page)
{
BufferedImage image = pdfRenderer.renderImageWithDPI(page, 300, ImageType.RGB);
File imageFile = new File(outputDir, fileName + "page_" + (page + 1) + ".png");
ImageIO.write(image, "png", imageFile);
imageFiles.add(imageFile);
}
}
return imageFiles;
}
/**
* Concatenates the contents of all text files into a single text file
*
* @param textFiles
* the list of text files to concatenate
* @param resultTextFile
* the final result text file that will contain the concatenated content
* @throws IOException
* if an I/O error occurs
*/
public static void concatenateAll(List textFiles, File resultTextFile) throws IOException
{
StringBuilder text = new StringBuilder();
for (int i = 0; i < textFiles.size(); ++i)
{
File textFile = textFiles.get(i);
String content = ReadFileExtensions.fromFile(textFile);
text.append(content);
}
StoreFileExtensions.toFile(resultTextFile, text.toString());
}
/**
* Extracts text from a single image file using Tesseract OCR
*
* @param imageFile
* the image file to process
* @param datapath
* the path to Tesseract data files
* @param language
* the language to use for OCR
* @return the extracted text
* @throws TesseractException
* if an error occurs during OCR
*/
public static String extractTextFromImage(File imageFile, String datapath, String language)
throws TesseractException
{
Tesseract tesseract = new Tesseract();
tesseract.setDatapath(datapath);
tesseract.setLanguage(language);
return tesseract.doOCR(imageFile);
}
}
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