How to OCR Images & Scanned PDFs using Java

`package com.muhimbi.app;

import com.muhimbi.ws.*;

import java.io.*;
import java.net.URL;
import java.util.List;

import javax.xml.bind.JAXBElement;
import javax.xml.namespace.QName;

public class WsClient {

private final static String DOCUMENTCONVERTERSERVICE_WSDL_LOCATION =
        "https://localhost:41734/Muhimbi.DocumentConverter.WebService/?wsdl";

private static ObjectFactory _objectFactory = new ObjectFactory();

public static void main(String[] args) {
    try {
      if (args.length != 1) {
        System.out.println("Please specify a single file name on the command line.");

      } else {
        // ** Process command line parameters
        String sourceDocumentPath = args[0];
        File file = new File(sourceDocumentPath);
        String fileName = getFileName(file);
        String fileExt = getFileExtension(file);

        System.out.println("Processing file " + sourceDocumentPath);

        // ** Initialise Web Service
        DocumentConverterService_Service dcss = new DocumentConverterService_Service(
            new URL(DOCUMENTCONVERTERSERVICE_WSDL_LOCATION),
            new QName("https://tempuri.org/", "DocumentConverterService"));
        DocumentConverterService dcs = dcss.getBasicHttpBindingDocumentConverterService();

        // ** Only call conversion if file extension is supported
        if (isFileExtensionSupported(fileExt, dcs)) {
          // ** Read source file from disk
          byte[] fileContent = readFile(sourceDocumentPath);

          // ** Converting the file
          OpenOptions openOptions = getOpenOptions(fileName, fileExt);
          ConversionSettings conversionSettings = getConversionSettings();
          byte[] convertedFile = dcs.convert(fileContent, openOptions, conversionSettings);

          // ** Writing converted file to file system
          String destinationDocumentPath = getPDFDocumentPath(file);
          writeFile(convertedFile, destinationDocumentPath);
          System.out.println("File converted successfully to " + destinationDocumentPath);

        } else {
          System.out.println("The file extension is not supported.");
        }
      }

    } catch (IOException e) {
      System.out.println(e.getMessage());
    } catch (DocumentConverterServiceGetConfigurationWebServiceFaultExceptionFaultFaultMessage e) {
      printException(e.getFaultInfo());
    } catch (DocumentConverterServiceConvertWebServiceFaultExceptionFaultFaultMessage e) {
      printException(e.getFaultInfo());
    }
}

public static OpenOptions getOpenOptions(String fileName, String fileExtension) {
    OpenOptions openOptions = new OpenOptions();
    // ** Set the minimum required open options. Additional options are available
    openOptions.setOriginalFileName(_objectFactory.createOpenOptionsOriginalFileName(fileName));
    openOptions.setFileExtension(_objectFactory.createOpenOptionsFileExtension(fileExtension));
    return openOptions;
}

public static ConversionSettings getConversionSettings() {
    ConversionSettings conversionSettings = new ConversionSettings();
    // ** Set the minimum required conversion settings. Additional settings are available
    conversionSettings.setQuality(ConversionQuality.OPTIMIZE_FOR_PRINT);
    conversionSettings.setRange(ConversionRange.ALL_DOCUMENTS);
    conversionSettings.getFidelity().add("Full");
    conversionSettings.setFormat(OutputFormat.PDF);
    conversionSettings.setOCRSettings(_objectFactory.createConversionSettingsOCRSettings(getOCRSettings()));
    return conversionSettings;
}

public static OCRSettings getOCRSettings() {
    OCRSettings ocrSettings = new OCRSettings();
    ocrSettings.setLanguage(_objectFactory.createOCRSettingsLanguage("eng"));
    ocrSettings.setPerformance(OCRPerformance.SLOW);
    ocrSettings.setWhiteList(_objectFactory.createOCRSettingsWhiteList(""));
    ocrSettings.setBlackList(_objectFactory.createOCRSettingsBlackList(""));
    return ocrSettings;
}

public static String getFileName(File file) {
    String fileName = file.getName();
    return fileName.substring(0, fileName.lastIndexOf('.'));
}

public static String getFileExtension(File file) {
    String fileName = file.getName();
    return fileName.substring(fileName.lastIndexOf('.') + 1, fileName.length());
}

public static String getPDFDocumentPath(File file) {
    String fileName = getFileName(file);
    String folder = file.getParent();
    if (folder == null) {
      folder = new File(file.getAbsolutePath()).getParent();
    }
    return folder + File.separatorChar + fileName + "_ocr."
        + OutputFormat.PDF.value();
}

public static byte[] readFile(String filepath) throws IOException {
    File file = new File(filepath);
    InputStream is = new FileInputStream(file);
    long length = file.length();
    byte[] bytes = new byte[(int) length];

    int offset = 0;
    int numRead;
    while (offset < bytes.length
        && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
      offset += numRead;
    }

    if (offset < bytes.length) {
      throw new IOException("Could not completely read file " + file.getName());
    }
    is.close();
    return bytes;
}

public static void writeFile(byte[] fileContent, String filepath)
      throws IOException {
    OutputStream os = new FileOutputStream(filepath);
    os.write(fileContent);
    os.close();
}

public static boolean isFileExtensionSupported(String extension, DocumentConverterService dcs)
    throws DocumentConverterServiceGetConfigurationWebServiceFaultExceptionFaultFaultMessage
    {
      Configuration configuration = dcs.getConfiguration();
      final JAXBElement<ArrayOfConverterConfiguration> converters = configuration.getConverters();
      final ArrayOfConverterConfiguration ofConverterConfiguration = converters.getValue();
      final List<ConverterConfiguration> cList = ofConverterConfiguration.getConverterConfiguration();

      for (ConverterConfiguration cc : cList) {
        final List<String> supportedExtension = cc.getSupportedFileExtensions()
            .getValue().getString();
        if (supportedExtension.contains(extension)) {
          return true;
        }
    }

    return false;
}

public static void printException(WebServiceFaultException serviceFaultException) {
    System.out.println(serviceFaultException.getExceptionType());
    JAXBElement<ArrayOfstring> element = serviceFaultException.getExceptionDetails();
    ArrayOfstring value = element.getValue();
    for (String msg : value.getString()) {
      System.out.println(msg);
    }
}

}`