Convert XPS to PDF in Java

Table of Contents#

1. Core Concepts
2. Typical Usage Scenarios
3. Common Pitfalls
4. Best Practices
5. Code Examples
6. Conclusion
7. FAQ
8. References

Core Concepts#

XPS#

XPS is based on XML and describes the content, layout, and appearance of a document. It uses XML to define text, graphics, and other elements, making it a platform - independent format. However, not all applications support XPS natively, which is why conversion to a more widely - supported format like PDF is often necessary.

PDF#

PDF is a universal document format that preserves the document's layout, fonts, and graphics across different devices and operating systems. It is supported by a vast number of applications, making it ideal for document sharing and archiving.

Java Libraries for Conversion#

To convert XPS to PDF in Java, we typically rely on third - party libraries. One such popular library is Apache PDFBox and another is JODConverter. These libraries provide APIs to read XPS files and generate PDF output.

Typical Usage Scenarios#

1. Document Sharing: When you need to share an XPS document with others who may not have XPS - viewing software, converting it to PDF ensures that the document can be opened and viewed on a wide range of devices.
2. Archiving: PDF is a more stable and widely - supported format for long - term archiving. Converting XPS files to PDF helps in maintaining the integrity of the documents over time.
3. Printing: Many printers have better support for PDF files than XPS. Converting XPS to PDF can simplify the printing process.

Common Pitfalls#

1. Dependency Management: Using third - party libraries means you need to manage their dependencies carefully. Incorrect versioning or missing dependencies can lead to runtime errors.
2. Memory Issues: Converting large XPS files can consume a significant amount of memory. If not handled properly, it can lead to OutOfMemoryError.
3. Font and Graphics Rendering: Some complex fonts or graphics in the XPS file may not be rendered correctly in the PDF. This can result in missing or distorted elements in the output.

Best Practices#

1. Proper Dependency Management: Use a build tool like Maven or Gradle to manage the dependencies of the libraries you are using. This ensures that the correct versions of the libraries are used and all dependencies are resolved.
2. Memory Optimization: When converting large files, process the document in chunks instead of loading the entire file into memory at once. You can also set appropriate heap size limits for your Java application.
3. Testing: Always test the conversion process with a variety of XPS files, including those with complex fonts and graphics, to ensure that the output PDF is of high quality.

Code Examples#

Using Apache PDFBox and JavaFX for XPS to PDF Conversion#

import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Scene;
import javafx.scene.image.WritableImage;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
 
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
 
public class XpsToPdfConverter {
 
    public static void convertXpsToPdf(String xpsFilePath, String pdfFilePath) throws IOException {
        // Create a new PDF document
        PDDocument pdfDocument = new PDDocument();
 
        // Use JavaFX WebView to load XPS file
        WebView webView = new WebView();
        WebEngine webEngine = webView.getEngine();
        webEngine.load(new File(xpsFilePath).toURI().toString());
 
        // Wait for the page to load
        try {
            Thread.sleep(5000); // Adjust the time as needed
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
 
        // Capture the web view as an image
        WritableImage snapshot = webView.snapshot(null, null);
        BufferedImage bufferedImage = SwingFXUtils.fromFXImage(snapshot, null);
 
        // Add a page to the PDF document
        PDPage page = new PDPage();
        pdfDocument.addPage(page);
 
        // Create a content stream for the page
        PDPageContentStream contentStream = new PDPageContentStream(pdfDocument, page);
 
        // Convert the image to a PDF image object
        PDImageXObject pdImage = PDImageXObject.createFromFileByContent(new File(pdfFilePath), pdfDocument);
 
        // Draw the image on the PDF page
        contentStream.drawImage(pdImage, 0, 0);
 
        // Close the content stream
        contentStream.close();
 
        // Save the PDF document
        pdfDocument.save(pdfFilePath);
 
        // Close the PDF document
        pdfDocument.close();
    }
 
    public static void main(String[] args) {
        try {
            convertXpsToPdf("input.xps", "output.pdf");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Explanation:

• The code first creates a new PDF document using Apache PDFBox.
• It then uses JavaFX's WebView to load the XPS file.
• After waiting for the page to load, it captures the WebView as an image.
• The image is then added to the PDF page and the PDF document is saved.

Conclusion#

Converting XPS to PDF in Java is a useful task in many real - world scenarios. By understanding the core concepts, being aware of common pitfalls, and following best practices, you can achieve high - quality conversions. Third - party libraries like Apache PDFBox provide powerful APIs to simplify the conversion process.

FAQ#

Q1: Can I convert multiple XPS files to PDF in one go?#

Yes, you can write a loop in Java to iterate over multiple XPS files and call the conversion method for each file.

Q2: Are there any free alternatives to Apache PDFBox?#

Yes, iText is another popular open - source library for working with PDF files in Java.

Q3: What if the XPS file contains password protection?#

You need to handle the password authentication before loading the XPS file. Some libraries may provide methods to handle password - protected files.

References#

• Apache PDFBox Documentation: https://pdfbox.apache.org/
• JavaFX Documentation: https://openjfx.io/
• XPS Specification: https://docs.microsoft.com/en - us/previous - versions/windows/desktop/dd316980(v = vs.85)