dependencies {
    implementation 'com.itextpdf:html2pdf:4.0.0'
}

import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;
import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;

public class TemplateProcessor {
    public static String processTemplate(Map<String, Object> data, String templateName) {
        ClassLoaderTemplateResolver resolver = new ClassLoaderTemplateResolver();
        resolver.setSuffix(".html");
        resolver.setTemplateMode("HTML");
        TemplateEngine templateEngine = new TemplateEngine();
        templateEngine.setTemplateResolver(resolver);
        Context context = new Context();
        context.setVariables(data);
        return templateEngine.process(templateName, context);
    }
}

import com.itextpdf.html2pdf.HtmlConverter;
import java.io.ByteArrayInputStream;
import java.io.FileOutputStream;
import java.util.*;

public class HtmlToPdfExample {
    public static void main(String[] args) throws Exception {
        Map<String, Object> data = new HashMap<>();
        List<Map<String, Object>> items = new ArrayList<>();
        items.add(createItem("Widget A", 10, 15.00));
        items.add(createItem("Widget B", 5, 20.00));
        data.put("items", items);
        data.put("total", "$250.00");
        String htmlContent = TemplateProcessor.processTemplate(data, "invoice");
        HtmlConverter.convertToPdf(new ByteArrayInputStream(htmlContent.getBytes()), new FileOutputStream("generated_invoice.pdf"));
    }

private static Map<String, Object> createItem(String description, int quantity, double unitPrice) {
        Map<String, Object> item = new HashMap<>();
        item.put("description", description);
        item.put("quantity", quantity);
        item.put("unitPrice", String.format("$%.2f", unitPrice));
        item.put("amount", String.format("$%.2f", quantity * unitPrice));
        return item;
    }
}

import com.itextpdf.html2pdf.ConverterProperties;
import com.itextpdf.io.font.FontConstants;
import com.itextpdf.layout.font.FontProvider;

ConverterProperties properties = new ConverterProperties();
FontProvider fontProvider = new FontProvider();
fontProvider.addStandardPdfFonts();
fontProvider.addDirectory("path/to/fonts/");
properties.setFontProvider(fontProvider);
HtmlConverter.convertToPdf(
    new ByteArrayInputStream(htmlContent.getBytes()), 
    new FileOutputStream("generated_invoice.pdf"), 
    properties
);

import com.itextpdf.kernel.pdf.*;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Paragraph;

public class WatermarkAdder {
    public static void addWatermark(String src, String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
        Document document = new Document(pdfDoc);
        int n = pdfDoc.getNumberOfPages();
        for (int i = 1; i <= n; i++) {
            PdfPage page = pdfDoc.getPage(i);
            PdfCanvas canvas = new PdfCanvas(page);
            canvas.saveState();
            canvas.beginText();
            canvas.setFontAndSize(PdfFontFactory.createFont(FontConstants.HELVETICA), 60);
            canvas.setColor(ColorConstants.LIGHT_GRAY, true);
            canvas.showTextAligned(new Paragraph("CONFIDENTIAL"), 298, 421, pdfDoc.getPageNumber(page), TextAlignment.CENTER, VerticalAlignment.MIDDLE, 45);
            canvas.endText();
            canvas.restoreState();
        }
        document.close();
    }
}

import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;

public class PdfForgeExample {
    public static void main(String[] args) {
        try {
            URL url = new URL("https://api.pdfnoodle.com/v1/html-to-pdf/sync");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Authorization", "Bearer your-api-key");
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setDoOutput(true);

            String jsonInputString = " { \"html\": \"your-html\" }";

            try(OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream())) {
                writer.write(jsonInputString);
                writer.flush();
            }

            int responseCode = conn.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                // Read the response and process the PDF
            } else {
                // Handle errors
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}