Thymeleaf (Java)

This guide explains how to generate an HTML string using Java's Thymeleaf template engine and convert it to PDF by sending it to pdfg's API.

Technical Overview

Create a Thymeleaf template
Pass data to the template to generate an HTML string
Send the generated HTML string to pdfg's API to convert it to PDF

Sample

Defining the Template

<!-- templates/invoice.html -->
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
  <head></head>
  <body>
    <div class="invoice">
      <h1>Invoice</h1>
      <table>
        <thead>
          <tr>
            <th>Item</th>
            <th>Amount</th>
          </tr>
        </thead>
        <tbody>
          <tr th:each="item : ${items}">
            <td th:text="${item.name}"></td>
            <td th:text="${item.price} + ' USD'"></td>
          </tr>
        </tbody>
      </table>
      <p class="total" th:text="'Total: ' + ${total} + ' USD'"></p>
    </div>
  </body>
</html>

Using the Template and Generating PDF

// GeneratePdf.java
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;
import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;
import java.util.Map;

public class GeneratePdf {
public static void main(String[] args) throws Exception {
// Configure Thymeleaf
TemplateEngine templateEngine = new TemplateEngine();
ClassLoaderTemplateResolver resolver = new ClassLoaderTemplateResolver();
resolver.setPrefix("/templates/");
resolver.setSuffix(".html");
templateEngine.setTemplateResolver(resolver);

        // Prepare data
        List<Map<String, Object>> items = List.of(
            Map.of("name", "Product A", "price", 1000),
            Map.of("name", "Product B", "price", 2000)
        );
        int total = 3000;

        // Set context
        Context context = new Context();
        context.setVariable("items", items);
        context.setVariable("total", total);

        // Generate HTML string
        String html = templateEngine.process("invoice", context);

        // Create request body
        String requestBody = String.format("""
            {
                "html": "%s",
                "pdfOptions": {
                    "format": "A4"
                }
            }
            """, html.replace("\"", "\\\""));

        // Request to pdfg's API
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.pdfg.net/v1"))
            .header("Content-Type", "application/json")
            .header("Authorization", "Bearer YOUR_API_KEY")
            .POST(HttpRequest.BodyPublishers.ofString(requestBody))
            .build();

        HttpResponse<byte[]> response = client.send(request,
            HttpResponse.BodyHandlers.ofByteArray());

        // Save PDF
        if (response.statusCode() == 200) {
            Files.write(Path.of("invoice.pdf"), response.body());
        }
    }
}

Blade (PHP)Go