Spring Boot integrates itext to realize the function of generating PDF from html

4 min readMar 28, 2024

1.itext introduction

iText is a project of the famous open source site sourceforge and is a java class library used to generate PDF documents. iText can not only generate PDF or rtf documents, but also convert XML and Html files into PDF files.

Features of iText

Interactive − iText provides you with classes (APIs) to generate interactive PDF documents. Using these you can create maps and books.
Adding bookmarks, page numbers, etc − Using iText, you can add bookmarks, page numbers, and watermarks.
Split & Merge − Using iText, you can split an existing PDF into multiple PDFs and add/join additional pages to it.
Fill Forms − Using iText you can fill out interactive forms in PDF documents。
Save as Image − Using iText, you can save a PDF as an image file, such as PNG or JPEG.
Canvas − iText library provides you with a Canvas class that you can use to draw various geometric shapes on PDF documents, such as circles, lines, etc.
Create PDFs − Using iText, you can create new PDF files from a Java program. You can also include images and fonts.

2.Code Project

Experimental goal: Generate thymeleaf views into PDF

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>itextpdf</artifactId>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>html2pdf</artifactId>
            <version>3.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>kernel</artifactId>
            <version>7.1.12</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
</project>

application.yaml

server:
  port: 8088
spring:
  thymeleaf:
    cache: false

DemoApplication

package com.et.itextpdf;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@ServletComponentScan
@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

controller

converterProperties.setBaseUri is important. Otherwise, static resources like /main.css will not be found

package com.et.itextpdf.controller;
import com.et.itextpdf.pojo.Order;
import com.et.itextpdf.util.OrderHelper;
import com.itextpdf.html2pdf.ConverterProperties;
import com.itextpdf.html2pdf.HtmlConverter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.WebContext;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
@Controller
@RequestMapping("/orders")
public class PDFController {

    @Autowired
    ServletContext servletContext;
    private final TemplateEngine templateEngine;
    public PDFController(TemplateEngine templateEngine) {
        this.templateEngine = templateEngine;
    }
    @RequestMapping(path = "/")
    public String getOrderPage(Model model) {
        Order order = OrderHelper.getOrder();
        model.addAttribute("orderEntry", order);
        return "order";
    }
    @RequestMapping(path = "/pdf")
    public ResponseEntity<?> getPDF(HttpServletRequest request, HttpServletResponse response) throws IOException {
        /* Do Business Logic*/
        Order order = OrderHelper.getOrder();
        /* Create HTML using Thymeleaf template Engine */
        WebContext context = new WebContext(request, response, servletContext);
        context.setVariable("orderEntry", order);
        String orderHtml = templateEngine.process("order", context);
        /* Setup Source and target I/O streams */
        ByteArrayOutputStream target = new ByteArrayOutputStream();
        ConverterProperties converterProperties = new ConverterProperties();
        converterProperties.setBaseUri("http://localhost:8088");
        /* Call convert method */
        HtmlConverter.convertToPdf(orderHtml, target, converterProperties);
        /* extract output as bytes */
        byte[] bytes = target.toByteArray();

        /* Send the response as downloadable PDF */
        return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=order.pdf")
                .contentType(MediaType.APPLICATION_PDF)
                .body(bytes);
    }
}

view

Spring MVC comes with a template engine that can serve dynamic HTML content. We can easily convert these responses to PDF format using the following method. In this example, I imported spring-boot-starter-web and spring-boot-starter-thymeleaf to provide MVC and thymeleaf support for my spring boot project. You can use the template engine of your choice. Take a look at the contents of the thymeleaf template below. Mainly displays order details. In addition, some virtual order content is generated through the auxiliary methods of OrderHelper.

<!doctype html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <meta content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
          name="viewport">
    <meta content="ie=edge" http-equiv="X-UA-Compatible">
    <title>Spring Boot - Thymeleaf</title>
    <link th:href="@{/main.css}" rel="stylesheet"/>
</head>
<body class="flex items-center justify-center h-screen">
<div class="rounded-lg border shadow-lg p-10 w-3/5">
    <div class="flex flex-row justify-between pb-4">
        <div>
            <h2 class="text-xl font-bold">Order #<span class="text-green-600" th:text="${orderEntry.orderId}"></span>
            </h2>
        </div>
        <div>
            <div class="text-xl font-bold" th:text="${orderEntry.date}"></div>
        </div>
    </div>
    <div class="flex flex-col pb-8">
        <div class="pb-2">
            <h2 class="text-xl font-bold">Delivery Address</h2>
        </div>
        <div th:text="${orderEntry.account.address.street}"></div>
        <div th:text="${orderEntry.account.address.city}"></div>
        <div th:text="${orderEntry.account.address.state}"></div>
        <div th:text="${orderEntry.account.address.zipCode}"></div>
  </div>
    <table class="table-fixed w-full text-right border rounded">
        <thead class="bg-gray-100">
        <tr>
            <th class="text-left pl-4">Product</th>
            <th>Qty</th>
            <th>Price</th>
            <th class="pr-4">Total</th>
        </tr>
        </thead>
        <tbody>
        <tr th:each="item : ${orderEntry.items}">
            <td class="pl-4 text-left" th:text="${item.name}"></td>
            <td th:text="${item.quantity}"></td>
            <td th:text="${item.price}"></td>
            <td class="pr-4" th:text="${item.price * item.quantity}"></td>
        </tr>
        </tbody>
    </table>
    <div class="flex flex-row-reverse p-5">
        <h2 class="font-medium  bg-gray-200 p-2 rounded">
            Grand Total: <span class="text-green-600" th:text="${orderEntry.payment.amount}"></span>
        </h2>
    </div>
    <h2 class="text-xl font-bold">Payment Details</h2>
    <table class="table-fixed text-left w-2/6 border">
        <tr>
            <th class="text-green-600">Card Number</th>
            <td th:text="${orderEntry.payment.cardNumber}"></td>
        </tr>
        <tr>
            <th class="text-green-600">CVV</th>
            <td th:text="${orderEntry.payment.cvv}"></td>
        </tr>
        <tr>
            <th class="text-green-600">Expires (MM/YYYY)</th>
            <td th:text="${orderEntry.payment.month +'/'+ orderEntry.payment.year}"></td>
        </tr>
    </table>
</div>
</body>
</html>

POJO

package com.et.itextpdf.pojo;
import lombok.Data;
@Data
public class Account {
    private String name;
    private String phoneNumber;
    private String email;
    private Address address;

}

package com.et.itextpdf.pojo;
import lombok.Data;
@Data
public class Address {
    private String street;
    private String city;
    private String state;
    private String zipCode;
}

package com.et.itextpdf.pojo;
import lombok.Data;
import java.math.BigDecimal;
@Data
public class Item {
    private String sku;
    private String name;
    private Integer quantity;
    private BigDecimal price;
}

package com.et.itextpdf.pojo;
import lombok.Data;
import java.util.List;
@Data
public class Order {
    private Integer orderId;
    private String date;
    private Account account;
    private Payment payment;
    private List<Item> items;
}

package com.et.itextpdf.pojo;
import lombok.Data;
import java.math.BigDecimal;
@Data
public class Payment {
    private BigDecimal amount;
    private String cardNumber;
    private String cvv;
    private String month;
    private String year;
}

The above are just some key codes. For all codes, please see the code repository below.