How to Generate PDFs with Thymeleaf and iText in Spring Boot – A Step-by-Step Guide

Adding Maven Dependencies

<!--PDF转化工具-->
<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.4.2</version>
</dependency>
<dependency>
    <groupId>org.xhtmlrenderer</groupId>
    <artifactId>core-renderer</artifactId>
    <version>R8</version>
</dependency>

PDF Utility Class

import com.itextpdf.text.pdf.BaseFont;
import com.lowagie.text.DocumentException;
import org.springframework.stereotype.Component;
import org.xhtmlrenderer.pdf.ITextFontResolver;
import org.xhtmlrenderer.pdf.ITextRenderer;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Export PDF file conversion tool
 */
public class PDFUtil {
    /**
     * Generate PDF file
     * @param out output stream
     * @param html HTML string
     * @throws IOException IO exception
     * @throws DocumentException Document exception
     */
    public static void createPDF(OutputStream out, String html) throws IOException, DocumentException {
        ITextRenderer renderer = new ITextRenderer();
        renderer.setDocumentFromString(html);
        // Resolve Chinese font support
        ITextFontResolver fontResolver = renderer.getFontResolver();
        fontResolver.addFont("pdf/font/fangsong.ttf", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
        fontResolver.addFont("pdf/font/PingFangSC.ttf", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
        renderer.layout();
        renderer.createPDF(out);
    }
}

Font files must be downloaded and placed under the resources directory; adjust the paths in the code accordingly.

Demo Output

Common Issues and Fixes

1. Maven packaging alters HTML placeholders

Cause: Maven filtering processes ${} placeholders, which conflicts with Thymeleaf syntax.

Solution: Configure the section in pom.xml to disable filtering for HTML files.

<build>
    ...
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
            <excludes>
                <exclude>**/*.html</exclude>
            </excludes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>false</filtering>
            <includes>
                <include>**/*.html</include>
            </includes>
        </resource>
    </resources>
</build>

2. Docker build fails due to missing font classes

Use the java:8 base image instead of openjdk:8-jre-alpine to ensure required font handling classes are available.